Jyotika's Tropical Storms Blog: July 2008

Thursday, July 24, 2008

Tropical Storm Dolly: July 24 Update A

Dolly is pretty weak now, with winds of 45 mph (TS: 39-73mph) and
weakening steadily. Her center of circulation just crossed into Mexico
and is at about 27.7N, 100W heading W-NW at 9mph. She still has some
rain, mostly in the northeast quadrant - over Texas, but that is also
diminishing. Not much more to say about her. So this is my last entry on
this system - I'm Done with Dolly. :)

For you crazy kids who decided it was a good idea to go to places like
Puerto Rico and the Keys during hurricane season, there's an area of
circulation out in the Atlantic, centered around 17N, 36W. Although the
circulation is good, there is not much water vapor in it at the moment.
It has been traveling over sea surface temperatures of ~25 deg C, which
is too cold for much to happen, but it is about to cross into a region
with 26 deg C temperatures. I'll keep an eye on it, but I did a rough
estimate of its forward motion and if anything does develop (which
doesn't look likely at the moment) I think you'll be back from those
respective places in time. So have fun. I'm not going to write about
this until there's something more substantial.

That's all for now folks. (woo-hoo... time for a nap before the
hurricane season *really* begins... ;) )
J.

Blogs archived at: http://www.jyotikastorms.blogspot.com/
------------------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and
the National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.
-------------------------------------------

Wednesday, July 23, 2008

Hurricane Dolly: July 23 Update B

Her eye is currently (~1pm EST) crossing South Padre Island, about 35
miles NE of Brownsville, TX. They have her listed as a weak category 2
storm with winds near 100 mph (cat 2: 96-110 mph). She looks weaker than
that to me, but as I said earlier, there is very little difference
between a really strong cat 1 and a very weak cat 2. She's moving NW at
7mph. The really strong convection has decreased quite a bit since this
morning and her eye is looking even more ragged, although there is still
some strong "stuff" (technical term :) ) in the system. Hurricane force
winds extend out 25 miles from the eye.

Hurricane Dolly: July 23 Update A

She'll make landfall within the next four hours. The eye is just
off-shore from Brownsville - at 8am this morning it was ~40 miles east.
She is now centered at 26N, 96.9W and was traveling NW at 8mph at the
8am advisory. Although the eye will make landfall in that part of Texas,
she's a big storm so there will be some rough weather with the outer
bands over most of the coastal (and some inland) areas of Texas and Mexico.

The eye is easily visible and winds at the 8am advisory this morning
were at 95 mph, making her a strong cat 1 (74-95mph), almost cat 2
(96-110mph). Central pressure is estimated to be 967mb. It does not look
like she has improved since then - there are fewer bands of really
strong convection and the eye is a little cloudier than before, so she
may remain a strong cat 1 storm at landfall. But the wind speed
difference between a cat 1 and 2 at this stage is so minuscule that it
really makes little difference. There is a lot of rain and stormy
weather in the bands.

From the observations, the closest location to Brownsville that we have
data from is also where the highest storm surge is at the moment: it is
~3 ft above normal at Port Isabel, which is near South Padre Island, and
about 22 miles NE of the center of Brownsville (isn't mapquest great?).
I had a quick look at a number of other stations in Texas, and they were
all showing less than that.

I'll send out a note when she's made landfall.
J.

Tuesday, July 22, 2008

TS Cristobal and Hurricane Dolly: July 22 Update B

TS Cristobal:
Currently at about 42.2N, 62.5W, he has weakened and has winds of 50 mph
(TS: 39-73 mph) so he's a fairly weak storm now with a central pressure
of 1005mb. He's zipping along in a NE direction at 28 mph. There was an
increase in rainfall activity during the day today, but that is dying
down again now and they system is slowly becoming extratropical
according to the NHS (I can't tell that part from the information I
have). I think this will be my last entry on our friend Cristobal. He
was a goodly little storm that did not create too much mayhem. :)

Hurricane Dolly:
A plane found hurricane force winds near 75 mph this afternoon (cat 1:
74-95 mph) so she is now a weak category 1 storm with a central pressure
of 986mb, located at 24.6N, 95.3W. There is no clearly defined eye yet,
but you can see where it should be. She's moving NW at 10 mph, and her
circulation at all levels in the troposphere has improved, suggesting
further strengthening before she makes landfall. Landfall will be
tomorrow, in the Brownsville, Texas area, right on the Texas-Mexico
border. She's a large storm so her outer bands extend all the way to the
southern Gulf states.

Water levels along some parts of the Texas coast are, at the moment,
about 1 foot above normal. You can look at this for yourself by going to
Tides Online - a NOAA/National Ocean Service:
http://tidesonline.nos.noaa.gov/geographic.html. Click on 'State Maps'
on the left panel, and then click on the state you are interested in and
then on the location of interest. Let me know if you have any questions
like umm... Where is Texas? Are they still part of the US? What are all
the other letters on the map? ;)

Actually, I've been to parts of Texas and it is a very nice state. I
have some good friends who live there. My web blog expert also lives in
Texas. And I still talk to them all from time to time. Really. I do.

Have a good evening everyone and if you are in coastal areas of Texas
(and actually Louisiana as well), be good.
J.

TS Cristobal and TS Dolly: July 22 Update A

TS Cristobal:
He's still hanging on, partly because he's over sea surface temperatures
of 26-27 deg C. He is in a higher wind shear environment now, but there
is not too much rainfall activity. Just some clouds and a lot of wind.
Winds are at 65 mph, so still a fairly strong tropical storm (39-73mph)
and his 'center' is located somewhere around 41N, 66W. Circulation is in
the lower troposphere (lowest section of our atmosphere) only. He is
heading NE at 25 mph and will soon be over cooler waters and in a high
wind shear. I'm not sure he will last for too long - and that is in
agreement with the NHC.

TS Dolly:
Her winds are near 70 mph, so she is still a TS but a strong one -
almost at hurricane strength. They say an eye is developing, but it
looks about as developed as the satellite images were showing yesterday,
however their data is from a plane that flew threw this morning and also
found a central pressure of 991mb. She's at 24N, 94.5W and is moving NW
at 12 mph. Water temperatures beneath her are 29 deg C, and the upper
~70 m has 26 degC or warmer. The forecast calls for a NW or WNW track
with some slowing down before she makes landfall tomorrow. I would agree
with that. I also agree with the track - landfall somewhere in the
Texas/Mexico area (although at the moment Mexico looks more likely to me
because the high pressure is still covering most of the northern Gulf
and Texas - but we'll see if the next set of information shows any
change in the pressure field). There is some strong convection, although
it has decreased a little in the last couple of hours. The areal extent
of this storm is pretty big - the outer bands are bringing clouds and
rain to Mississippi. Circulation has improved and is now over the entire
troposphere.

Gotta go... more later,
J.

TS Cristobal and TS Dolly: July 21 Update B

Quick evening update:

TS Cristobal:
He's steadily degraded this afternoon/evening and hardly has any rain
-just a mass of windy cloudy sort of weather. Like a lovely British summer
day ;) He is moving ENE at 16mph, and although his winds at the 11pm
advisory were still 60 mph (TS: 39-73 mph) I am not sure if he will
survive another day as a TS. I think they must have moved his official
center at some point during the day, because it is now within the area of
cloudiness. Unless something "interesting" happens, I expect I will be
stopping updates on him tomorrow.

TS Dolly:
She did not intensify much today as I thought she would. So it seems as
though the shallow warm waters took their toll because all other factors
seemed to be favorable. Of course, those who are paying attention know
that there is something else at play in the intensity forecasts that we
don't have a good understanding of. I will say that the NHC and models
called this correctly as not intensifying to a hurricane until tomorrow.
We'll see what happens then.

The intensity of her convection has steadily decreased during the day, but
the areal extent of her cloudiness has spread and now encompasses a large
area of the Gulf. Some of the outer clouds are already over land
(Texas/Mexico, and even other parts around the Gulf). So I will be very
interested to see if she does intensify tomorrow as forecast.

Her forecast track is pretty good - somewhere around the Texas/Mexico
border. At the moment, I would still say Mexico for landfall, but that's
just me (and a few models). She is moving west at 17 mph, as we expected,
although it looks like she's about to resume her W-NW motion. Max. winds
are 50 mph, central pressure 999mb and she's around 23.1N, 92.8W.
Circulation is still good in the lower to mid levels of the atmosphere.

Another lovely day in Paradise comes to a close.
Night night.
J.

Monday, July 21, 2008

TS Cristobal and TS Dolly: July 21 Update A

TS Dolly:
As a number of you noted, the center of Dolly was shifted northwards
this morning and now I feel much better about this system. :) I now
agree with the NHC that she is truly a tropical storm and is shaping up
very nicely (in a scientific sense). My concern with the center not
being correctly located yesterday is playing out today - with the more
northern location, she barely clipped the Yucatan Peninsula so she is a
lot stronger this morning than she would have been if she had followed
the track they had yesterday which would have taken her over land for a
longer period of time. This now sets her up to become a stronger storm.
There are hurricane and tropical storm watches along the Texas and
Mexico coastlines and the NHC expect her to become a cat 1 storm
tomorrow, with landfall on Weds. I would not be surprised if she becomes
a hurricane by the end of today given her little interaction with land,
warm waters and low wind shear environment.

Currently, she is at 22.1N, 89.5W and has winds of 50 mph, central
pressure of 1005mb (TS wind range: 39-73 mph). A plane went into the
system this morning and confirmed closed circulation, which is obvious
in any satellite image of her now. She is moving a little more westward
than yesterday, which is also something I was expecting given the
surrounding pressure fields. Her motion is W-NW at 18 mph. The exact
landfall location is still unknown, so keep an eye on the entire cone
not just the center.

From this point out, sea surface temperatures in her track are between
28-31 deg C - very warm. The warmer 26 deg C temperatures extend down to
about 75 m depth across most of the southern Gulf, but at the moment she
is also interacting with the very shallow and broad Campeche Banks just
north and west of the Yucutan Peninsula where warm waters only extend
down to about 25m. I keep mentioning the warm water and how deep it is
because as a storm passes over the surface it churns up water from
beneath the surface. As you can imagine, it makes a difference if the
water being churned up is cold or warm. I disagree with the NHC in
their assessment of the reservoir of warm water underneath:

"IN ABOUT 18-24 HOURS...DOLLY IS EXPECTED TO PASS OVER SSTS GREATER THAN
29 CELSIUS...AND A RELATIVE MAXIMUM IN OCEAN HEAT CONTENT...AN AREA WITH
A SOMEWHAT DEEPER RESERVOIR OF WARM WATER BENEATH THE SURFACE."

She passed over the relative maximum reservoir in upper ocean warm water
in the northern/eastern Caribbean - around Jamaica and slightly west, as
I mentioned in a much earlier entry. I'm not sure what information they
are basing this statement on.

Dolly is growing in areal extent and there is a lot of water vapor
around her - in fact she is impacting upper level winds over most of the
Gulf of Mexico. I will discuss her further this afternoon, after I get
the next set of pressure maps. For now though, I think she will continue
more westward than northward, and will continue to intensify.

TS Cristobal:
As with Dolly yesterday, I think the NHC have the center of circulation
in the wrong place. Although this storm does not have a good structure,
they have the center located at 36.6N, 72.6W. This is entirely north of
the area of convection. It almost looks to me as though the center is
about 1 degree south - at 35.6N, 72.6W. Maybe someone just entered the
wrong number? He is moving NE at 13mph, and is following a high pressure
system (remember, things move clockwise around a high pressure in the
northern hemisphere). Winds have picked up to 65 mph, making him a
strong Tropical Storm now. I think it was yesterday I said we could
expect some strengthening because he is moving away from land and is
still over warm waters of 27-28 deg C. At least an incorrect center in
this case will not affect anyone (unless you are out on a boat in the
Atlantic).

That's all for now - more later when I have the latest pressure
information in hand.
Toodles,
J.

TS Dolly: July 20 Update B - Special Note

O.k... I can't keep quiet anymore. There is something a bit dodgy about
this system. Either this should not be a named Tropical Storm (and not
because "Dolly" was the name of a cute and fluffy cloned sheep) or the NHC
have the center incorrectly idenitified and continue to do so.

The latest (11pm) advisory has the center at 19.6N, 85.6W ... which is
south of any convective activity. So either the center is completely
offset from the convection, in which case this system is so disorganized
it should not be a storm, or the center should be ~1 degree north of its
current official location and it will barely clip the Yucatan or may just
pass through the Strait - which will make a difference in it's future
track and intensity. The official center looked too far south to me all
day today relative to the convection (e.g. previous entry) and continues
to do so. If there is a center where the official one is, then I am not
convinced this is, or has been so far, a proper TS. For most of the
lifetime (to date) of this 'Blob' the circulation has not been the same as
the region of convection.

The NHC are hedging their bets already I think:

"DATA FROM A NOAA P3 AIRCRAFT INDICATE THAT DOLLY HAS NOT BECOME ANY
BETTER ORGANIZED THIS EVENING. INDEED...THE SYSTEM PROBABLY
DOESN'T HAVE A CLOSED SURFACE CENTER RIGHT NOW" ... "SINCE DOLLY COULD
REGENERATE A CENTER AT ANY TIME...NO GOOD WOULD BE SERVED BY
HANGING ON A TECHNICALITY."

and

"THE INTENSITY FORECAST ASSUMES THAT THERE WILL BE SOME DISRUPTION OF THE
SYSTEM OVER THE YUCATAN...WHICH COULD BE AVOIDED IF A CENTER REFORMS TO
THE NORTH WITHIN THE DEEP CONVECTION."

This suggests to me that they already know/suspect it is north of their
official location... and for now at least, it is not technically a TS.

Sure there is some strong convection - but there has been for days and
days with this system. That is not reason enough for naming a system.

My problem with mis-defining systems is that this then becomes a
'statistic', so instead of having 3 named storms, we now have 4. We saw
this last year as well. I'll get into the whole storms and 'active' season
and climate discussion some other time though.

We'll see what happens by the morning - where exactly it passes over the
Yucatan Peninsula will tell us more. Dodgy Dolly. Hmm...looks like the
alliterations are not over yet!

Now that's off my mind I can go to sleep. :)
J.

Sunday, July 20, 2008

TS Bertha, TS Cristobal and TS Dolly: July 20 Update A

I thought I'd take it easy today as there was not much going on....

TS Bertha:
She became extratropical this morning and is currently at about 55N, 32W,
heading NE at 36 mph directly towards Iceland. There's not much rain in
this system, just some clouds and blustery winds of ~70 mph... so it will
be just another normal day in Iceland ina day or two. The NHC's last
advisory on this was at 11am this morning, but to show they are working,
she's been replaced (see below). This is my last entry on Beautiful,
Bemusing, Big, Boundless Bertha. I can barely remember when she first
began! The End.

TS Cristobal:
He is currently about 35N, 76W and in a few hours will be moving away from
the US. His heading is NE at 8mph, and he has winds of about 45 mph (TS:
39-74 mph). His convection has been weak for most of the last 24 hours,
but it has picked up this afternoon - most of the strongest activity
remains off-shore though (off the NC coast). For the most part, I think it
was a windy day in the Carolinas - maybe a few thunderstorms here and
there, but nothing too major. He is over water temperatures of 29 deg C,
and as he moves away from the coast there is a chance for some
intensification.

TS Dolly:
Formally known as 'The Blob', this storm went straight past the Tropical
Depression designation to a named Tropical Storm. We know she's had a lot
of convection, heavy and large thunderstorms etc since the beginning. But
this morning a plane found some closed circulation in the system and a
buoy reported sustained tropical force winds over a period of 4 hours. Her
circulation is not quite as strong as it was when she was named, but the
convection is still really severe, so she will remain a TS. Her winds are
around 45 mph, but I think that may increase a bit before landfall in the
Yucutan overnight. She is over very warm waters of 29-32 deg C, the warm
waters are deep, and she is in a low wind shear environment. Her
intensification will depend on how quickly she gets to the Yucutan
Peninsula and how long she stays over land - which will inhibit
intensification. There are strong thunderstorms over Cuba and the Caymans
at the moment.

The forecast track takes her over the northern Yucutan, then out into the
Gulf and towards the Mexico/Texas border on wednesday afternoon. The
waters are also warm over the Gulf so she may intensify further and the
models all currently predict her becoming a hurricane. She's currently
somewhere around 19N, 85W, but the center is difficult to see because she
is not very well organized. It almost looks like the center is a little
north of the official one (closer to 20N, 85W), but they got their
information by flying through the system so I will go with that. The
pressure maps I am looking at show that there is a high pressure that is
currently siting over the Gulf, extending down into Mexico. Unless that
changes tomorrow, there's a chance that she will clip the Yucutan
peninsula and then take a more W-NW path than the NW one currently
forecast, taking her into Mexico. In which case, she may not have time to
intensify to hurricane strength after crossing the Yucutan.

I'm sure there will be more fun and games tomorrow...
Ciao,
J.

Saturday, July 19, 2008

TS Bertha, TS Cristobal and The Blob: July 19 Update B

Quick update...

TS Bertha:
She's slowly degrading and no longer has an eye. Located at 45.7N, 41.8W,
she is racing NE at 24 mph. Winds are 70 mph, so she is still a strong TS
(winds: 39-74mph). Given the colder waters it is unlikely she will get
stronger from this point out.

TS Cristobal:
Formally TD 3, he was named this morning when he had some better
convection. Although there is still some good circulation with this
system, the convection has been decreasing all day and he looks quite
ragged at the moment - he barely looks like a TS actually. He is centered
(according to the NHC) at 33.4N, 77.5W and is moving NE at 6mph. Winds are
45mph, so he is a fairly weak TS. The track takes him close to Cape
Hatteras in less than 24 hours. I think they will send in another plane in
the morning to see what's going on.

The Blob:
There is still some circulation in the lower atmosphere, but it is not
very well organized. It is now just southwest of Jamaica. The convection
is still strong in parts, although that has decreased this evening as
well. The convection is around 80W now, and spread from 15N-23N, so it
extends into Cuba. The high pressure has not eroded northward today, so
this may pass through the Yucutan Channel or clip the Yucatan peninsula,
but at the moment it will stay south of the US. This blob is moving W-NW
at ~15mph. It's not yet a Tropical Depression.

More tomorrow.
J.

Hurricane Bertha, Tropical Depression 3 and The Blob: July 19 Update A

Tropical Depression 3, formerly known as 'The Blobette':

Last night the NHC upgraded this system to a TD. It has winds of 35 mph, a
central pressure of 1007 mb and is moving NE at 7mph. They say it's
current center of circulation is 32.6N, 78.5W, but it is not very well
developed so it is difficult for me to confirm that. This is a little east
of their previous assessment of the center, which is why the track has
been shifted east and slightly away from the coast. In my opinion,
yesterday it was closer to land which is why it was not developing much,
but it has actually shifted slightly away from land (eastward) - enough so
that now it is completely over the Gulf Stream and over waters of 28-30
deg C, and consequently the convection and circulation have improved and
it has grown in areal extent, with clouds extending south into the
northern Bahamas. There is some circulation (vorticity) in the lower and
mid levels of the troposphere.

A number of factors will now allow this storm to intensify:
1. it is not as close to land (although it is still quite close)
2. it is over waters of 28-30 deg C
3. warm waters of 26 deg C can be found at depths of around 75m
4. there is very little wind shear - now and over the next couple of days

It looks like it will be a Tropical Storm (wind range: 39-73mph) by the
end of today - this is in agreement with the NHC forecast - and the
unknown part is will it eventually become a hurricane during its life. A
plane is on its way into the storm to investigate. So far, most of the
really heavy convection has remained off-shore. The next named storm is
Cristobal, a guys name. So our "blobette" will become a he-storm :)

The Blob:
This is still a really intense mass of convective activity over the
northern Caribbean. The convection now covers Jamaica and Cuba - lots of
rain, thunder, lightning. Clouds from this have extended northwards to
cover the southern Bahamas as well - but not as much rain yet. There is
still some low level circulation, which interestingly is south of Jamaica
although most of the convection is in a N-S direction north of the
circulation. According to the NHC, it is moving W-NW at 15 mph. The
convection is over the warmest waters of the Caribbean ranging from 28-32
deg C. The best thing about this Blob is that it is helping to transfer
some heat from the ocean to the atmosphere and over land through rainfall,
without actually being a full-fledged tropical storm with associated
strong winds. It is still worth keeping an eye on it. The computer models
have shifted their track slightly northward, which is what I was
expecting. We still need to keep an eye on this in case it develops and
there is a chance it could enter the Gulf.

For those of you who read this and pay attention (and apparently some of
you do, although I'm not sure why), you may have noticed I mentioned the
Bahamas a couple of times already... well in a few hours, the clouds from
TD 3 and from The Blob will meet. These are just clouds and water vapor
from the two systems, so I don't think there will be very stormy weather
(unlike the Hollywood version of something like this), but it's
interesting to see this rendezvous over the Bahamas.

Hurricane Bertha:
If you ask most men, they will tell you that women are a mystery. That
also applies to Bertha. She is maintaining herself as a hurricane, albeit
a weak one with winds of 75 mph (cat 1: 74-95mph) but she looks good :)
She's now a hurricane not because of the ocean environment, where
temperatures are cold for a storm at 23-25 deg C, but because of the
atmospheric conditions. I don't think anyone in the hurricane science
community really knows why she is still so strong - again she demonstrates
to us that we still have a lot to learn about tropical storms and what
makes them tick. She is also showing us that a tropical storm is truly a
mix of ocean and atmosphere. I think her final alliteration will end up
being 'Bemusing Bertha'.

She's at about 43.1N, 45.4W and heading NE at a fast 25 mph. There is not
much in the way of heavy convection, but there are a lot of clouds
(without rain) which give her a beautiful image on satellite pictures.

Friday, July 18, 2008

Hurricane Bertha, the Blob and Blobette: July 18 Update B

Have you ever had one of those nightmares that just keeps on going and
going and going...? I'm just asking for no particular reason. You know.
Nothing to do with Bertha at all. Certainly nothing at all whatsoever to
do with her becoming a hurricane AGAIN.

Hurricane Bertha:
Yes, she intensified a bit (just a bit though) since the last message. I
know, I said it was unlikely she would intensify too much because she
was passing over colder waters. Silly me. A part of her (to the south)
is still interacting with warmer waters of 26-27 deg C. This morning she
had winds of 65 mph and now her winds are near 75 mph (cat 1 hurricane
range: 74-95 mph), central pressure 989 mb. So she is barely a
hurricane, and the only reason I agree with her upgrade is because she
has a big, somewhat cloudy, eye and looks like a hurricane. There is not
a lot of strong convection in this system and she's been in a low wind
shear environment. It looks like she's heading into higher wind shear,
which combined with the cooler temperatures should bring her back to TS.
However, she is now at 37.6N, 50.6W, moving NE (or NNE) at 22mph. Once
she's completely over cold waters she will become an extratropical
system as opposed to a tropical system, so she may still be quite windy
for a few more days.

For those who asked, the research vessel that's out there in the
Atlantic is 168 ft in length, 33 ft wide. Not too bad. Not too great
either. Well, at least they had an adventure ("always look on the bright
side of life, de-du, de-du, de-du de-du de-du" - Monty Python :) ).

The Blob:
The hurricane plane went to investigate this mass of clouds in the
Caribbean this afternoon and came back with reports of no closed
circulation. Now that I have all my usual data back, I can see that
there is some circulation but it is confined to the lower levels of the
atmosphere. This system still has the most convective activity - still
really severe thunderstorms - centered somewhere around 16N, 70-72W.
That mass is definitely heading in a NW direction - I still think it
will be north of the computer model tracks. Water temps are 27-29 deg C.

The Blobette:
This mass of clouds is still hanging mostly off the GA/SC/NC coast. The
convection has decreased a bit this afternoon. It still doesn't look
like too much rain is going to fall on GA and the Carolinas - most will
stay off-shore. It also has low-level circulation, centered somewhere
around 31N 80W, but nothing in the middle or higher levels of the
troposphere (which is the lowest level of our Atmosphere and extends
about 15-16km above the earth's surface in the tropics). Water
temperatures here are about 28-30 deg C.

---
I *just* got an email from the ship: "it's died right off in the last
few hours and is beautiful now. and yes we have the right tea." Ummm...
just to explain that last comment... being British and knowing they had
a rough few days, I suggested they should "have a cup of tea". What else
would I suggest? Thank goodness they have the right sort on board!
(P.G. Tips - there's no other ... hey, I should be get money from the
company for advertising I think. Or at least a few boxes of P.G. Tips tea.).

On that note I think I'll sign off. Have a good evening. Enjoy a cup of
tea ;)
I'll be back tomorrow.
Ciao,
J.

TS Bertha, the Blob and Blobette: July 18 Update A

Aaaghhh... the internet connection to one of the data sites is down....
aaaghhh... I NEED that data (cookie monster-esque person comes out of
her shell).
Deep breath. O.k., I'm back.

So, despite not having a full suite of information at my fingertips, I
am still going to send out a report now, and most definitely one or more
later today because everyone should keep an eye on the Blob and Blobette
I've been talking about for the past couple of days. But first...

... TS Bertha:
She's currently at 36.5N, 52W and speeding along at 18mph in a NE
direction and away from land. She intensified a little bit, which is not
surprising given that she was passing over warmer waters so he current
winds are at 65mph (TS range: 39-73mph). But it's unlikely she will
intensify much more because she's now passing over cooler sea surface
temps of 25-26 deg C. Generally, if all other things were favorable,
water temperatures of 26.5 deg C are needed to really keep a system
going. Consequently the convective activity is slowly decreasing and is
fairly weak at this point. She still has good circulation.

The research cruise are currently experiencing 'nice calm seas' of 8-10
ft... compared to the 'slightly choppy' 16-20ft seas they had yesterday
(by the way guys, how big is your boat??). They changed their science
plan a bit to take advantage of Big Bustling Bertha and have gone
looking for interesting upper water column impacts. I suppose they may
as well get something out of this, other than a weight loss program I mean.

The Blobette:
This is currently centered just off the GA coast. Circulation has
improved and looks to be somewhere around 31.5N, 80.7W, convection has
improved - but only over the eastern side where it's interacting with
the Gulf Stream and water temperatures of 28-30 deg C. The proximity to
land will inhibit too much growth, but the path it looks like it will
take at the moment is still along the east coast - GA, SC and NC,
basically right along the axes of the Gulf Stream. Those who've been
reading this for a couple of days will not be surprised by any of this.
I am not sure if it will create too many storms overland - most of the
convection is offshore and has been for the past day. The NHC issued a
special tropical disturbance statement on this system this morning and
will send in a plane tomorrow to investigate if necessary. It's not yet
officially a TD.

The Blob:
The mass of cloudiness and really strong convection that was skirting
the northern edge of S. America has moved a little more northwards -
because as I said yesterday, the high pressure that was keeping it to
the south is eroding northwards. It is difficult to find the center of
circulation, and without my full set of tools I can't say much about
that yet. The main area of convection is now around 15N, 70W. There are
some very strong thunderstorms in this area. The water temperatures
beneath are currently 27-28 deg C, but the warm waters in the Caribbean
are deep under the surface (26 deg C down to around 100m). Although the
computer model tracks are all keeping this to the south of Jamaica and
into the Yucatan (which I would have agreed with yesterday), given the
pressure fields I see today, if this develops into something, I think it
may actually pass north of Jamaica and interact with Cuba. The waters in
that entire northern Caribbean region are the warmest anywhere from the
eastern Atlantic to the Gulf, so this going to be an interesting 'Blob'
to watch. At it's current speed, it should pass the Jamaica region
around Sunday - but if you are heading there on Monday your flight may
be delayed... Again, a special tropical disturbance statement was issued
by the NHC at 11.25am, and they are sending in a plane to investigate
this afternoon. It is not yet officially a TD either.

More later ... when I'll have more data hopefully... need more data...
need more data... and a working, reliable crystal ball wouldn't hurt
either... :)
J.

Thursday, July 17, 2008

TS Bertha and the Blobs and Blobettes: July 17 Update B

TS Bertha:
She's still a good looking tropical storm in terms of wind (60mph) and
circulation, but the heavy rains are in the northeast quadrant which is
what I expected to see given that the eastern side is over warmer sea
surface temperatures of over 28 deg C. She is now at about 34 N, 57.2W
and is heading eastward at a faster 12mph. Tomorrow she will turn
towards the NE and away from this side of the Pond. One of these days
there won't be a TS Bertha - the end is nigh (...in a few days). I
promise.

For those who are following the research cruise, I finally heard again
from them earlier today (after silence yesterday): "We're getting some
pretty big swells at the moment and some people are looking quite
'ordinary'. " I asked for a clarification on 'ordinary'... I'm not 100%
convinced it's the "nicest" research cruise people have been on.

The Blobette:
This was the low that was over Florida yesterday. As I said yesterday,
the time to really start watching this was when it crossed to the
eastern side of the Florida peninsula and was over the Gulf Stream.
Well, it's there now. The circulation has improved in the lower
atmosphere and although there has not been too much rainfall with this
yet, the convection has increased steadily during the day. It is
currently about 75 miles east of Jacksonville, centered somewhere around
31N, 81W. It looks like it will head in a N-NE direction for now -
pretty much along the axis of the Gulf Stream. It is interacting with
land, which will prevent it from developing too much, but it may bring
some cloudy weather and a spot of lovely rain to Georgia and the
Carolinas. The rain over Florida today is connected to this as well. It
is not yet labeled a Tropical Depression though - so very light winds.

The Blob:
This is the bunch of clouds and really heavy rainfall that's moving
along the northern coast of South America. No change in the lower level
circulation in the atmosphere, and still no circulation aloft. It's
somewhere around 13N, 67W. It's heading westward at about 20-25 mph. The
only change really is that the high pressure that was keeping it to the
south is slowly eroding northwards, so it may head a little north
towards the Yucatan instead of the Nicaragua/Honduras portions of
Central America. That's still days away.

That's all for today folks.
J.

TS Bertha and assorted Blobs and Blobettes: July 17 Update A

TS Bertha:
She's behaving as predicted - can you believe it? Our rebellious little
storm is growing up. Aww. Or perhaps it could be that the track was
easier to forecast in the last couple of days? Hmm.... She's at 34.2N,
58.4W and has done her little SE wiggle and is now moving E-SE at 9mph,
which will shortly become Eastward and then NE as she continues to move
clockwise around the high (and counterclockwise around a Low to her
north). She's still a decent sized system with good circulation and
winds of 60mph (TS: 39-73mph) and central pressure of 997mb. Part of the
reason for her strength is that eastern side is still over warm water -
she's cooled the waters she passed over to her west. So for now she's
over water temperatures of 26-27 deg C, but will eventually clip
temperatures of 28-29 deg C which will keep her convective activity
going - at least on the eastern side of the system.

The NHC has put out a note to say if she survives as a tropical storm
into the weekend, she will be amongst the top 10 longest-lived storms
for which they have an accurate history. This doesn't mean much other
than an interesting little factoid. Bertha's got a lot of interesting
little factoids that I've already mentioned, such as becoming a
hurricane on July 7 this year, the same date that a previous Bertha in
1996 became a hurricane.

The Blob:
This is the mass of convection that was hanging out over the southern
windward islands yesterday - it's moved into the southern Caribbean. It
still has good circulation in the lower levels of the atmosphere and
there is some strong convective activity, but it is skimming the
northern end of the S. America landmass. At the moment there is a high
pressure system that covers the northern Caribbean, so this system will
continue moving pretty much in a westward direction (clockwise around
that high) and not come too far north. As you know, those fields may
change so I'll be keeping an eye on it. It's currently somewhere in the
12.3-13N, 65W area.

The Blobette:
This was the mass of convection that was loitering (suspiciously :) )
over Florida yesterday. It started in the Gulf of Mexico, but the actual
center of circulation was over central Florida. Well, there is still
decent circulation in the lower levels of the atmosphere, centered along
the NE Florida coast (and heading northeastward), but there is not too
much convection associated with this system at the moment - the rain
fell out over Florida yesterday. It is picking up some stuff from the
Gulf Stream but nothing major, and it still is very much interacting
with land. I'll keep an eye on this too.

The "other Blob":
This is also marked on the NHC site as an area of potential development
but it is close to central America so it may not amount to much on this
side of that land-mass. However if it moves quickly, it may be yet
another storm in the Pacific (they are on their 6th named storm so far).
It has some lovely convection - big thunderstorms - and low-level
atmospheric circulation.

That's about all for now. For those who have asked, I would not worry
about any of the above. I am not sure I like the new NHC front page
which marks these areas in 'danger' colours before they even become a
tropical depression. The good thing about all of this is that the
greater the convective activity (sans organization) we see, the more
heat is being transferred from the tropical ocean to the atmosphere and
then over land or northwards - and really, the purpose of Tropical
Storms are to move heat from the tropics to the extra-tropics. A
necessary element for our climate.

Toodles for now,
J.

Wednesday, July 16, 2008

TS Bertha, The Blob, and The Blobette: July 16 Update A

Well, things are not looking better all over the place today. I'm going
to keep this one short and send out a longer note later in the day.

TS Bertha:
She's located at 36.6N, 60.7W and has slowed down to 3mph, heading in a
sort of E-SE direction. The wind shear is kicking in as you can tell if
you look at her satellite images which are elongated. I know that this
has been the longest lasting tropical storm in July since 1916. I
haven't been watching the media, so I don't know what spin they may or
may not be putting on this statement. But it really doesn't mean too
much other than her surrounding environmental conditions were right for
her to develop and stay strong - not much wind shear for example. The
water temperatures are about average for this time of year, not
unusually warm. Water temperatures on her west side are about 25 deg C
and on her east about 27 deg C. The cooler west side waters are because
she has been hovering in that vicinity for a few days now.

The research cruise is still out there - somewhere around 31N, 63-64W.
I'm sure they are all having a wonderful time, enjoying the light
breeze... :)

The Blob:
This is at about 12.5N, 56.5 W and is the one that didn't have much
circulation over the past few days but I said I'd keep an eye on it ...
well it looks like there's some circulation in the area of convection in
the lower levels of the atmosphere as of this morning. The convective
activity really picked up with this last night, but that's partly
because it moved over warmer waters over 28 deg C. There is not much
wind shear at the lower-levels of the atmosphere, but there is at the
higher levels. The large scale pressure field from yesterday shows that
the High Pressure over the Atlantic covers most of the northern
Caribbean (including Jamaica) which means the track of this system (if
it develops) will be to the south - however, that may change. I will get
the overnight pressure maps this afternoon and send out an update. It is
impacting the southern windward islands already, and given the pressure
fields, it won't impact the VIs so you guys are groovy. They plan to
send a plane into the system this afternoon to check it out so I'll
report back after that.

The Blobette (another technical term :) ):
There's an area of convection just off the coast of Tampa/St. Petersburg
(where I am). And yes, my skills in observation do show some dark clouds
overhead when I look out of my window. Wow... I must be a scientist!! ;)
There is a little circulation but is extends across the entire FL
peninsula (E-W) and given the proximity to land it is not too likely to
develop. But having said such rash statements before, I will be keeping
an eye on it... as can anyone who lives in Florida by looking outside.
The troubling part is not so much on the west side of Florida, but the
east side where the really warm Gulf Stream is - that's also an area to
watch out for by everyone one the eastern sea-board. To develop or not,
in either case it looks like some lovely stormy weather here.
Yippeee.... :)

Tuesday, July 15, 2008

TS Bertha & The Blob: July 15 Update A

Well things are looking better all over the place today. Let's start
with 'The Blob' :).

The Blob:
The atmospheric circulation was not in this system in the manner I
normally see for a storm, although there was (and still is) some nice
convective activity - it's bark looked worse than it's bite. I will keep
an eye on it, but at the moment it doesn't look like it will amount to
much. There is no circulation anywhere in the atmosphere in the vicinity
of the convection and the NHC has reduced the probability that this will
turn into something. So this is my last entry on this particular blob.
Hopefully.

TS Bertha... the Never Ending Story...
It feels like a long 12 days since I started reporting on Bertha (a mere
Tropical Depression back then) and she's still a really strong TS with
winds of 70mph. I think she actually made cat 1 hurricane strength
yesterday given her structure and the amount of convective activity, but
there's very little difference between a strong TS (39-73mph) and weak
cat 1 (74-95 mph) with winds hovering at around 70mph. She has expanded
in area though, and she is moving over waters of 27-28 deg C with low
wind shear ahead of her. - signs that she may officially re-intensify a
bit.

She's now moving along faster than expected at 12 mph in a N-NE
direction, and will soon be heading NE, then E. The track (and computer
models) have her then turning SE tomorrow before she changes direction
once again and heads back NE on Friday. The reason for this convoluted
path: although she is currently moving clockwise around a high pressure
system (because this is the northern hemisphere), there is a low
pressure system digging in from the north. So the "clock-face" she is
following around the Atlantic (see

http://jyotikastorms.blogspot.com/2008/07/jyohurricane-tropical-storm-bertha-july.html

for clock-face explanation) is not as round as we are used to - it is a
little Dali-esque clock with wiggles and whatnots (technical terms ;) ).
That is why her track brings her back south tomorrow.

The research cruise did leave Bermuda this morning and they are
currently E-SE relative to the island. From the ship: "Nice 15 knt
breeze and the swell even." Just 6-8ft seas according to our intrepid
reporter. Fortunately they are not going too far east ... otherwise
guess who they might bump into in a couple of days? :)

That's all for today I expect - but there will be more on Bertha tomorrow.

Have a wonderful day, wherever you are. And of course, if you have
questions... I can try and find someone to answer them for you ;)
J.

Blogs archived at: http://www.jyotikastorms.blogspot.com/
-------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and the
National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.
-------------------------------------------

Monday, July 14, 2008

TS Bertha and The Blob: July 14 Update B

Hmmm... "TS Bertha and The Blob", now there's a movie just waiting to be
made. A romantic comedy perhaps.

Tropical-Storm-I'm-almost-a-Hurricane-again Bertha:
The warm surface waters around Bermuda that I mentioned this morning are
proving to be a stronger factor than the wind shear (which is still to
her north), so she intensified whilst passing over Bermuda and will most
likely become a Hurricane before the day is done (and before she's
finished hanging about Bermuda). Although her eye is north-east of the
island (33N, 64.1W), the southwest quadrant is where the really strong
convection is happening - right over both the island and water
temperatures of over 29 deg C.

I got a report from Bermuda at 11.30 this morning saying it was "just a
wet windy day"... and then one at about 3.30pm saying "now its a
storm!". The official NHC 5pm advisory still has her as a Tropical
Storm, but barely. Her maximum sustained winds are about 70 mph (TS
winds: 39-73mph) so she's a strong TS. She is heading northward at 9mph
and will begin to turn north-eastward tomorrow. I'm not sure about the
south-eastward turn that the computer models are predicting in a few
days time, but as I said earlier, it's academic at that point because
it's out in the Atlantic.

Let me tell you, those folks on Bermuda are a hardy bunch. I just got an
email as I was composing this, sent at 4.45pm: "It's teeming with
sideways rain. my umbrella was a victim. walking home was
interesting."... followed by "the happy little Bermudian tree frogs are
singing in the rain (and wind)."

So ummm... enjoy your research cruise scheduled to depart from Bermuda
at 7am tomorrow... (I have an inkling that it may be postponed another
couple of days -shh... don't let them know) ... have another cup of tea
folks, or maybe its time for something stronger to match the stronger
storm - which I expect is your preference too.

Everyone else, raise your hands if you are tired of Bertha and would
like to talk about something else? Ooh.. a number of you. Well this is
your lucky day...

The Blob:
The circulation in this blob (technical term meaning... a blob ;) -
something I call a region of unusual convection) that some of us have
been watching over the past few days has improved. The convective
activity decreased a bit this afternoon and cloud tops are warmer now,
but there is more rotation (or vorticity if you like). Interestingly,
the rotation is (at the moment) confined to a height of 2-3km in the
atmosphere - it's not at the surface and it's not any higher, so this
system is still very much in the developmental stages. The NHC have not
yet called it a Tropical Depression, but it is moving in a W-NW
direction at 15 mph.

The circulation appears to be centered somewhere around 12N, 43.5W,
along with the convection. The pressure fields are changing a little
bit, so this could pass into the Caribbean at any place (if it continues
to develop) - including the northern end. I just wanted you VI people to
be aware and keep an eye on it - as if you weren't already! It could
also still head towards Jamaica. At this point it really is too soon to
tell. It's over water temperatures of 27-28 deg C and in a low
wind-shear environment so something to watch.

I hope those of you in Bermuda stay safe. I look forward to hearing from
you after the storm passes.
Toodle pip for now,
J.

Blogs archived at: http://www.jyotikastorms.blogspot.com/
-------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and the
National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.
-------------------------------------------

Tropical Storm Bertha: July 14 UpdateA

TS Bertha:

She finally made a move yesterday and has slowly gained speed. Phew. She's
now moving in a N-NW direction at 8mph, and is centered at 31.6N, 63.5W.
This brings her current location to be about 70 miles SE of Bermuda, which
is within the TS system. She is moving around that high, which finally
"got out of the way" (technical term), so the northward turn later today,
followed by a north-east turn is all very reasonable (clockwise around a
high pressure in the northern hemisphere). The models have her doing the
whole N, then NE turn, and then their track shows a SE motion - I have to
look at the pressure fields later today to see if I agree with that - but
it's all out in the Atlantic at that point.

As I said a day ago or whenever (the Bertha entries are all blurring into
one another by now), because she's moving a bit faster she is encountering
warmer waters of 27 to over 29 deg C, so there will be some more
convection than there was in the system when she was stationary. However,
just to her north the wind shear picks up, so although she's a strong
Tropical Storm with 65 mph winds (TS: 39-73mph), she may not regain
hurricane strength. I expect they'll need their raincoats and wellington
boots (British-English :)) in Bermuda today. And maybe a cup of tea as
well.

The "Blob" (another technical term):

Yes folks, those who were reading this last year, this is "The Return of
the Blob" (the 2008 edition). :)

There's a mass of convective activity at around 10N, 40W - mid-Atlantic,
and it's heading westward. Some of you have already asked me about it, so
I'm starting the entries for this now instead of waiting until they
designate it a Tropical Depression or TS. There is not a lot of
circulation at the moment (and has not been) connected with the actual
areas of heavy convection. The circulation is at ~10N, 37W. I know the NHC
have designated this as a high potential area for storm development, but
until we start to see some real rotation (vorticity) in the area of
convection, it could go either way. One possible track if it develops is,
indeed, towards Jamaica. I think the VIs should be fine - it looks like
the pressure (as of yesterday anyway) would keep it to the south.

I'll send out another update on both of these later today.
J.
Blogs archived at: http://www.jyotikastorms.blogspot.com/
-------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and the
National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.
-------------------------------------------

Sunday, July 13, 2008

Tropical Storm Bertha: July 13 Update A

The cooler waters underneath Bertha that I mentioned yesterday are taking
their toll on the storm and she now has winds of 65mph, making her a
Tropical Storm again (wind range: 39-73mph). Also as previously mentioned,
the greatest convective activity is in the northern section of the storm
where the waters are still over 27 deg C. However, she has not really
moved in the last 24 hours - she was at ~30N, 62.5W then and now the NHC
says she's at 30.2N, 63W. So I expect that those waters are becoming
cooler too. The NHC says she is moving NW at 2mph, but looking at the
satellite images it looks like she's still just more-or-less hanging out
in the same spot - I suppose, to use an American phrase, one could say
she's "chillin' out" ... in more ways than one :).

The eye is not as clearly defined which makes it a little difficult to
pin-point the exact center. A plane is going in this afternoon to
investigate the system so we will get a better idea of where her center of
circulation is later in the day.

Despite the lack of an eye she still has a really good circulation. There
is finally some wind shear ahead of her, and although the waters around
Bermuda are over 28 deg C, the warm water is pretty shallow. Therefore,
her intensity should not change too much. The slower she moves, the less
likelihood of her intensifying any time soon because she is already
impacting the water temperatures beneath her.

For those following the cruise soap-opera ("The Young and the Certainly
Restless" or maybe it should be "As the Water Turns"): The research cruise
departure has been postponed again and will leave on Tuesday morning. This
is better than a Monday morning departure, but, well... it does look like
she will be a tad closer to the island than the forecasts were saying
yesterday and if she doesn't start moving northward (or even just moving
actually) then Tuesday may cutting it a bit fine. The current marine
forecast for Tuesday morning, if Bertha is correctly forecast to be at
~33.5N, 63.5W:

SEAS 12 FT OR GREATER WITHIN 240 NM NE...210 NM SE...120 NM SW...AND 210
NM NW QUADRANTS. HIGHEST SEAS 22 FT.

Bermuda is at ~32.3, 64.8W so it will be in the SW quadrant of the storm.

Let's see if she decides to do something later.
Later gators,
J.

Blogs archived at: http://www.jyotikastorms.blogspot.com/
-------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and
the National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.
-------------------------------------------

Saturday, July 12, 2008

Hurricane Bertha: July 12 Update A

After working hard all week, Bertha is enjoying a relaxing weekend -
just like me :).

She is very slowly drifting northwards at 2mph. Her central pressure is
983mb and she has winds speeds of 80 mph, which still keeps her as a cat
1storm (74-95mph). Even though she is supposed to be over water
temperatures of 27-28 deg C, because she has been almost stationary I'm
sure the water temperatures beneath are a bit cooler by now. In some
images you can see the path she took as she crossed the Atlantic because
the sea surface temperatures in her wake are cooler than the surrounding
waters. So, with what we assume are cooler waters below, it is unlikely
that she will intensify much until she starts moving again and at that
point we'd have to assess what the atmosphere is like as well to figure
out if she will re-intensify at all.

She is now almost at 30N, 62.5W. Wind shear is still low, and the
convection is not very symmetrically distributed. Her cloud tops are
fairly warm in large parts of the storm. The northern edge has the most
convective activity (and cooler cloud tops) at the moment - that is
where she is interacting with the warmer water ahead of her. For a reminder
explanation of cloud tops look at the July 9, update C in the archives.

I hear the Bermuda research cruise departure has been postponed to
Monday morning... right around the time when Bertha will be closest to
the island if she continues as forecast. What are the waves now... 10ft?
That should be oodles of fun.

I won't send out another update today unless there's some change.
Bye for now,
J.

Blogs archived at: http://www.jyotikastorms.blogspot.com/
-------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and
the National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.
-------------------------------------------

_______________________________________________
Jyo_Hurricane mailing list
Jyo_Hurricane@marine.usf.edu
http://seas.marine.usf.edu/mailman/listinfo/jyo_hurricane

Friday, July 11, 2008

Hurricane Bertha: July 11 Update B

It looks like she's made that little bit of a northward turn and is
"zipping along" in a N-NW. Now when I say "zipping along" I mean moving
forward at a fast pace relative to a snail... she's got a grand forward
speed of 4mph. She is encountering that high pressure and the poor
little thing is struggling really hard to move northward. Umm... but
this doesn't necessarily mean that she will avoid Bermuda altogether.

She's intensified slightly since this morning and now has winds of 90
mph (compared to the 85 mph earlier), but this still makes her a strong
cat 1 (wind range 74-95 mph). They finally sent in a plane to
investigate the storm this afternoon and have much better observations
on what is going on. Her central pressure is 976mb. The NHC do not
forecast a strengthening in the next few hours - although they have said
there is a possibility. I think it is very likely that she will become
stronger! She is already looking better, with stronger convection
occurring all around the eye (although the eye could do with some
polishing up yet). She is over water temperatures of 27-28 deg C,
although the depth of those warm waters is quite shallow. She is also in
a low-wind environment - all these indicate some further intensification
to me.

The other thing I do not agree with the NHC about at the moment is me
is that she will weaken in 36 hours as she moves over cooler temperature
...of what, 27-28 deg C?? - unless she picks up forward speed very
rapidly, or makes a sharp right turn and moves quickly I don't see the
'cooler temperature' waters they are referring to. As for picking up
speed, the models have her pretty much just loitering about
(mischievously of course - can one loiter any other way?) for a day or
two as she tries to get past this high. Scenario one from yesterday -
getting swept along that low pressure system - is not going to happen.

Meanwhile, back on Bermuda ... our intrepid reporter told me they loaded
the research vessel in preparation for departure in a couple of days and
now he's off to play a round of golf. Dum-de-dum... another normal day
in Bermuda (other than the tropical storm watch and closing of the south
beaches).

Have a wonderful weekend (this hopefully applies to people in Bermuda as
well). Unless something exciting happens tonight, I'll send something
out tomorrow.
Bye for now,
J.

P.S. I know a lot of new people have been 'dropping by' and reading this
so if you have any questions (or I am being incomprehensible :) ), then
do let me know.

Hurricane Bertha: July 11 Update A

There wasn't much change in Bertha's track or intensity yesterday... she
has winds of about 85mph and is therefore still a mid-sized cat 1 (wind
range: 74-95mph), and she continues to move in a NW direction.

She did slow down, and is now chugging along at about 6mph, which
indicates that she continues to bump up against a higher pressure region
in front of her (was it the Little Engine That Could that went slowly up
the hill or was it Thomas the Tank Engine?). Although there is still an
eye, it is not as well formed as it was 24 hours ago. But there is good
circulation in this system, now extending into the higher levels of the
troposphere (lowest level of the atmosphere). Despite the nice
circulation the convective activity is not very well distributed and
this morning it is mostly on the west side. Without better observations,
the best guess (mine, the NHC, the models) is that she will remain a cat
1 today.

She's currently at about 28.2N, 61.7W and the computer models are in
agreement that she will continue her NW track until she is at about 30N.
After that point they diverge, but all remain on the east side of
Bermuda. Some even forecast that she will stall. The NHC will probably
issue a Tropical Storm Watch for Bermuda later today.

I am waiting for her to get to about 30N before I can assess which of
the three scenarios I presented yesterday will really kick in. Until
then, she's going NW and towards Bermuda.

She is in a region of low wind shear, and also over water temperatures
of about 27-28 deg C. But just north of 30N, she will encounter warmer
temperatures of 28-29 deg C.

There is insufficient data to be able to make a really good call on her
track at this point - and this is the problem with both the track and
intensity forecasts. There are not enough observations at a high enough
resolution. With the right type of data at the right resolution,
hurricane forecasts would be much improved... and then you'd all have
more time to do interesting things like washing your hair or watching
the grass grow instead of reading this blog :)

For those wondering what those hardy Bermudians are going to do about
their research cruise - last I heard it had been pushed back to Sunday.
Maybe I'll get an update today... and if they do go out, we might get
some live "in the field" reports. I suppose it's one way to lose weight...

More later,
J.

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Thursday, July 10, 2008

Hurricane Bertha: July 10 Update A

I should never have called her Boring Bertha a few days ago. I'm sorry
Mother Nature. I take it back.

Intensity:
So... the Really Very Incredibly Interesting Bertha is now weakening
again and has winds of 90mph, making her a strong cat 1 (74-95mph
range). I hope you all remembered my 'warm cloud top' discussion from
yesterday? Well, that was a sign of the weakening, and since then the
cloud tops have become warmer so there is not a lot of convective
activity going on in this system. She is still surrounded by dry air,
and some of that is getting entrained. However, she is still over waters
of 27-28 deg C and in a low wind-shear environment, and dynamically she
is still very good looking (she still has an eye), so I am not sure if
she will weaken much more today and she there is a good possibility that
she'll get a bit stronger - and that is also the thinking of the NHS,
who are finally not solely relying on the models:

"THE INTENSITY FORECAST IS A CONUNDRUM. <talk about models>... THE
INTENSITY FORECAST WILL BUCK THE MODEL GUIDANCE AND CALL FOR SLIGHT
STRENGTHENING DURING THE FIRST 24-36 HR."

Track:
This is also becoming trickier by the hour. Given her slower forward
speed of 9mph it looks like she is moving against an area of higher
pressure (going up hill slowly). There are three scenarios:
1. there is now an area of low pressure moving off the US and into the
Atlantic. IF that moves fast enough and she gets north enough in the
next day or two, she will interact with it and move northward - but
where exactly that interaction will occur is uncertain. However, the
computer models at the moment are predicting that she will not interact
with this low.
2. she manages to get around the high she is now bumping against and
moves N-NW and then N soon
or,
3. she will continue to move in a NW direction and to the west of her
current track as she tries to get around this high pressure system
(remember, in the Northern Hemisphere, things move clockwise around a
high pressure system).

Her forward speed provides a clue about the state of the atmosphere -
slower speeds indicate that she is encountering a high pressure ahead of
her, and so the chance that the track will be to the left of the current
center of the cone is greater.

Let's see what happens during the rest of today.

I hear that the surf is now good in Bermuda - and tomorrow the east
coast of Florida should see some nice surf...
J.

Wednesday, July 09, 2008

Hurricane Bertha: July 9 Update C

Big Beautiful Bertha - she's now a large cat 2 with sustained winds of
105 mph and a minimum pressure of 970 mb (cat 2 winds: 96-110mph). She
is back on a NW track and is moving at 12 mph - so although the track
east of Bermuda is still looking like a good scenario I would make
preparations though (and I don't mean cruise preparations!) because she
will grow, and the track forecast is still dodgy after tomorrow - we now
need her to make that N-NW turn and sustain it, and the sooner the
better. She's at lat. 24.8N, 58.1W, still surrounded by dry air, but
hanging out over water temps of 27-28 degc C and in a low wind shear
environment.

Interestingly, for such a good looking and strong storm her clouds tops
are fairly "warm". What does that mean? It means that the tops of her
clouds are not as high up in the troposphere (the lowest section of our
atmosphere) as they could be. The troposphere is characterized by
cooler air temperatures the higher up you go. So the higher the clouds,
the colder their tops, and that's an indication of some very very strong
(or deep) convective activity (large thunderstorms etc). If you look at
a color infrared image of a hurricane (there are some in the "satellite"
link on left side of the NHS webpage), the coldest clouds tops are
indicated by red. The last time Bertha was this size a couple of days
ago, if I recall correctly, her cloud tops were cooler - and they
certainly were red when she was a cat 3. So she is not yet as deep into
the troposphere as she could be.

That's all for today (unless there's any major change tonight).
Ciao,
J.

P.S. I know the blog/wrap-around text problem did not get resolved -
we'll try something else tomorrow. Oh well... it still looks nicer than
it did. :)

Hurricane Bertha: July 9 Update B

Bertha is getting Bigger. Again. Deja vu anyone?

In the 11am advisory, about 2 hours ago the NHS kept Bertha as a cat 1
storm (which I agree with) with about 75mph winds (which I disagree with
- I think they were stronger, even back then) and a central pressure of
987mb.

Intensity: She is intensifying again and an eye has formed. She may even
become a cat 2 by the end of today because she is back to being
Beautiful Bertha. There's a chance for a cat 3 too, but that sort of
very rapid intensification is currently difficult to predict. She is
over 27-28 deg waters in a low wind shear environment (other than to her
north-east) and is not only growing in intensity, but also in size
despite the dry air surrounding her.

Track: She is now officially heading in a W-NW direction at 12 mph and
is located at around 24.5N, 58W so she is ~700 miles SE of Bermuda. It
is a little tricky to judge, but they may have shifted the track a
little to the west - the next advisory at 5pm will be a bit clearer I
think. We really are looking for her to resume that NW motion, and then
N-NW so she stays east of Bermuda.

Both the track and intensity forecasts are now a little dodgy after the
next day or two - the models are not quite as tightly confined as they
have been so far. I am not too surprised by this.

For those following what's going on there from my previous entry - the
research cruise has now been pushed back to Sunday morning. Currently
the forecast is for Bertha will be in the vicinity Sat/Sun...

I'll send out another update later, after the 5pm advisory.
J.

P.S. For those of you looking at the blog on the website, thanks for
complaining about the format of the text (AA) ;). Coincidently, my
wonderful web-guru and pal, CH, decided he needed to take action as well
because otherwise I'd never get anywhere. So I am hoping this entry will
look much nicer than all the rest. I've also added some
hurricane-related links to the site now. And one day, I may even be bold
enough to add an image! (I can hear your collective gasps of amazement
you know) - but let's not rush into this fancy-schmancy technology too
quickly hey? :)

Hurricane Bertha: July 9 update A

Building Bertha - I know, I am scrapping the bottom of the barrel here are
for alliterations. If I get them all out now, you may be spared from such
silliness later in the season. Or perhaps not :) Right... down to
Bertha-Business:

Intensity:
The 5AM NHS advisory this morning says that Bertha looks like she is
getting better formed and the vertical shear may be decreasing - which is
what I said yesterday. Despite a better looking storm (much better than
the 'cat 2' they had her at yesterday), they have continued to lower her
wind speed to 75 mph, so barely at hurricane strength (cat 1: 74-95mph). I
do agree with her cat 1 status and I think that we'll see some
intensification to a strong cat 1, also in agreement with the NHS.
Although still surrounded by dry air, the water underneath is 27-28 deg
C., and she is in a region of low wind shear.

Track:
So far the track models have been pretty good as they have forecast her
move around the clearly defined Bermuda/Azores High. They still keep her
to the east of Bermuda - moving past in about 4 days - but I am not as
certain of this as I was yesterday. She's at 23.5N, 56.5W, her forward
speed has slowed down to 10mph, and the NHS say she is moving in a NW
direction. I did some quick calculations (because I'm a geeky scientist)
and it looks like she is moving more on a W-NW trajectory now and has been
since yesterday - this brings her track closer to Bermuda (~lat: 32.3,
long: 64.8W) so we may see the envelope shift westward.

The track forecast may be about to get a bit more complicated though, as
there is a second high pressure system moving off the US into the
Atlantic. The ideal situation is for Bertha to pass between the two high
pressure systems (in a lower pressure area known as a trough), but because
she is slowing down I am wondering if she is actually already interacting
with this second high, which will continue to keep her west of the current
forecast track - hence the possible westward movement of the track
envelope. I don't have a fine enough resolution pressure field to be able
to see this so we will have to watch what happens in the next 24 hours.

So, to sum up: if you are still planning on a research cruise on Saturday
out of Bermuda the most helpful advice I can provide is... don't forget
your sea-sickness aids :)

Another update later...
J.

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Tuesday, July 08, 2008

[Jyo_hurricane] Hurricane Bertha: July 8 Update B

I was disappointed with the NHS forecast earlier today. At 11am they
downgraded Bertha to a cat 2 (winds of 96-110mph) when she was clearly
far less than that by 9.30am this morning with no eye, not very good
convection etc. So for the past six hours she was officially and wrongly
classified as a cat 2, which troubles me. However, the latest 5pm
advisory has her as a cat 1 (winds of 74-95mph), which I agree with.
The NHS acknowledges that their intensity forecasts have been way off.

She is now at 22.7 N, 54.8W and heading NW at 12mph. Maximum winds are
85mph and they forecast continued weakening in the next few hours but
keep her as a cat 1 for the next two days. To me, she looks like she has
intensified slightly since this morning (which is why I agree with their
cat 1 assessment) and she is now back over warmer waters of 27-28 deg C
and is entering a region of lower wind shear. Dry air is still being
entrained into the storm, but she is trying to regain some of her steam
(all puns always intended :) ).

It still looks like she will pass east of Bermuda, but you Bermudians
should still keep an eye out in case something happens that wasn't
forecast - although really, how often does that occur, hey?... umm...
never mind.

I hear that the surf will be wonderful over there soon...(and suddenly
all flights to Bermuda are fully booked). By the way, I had no idea how
many people were surfers on this list. Let me know if you would like me
to introduce you to each other. :)

If there are any major changes I'll send out another update later,
otherwise until tomorrow amigos...
J.

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[Jyo_hurricane] Hurricane Bertha: July 8 update A

Although she's still officially a strong hurricane, I think she's going
to be Tropical Storm Bertha (39-73mph) in the next NHS advisory, or at
the very most a cat 1 hurricane (74-95mph). In the last ~6 hours, she
has steadily collapsed from being a strong cat 3 storm (111-130mph) with
winds of 120 mph and central pressure of 955mb to a system that does not
have an eye, has poor convective activity and is entraining dry air. She
is still over waters of 26-27 deg C, but has entered a region of higher
wind shear.

She is also going to pass well east of Bermuda - which is what I thought
and it is also in agreement with the computer models. The current center
of the cone will be shifted eastward again. At the last advisory she was
moving to the NW at 10mph - I think she's now moving N-NW.

Once again, the official intensity forecasts are 'a bit off' - they had
her maintaining cat 3 status throughout the day today, dropping to a cat
2 tomorrow. Given her collapse and surrounding atmospheric
environmental conditions I don't see her re-intensifying to a cat 3, and
I expect the NHS to downgrade her quite rapidly in the next couple of
hours. This storm has really demonstrated the amount of work that still
needs to be done in order to get a handle on the intensification of a
tropical storm.

I will send out another update later today. Have a lovely day :)
J.

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Monday, July 07, 2008

[Jyo_hurricane] Hurricane Bertha: July 7 update C

I think Bertha is having fun with the intensity forecasts being made :)
- although forecast to be a cat 2 in the 11am advisory, the 5pm NHS
advisory has her as a major hurricane category 3 storm (winds range:
111-130mph). Her wind speed is now 115mph, which is quite remarkable for
a storm that is surrounded by dry air and only over water temperatures
of 26-27 deg C. (she's moved back over slightly cooler waters since my
last update). She's at ~20.2N, 52.1 W and is moving W-NW at 12mph now,
so she has slowed down quite a bit. Minimum pressure has dropped to 948 mb.

The track is still something to keep an eye on, but it does look like
she's moving more northward of the official W-NW heading which will take
it east of Bermuda, but just in case... if you are in Bermuda, I hope
you are getting ready!

That's all for today folks. More tomorrow.
J.

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[Jyo_hurricane] Hurricane Bertha: July 7 Update B

Beautiful Bertha gets Bigger (how's that for a news headline? am I in
the wrong field? :) ) ... she has intensified and the NHS now agrees
with what I wrote earlier - she will continue to intensify and become a
cat 2 (wind range: 96-110mph). Their next advisory is at 5pm, but it
looks to me like she is already a cat 2. The last advisory at 11am had
her with 90 mph winds and she was a smaller, weaker storm at that point.
Her diameter has grown quite noticeably in the last few hours, with a
solid ring of convection around a very clearly defined eye - she really
is a good looking system. There is still wind shear to the north-east,
which is why if you see a satellite image of her (for example,

http://www.ssd.noaa.gov/goes/flt/t1/vis.jpg), you will see a stream of
activity extending off her north-east quadrant. But despite that and the
dry air surrounding her, the low wind shear around other parts of the
storm and the warm waters underneath are really kicking in.

This storm is great and well-timed for two reasons:
1. It demonstrates that we (as a hurricane science community) still do
not fully understand what makes tropical storms intensify because if we
did then the models would have forecast this intensity, but as late as
24 hours ago they were still predicting that today she would be a
Tropical Storm.
2. Although the models improve every year, this gives us a benchmark for
the rest of the season as far as the intensity models are concerned, and
for this year their forecasts may still be off within any 24-hour window.

She's at about 20N, 51.5W, moving W-NW at about 15mph with a central
minimum pressure of 975 mb. Interestingly, the circulation still does
not extend up through the entire troposphere. The troposphere is the
lowest section of our atmosphere and in the tropics it extends to about
16km above the earth's surface (oooh... aaah... science :) ). There is
now, however, a clear circulation (vorticity) at the mid-levels of the
troposphere. The really large storms have a clear circulation all the
way to the top boundary of the troposphere, which is called the tropopause.

I'll probably send out another update after the 5pm advisory is out.
Isn't this exciting? :)
J.

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[Jyo_hurricane] Hurricane Bertha: July 7 update A

Great googliemooglies... I knew as soon as I called her 'Boring Bertha'
that she would start to change - it was like throwing down the gauntlet.

Although she is a hurricane (cat 1 wind range 74-95mph), she was barely
one when they upgraded her from a TS to a hurricane early this morning.
The wind speeds are calculated from satellite information, not from in
situ data within the system, so they are not very accurate. The discussion
from the NHS this morning says:

"OBJECTIVE DVORAK ESTIMATES REMAIN SLIGHTLY BELOW THE HURRICANE
THRESHOLD...BUT GIVEN THE MICROWAVE SIGNATURES THE SYSTEM IS UPGRADED TO A
HURRICANE..."

The Dvorak technique is used to estimate the wind speed from satellite
data. Although their calculations showed winds of slightly less than
hurricane strength, the images showed an eye so she was upgraded. I'll
ramble about the Dvorak technique in a later entry.

In this case we were all wrong - the NHS (and models) yesterday forecast
her to reach hurricane strength 24 hours from now (Tues am), and I did not
think she would quite make it and would remain a very strong TS.

She is now at about 19.5N, 50.5W and is moving in a W-NW direction at 17
mph. She will clear the Caribbean, but how far west she moves before
curving into the Atlantic is still debatable. The reason the system is
slowing in forward motion is because she is bumping up against that high
pressure - it's like anything moving up a hill, a bit slower depending on
how steep the gradient is.

There is a well-defined eye and she is looking good: Beautiful Bertha :)
The circulation is not very deep into the atmosphere, so although she
looks good, she is still a very weak cat 1.

She is almost completely surrounded by dry air, so the moisture is
predominanatly coming from evaporation from the ocean. Temperatures
underneath are 26-27 degs C, but within a few hours she will be over water
temperatures of 27-28 deg C, and given the slower forward motion and her
recent intensificaton, it looks likely that she will get stronger. The
wind shear is not very high this morning (except at the north-eastern edge
of the storm) and it does not look like it will get much stronger in the
next 24 hours. The NHS forecast keeps her as a cat 1 storm though.

In 1996 a previous incarnation of Bertha became a Hurricane on July 7.

More later today.
J.

Blogs archived at: http://www.jyotikastorms.blogspot.com/
-------------------------------
DISCLAIMER:
These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and the
National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run
away, run away" (Monty Python), I'll let you know.
-------------------------------------------

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Thursday, July 24, 2008

Wednesday, July 23, 2008

Tuesday, July 22, 2008

Monday, July 21, 2008

Sunday, July 20, 2008

Saturday, July 19, 2008

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Thursday, July 17, 2008

Wednesday, July 16, 2008

Tuesday, July 15, 2008

Monday, July 14, 2008

Sunday, July 13, 2008

Saturday, July 12, 2008

Friday, July 11, 2008

Thursday, July 10, 2008

Wednesday, July 09, 2008

Tuesday, July 08, 2008

Monday, July 07, 2008

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