Wednesday, August 06, 2014

Tropical Storm Bertha: August 5, Update A

Ahh... ice cream. The current favourite is Mud Pie. So delicious I might have to have another bowl to er... help me write.... :-)

Tropical Storm Bertha is now pretty weak with winds of 50mph (TS range: 39 - 74mph), central pressure 1007mb. She is officially centered at 37.5N, 68.1W heading NE at 23mph, but it is difficult to identify an actual center.

She's not really a Tropical Storm anymore even if she is bringing a bit of wet and windy weather with her...

Apart from not being able to see much of a circulation in the satellite imagery, we can also check the vorticity maps (I'm sure you memorized every brilliant word I wrote on this yesterday! ;-)) to get an idea of her structural integrity. Near the surface (850mb) she no longer has a self-contained red 'splodge' (don't be fooled, this is still a highly technical term ;-)) but is attached to another red splodge (splodges unite!) (ok, I admit it, I just like saying the word 'splodge' ;-))...

Same for the next level up (700mb) except the colors are a little weaker ...

And there's really very little going on in the middle troposphere (500mb)...

These all show that her structure is not really circular like a storm, but elongated like a front with two areas of stronger activity, which we can also see in a larger satellite image of the Atlantic:

The vorticity maps also show that she doesn't extend high into the atmosphere, so she is, indeed, a fairly weak system compared to a hurricane. But as a front, she can still bring some wet and windy weather... and it looks like she will to those in the UK area! Best put the deck chairs away!

<Technical Alert!> If you want to look at these maps for yourselves, go to the University of Wisconsin website for the Atlantic winds: http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=.

This will show you the map at 850mb. To look at the maps at the other levels, along the top are a number of tabs. Click on the level you want - 700mb, 500mb, 200mb.

These maps get updated every 3 hours, although you have to refresh the page each time. You can even go back to the map from 3 hours ago by using the tabs on the upper left. You can see a time stamp at the bottom, in the black border of the image.

There are a few more tabs at the top. Wind shear shows wind shear (are you surprised? ;-)). Wind shear tendency shows the direction the wind shear is heading in - so low tendency (dark blues) means that wind shear will not strengthen, and high tendency (reds and oranges) means that wind shear is likely to increase.

I'll go into upper level divergence and lower level convergence the next time we have a storm! (unless you have a super-amazing memory and really remember everything I ever wrote, in which case it is probably in an entry from last year :-)). <End Technical Alert!>

Meanwhile, over in the Pacific, we have TS Julio which has winds of 65mph and is still heading for the Hawaii region for the weekend, just a couple of days after Hurricane Iselle ges there (she has weakened to a cat 2 with winds of 100mph... I'm sure that's a relief to those on the islands!)...

(And in the western Pacific, Typhoon Halong is now down to a cat 1 with winds of 90mph, heading for Japan on Friday).

If Bertha is not downgraded tomorrow, I'll be back with another update - although it will be a bit late in the day because I'll be watching that scientifically accurate upcoming movie, Into the Storm (and then recovering from it). ;-) Otherwise, I'll back for the next storm (next name in the Atlantic is Cristobal) but I'll be tweeting about the other basin storms as usual in between.

Night night!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
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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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Tuesday, August 05, 2014

Hurricane Bertha: August 4, Update A

I'm going to jump right in today...

The NHC upgraded TS Bertha to Hurricane Bertha this morning. I think they overestimated her intensity and although she is still officially a hurricane, I have to say, I don't think she's been one for most of the day and certainly doesn't look like one now...
Currently her wind speed is 75mph, so she's barely a cat 1 (cat 1 range: 74-95mph). Central pressure is 1001mb. Although it looked like she was going to hang out in conditions that would allow her to grow a bit, she moved rather quickly over colder water! So although the wind shear is low and she's in an area where there is moisture in the atmosphere, we see the importance of the ocean at play... the sea surface temperature is around 27-28 deg C but there is hardly any warm water with depth; water warmer than 26 deg C is only in the upper ~25m. This would account for her scraggy appearance and structure.

She is apparently centered at 31.3N, 73.1W heading NNE 20mph. I really think she's a Tropical Storm and barely got to hurricane strength today. Of course she will continue to deteriorate as she moves north.

<Science Alert!> Although satellite images are one piece of the information puzzle, the biggest clue about what sort of storm we have is in the circulation (or vorticity as this is supposed to be all sciency stuff ;-)) and what that looks like at different levels of the troposphere - this gives us a glimpse into the structure of the storm. A tropical storm will have a well-defined circular "splodge" (yes, you can expect only the most highly technical jargon to be used here! ;-)) on a map of vorticity. The stronger the storm, the more cohesive the "splodge" at all levels of the troposphere.

Luckily for you, I have a Tale of Three Storms to show you this! :-) 'Hurricane Bertha' in the Atlantic, and both Hurricane Iselle and Tropical Storm Julio in the E. Pacific. Earlier today I grabbed the vorticity maps for the Atlantic and E. Pacific. At that time, Bertha was a cat 1 storm officially with winds of 80mph, Iselle was a cat 4 and had winds of 140mph (she is still a cat 4, but with winds of 135mph, still heading to Hawaii) and Julio was just a baby with winds of 45mph (he now has winds of 60mph, and is also heading in the Hawaii direction!).

We can see the how good the structure of these storms are throughout the troposphere by looking at the circulation/vorticity maps for four levels of the troposphere.

The lowest level, pretty darn tootin' close to the surface of the planet (850mb)...
Atlantic (Bertha, the really dark red splodge just to the right of the Bahamas):
E. Pacific (Iselle is the red 'splodge' on the left - actually, the center is white which indicates that the vorticity is really really strong - and Julio is the one on the right):

A bit higher (o.k., 700mb if you want to be all technical ;-))...
Atlantic (Bertha, the  dark red splodge next to the Bahamas):
E. Pacific (Iselle is the red/white 'splodge' in the center and Julio is the red one on the right):

The middle bit of the troposphere (500mb)...
Atlantic (Bertha, the not-so-dark-red-as-the-lower-levels-of-the-troposphere splodge next to the Bahamas, which indicates that although there is some vorticity, it is weakening as you get higher into the troposphere):
E. Pacific (Iselle is the dark red 'splodge' in the center and Julio is the one on the right):

And the upper troposphere (250mb)...
Atlantic (Bertha... no longer a splodge next to the Bahamas! which indicates no vorticity in the upper troposphere):

E. Pacific (Iselle is the round red 'splodge' in the center and Julio is no longer red splodge on the right):

For a hurricane, we always see a 'splodge' at all levels of the troposphere and they always line up on the same spot. The darker red the splodge is at the 200mb level, the stronger the storm. For a Tropical Storm, the vorticity generally stops somewhere in the middle troposphere (around 500mb), so both TS Julio and 'Hurricane' Bertha were really Tropical Storms, whereas Hurricane Iselle is most definitely a strong hurricane!

And thus endeth a Tale of Three Storms. :-) Let me know if you have any questions! :-) (All of these vorticity maps are from the University of Wisconsin... I'll show you how to get to them tomorrow). <End Science Alert!>

Before I zip off, I ought to mention this historic day... 100 years ago today (4th August, 1914) Britain and hence the Commonwealth jumped into The Great War, also known as World War I... or the largest family squabble in history (and you thought 'Dynasty' was bad?). Amazing times with many courageous stories!

Toodle pip!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
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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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Monday, August 04, 2014

Tropical Storm Bertha: August 3, Update A

A lovely Sunday with tea and Jaffa cakes and classic Dr. Who (the first one with the third Doctor, John Pertwee, is really good by the way :-)).

Meanwhile, over in the Atlantic things have also been moving along as suspected... Tropical Storm Bertha is still a Tropical Storm but has, indeed, intensified and now has winds of 65mph (1007mb central pressure). To re-cap from yesterday, this is because she's moved away from land (including the soggy Bahamas), wind shear has decreased (although there is still some), she's moved out of the dry and dusty SAL, and sea surface temperatures are now 28-30 deg C with waters warmer than 26 deg C.

She is not very organized at the moment but it looks like she will get stronger because all those conditions remain the same for the next day or so (wind shear will weaken a bit) and she'll probably be a weak hurricane tomorrow, which is in agreement with the NHC.

She is currently at 24.9N, 73.2W heading NNW at 17mph. The track looks more-or-less ok and she'll stay away from the US and Bermuda, possibly clipping Canada as a weaker storm in a few days:


So that's the Atlantic. Meanwhile, in the Pacific we have a few interesting things going on... the best looking of which is Hurricane Iselle, heading for a vacation in Hawaii on Thursday/Friday. She currently is a borderline cat 2/cat 3 (cat 2 range: 96-110mph, cat 3: 111-129mph) storm with winds of 110mph:

And in the West Pacific, Typhoon Halong is supposedly a border-line cat3/cat 4 storm because it has winds of 130mph, and is therefore stronger than Iselle. Although it is bigger, it does not have a very well-formed eye at the moment so I suspect it may be a bit weaker than a cat 4! (maybe a cat 2):

Not to be outdone by Iselle, Typhoon Halong is going for a vacation to Japan on Thursday/Friday. Japan really does not need more rain this week... I heard some parts had about 40 inches this weekend!

This large difference in the intensity of the storms (relative to their look) is because agencies from different countries issue the forecasts for storms in different parts of the world. Because they don't have enough data (or even the same sort of data) from inside these storms when they are over the ocean, it's pretty tricky for them to figure out their intensity (not for me, obviously, but I use magic ;-)  and I've been doing this for yonks!).

There are a few other blobs and blobettes in the Pacific, but that's all for now folks!

Until tomorrow,
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
-------------------------------
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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Saturday, August 02, 2014

Tropical Storm Bertha: August 2, Update A

Itsy bitsy Bertha is barely a Tropical Storm. She could be downgraded to Blobette Bertha and hardly anyone would notice, but officially the NHC have kept her as a Tropical Storm with winds of 45mph, central pressure at 1010mb as a precautionary measure. They said they couldn't find a center of circulation (or closed circulation actually)... and neither can I - can you?:
(Sorry about the satellite video loop - can't be helped!)

She does have a bit of convection though, with maybe the odd thunderstorm or two (shown as dark orange patches), as you can see in this infrared satellite image:

I received an on-the-ground report from our intrepid reporter, Tom, in St. Thomas:

"Short update from St. Thomas...first drop of rain at 6:41am with expectations of 6" by days end. Newly cleaned empty cistern awaiting the incoming...gusty wind but nothing like St. Croix to our south must be getting. Cats are in their hurricane beds behind hurricane shutters dreaming of gold fish and swooping birds...Bertha is a breeze!"

Bertha is currently officially centered at 18.9N, 69.1W, heading WNW at 22mph. This is somewhat speculative because, as I said, no-one actually knows the center. She is weak for three reasons:
1. She is interacting with the Dominican Republic, Puerto Rico etc. as shown in the satellite images, and this interaction will weaken her a bit more.
2. She is also in that area of dry, dusty Saharan Air Layer that I showed you yesterday.
3. There is quite a bit'o'wind shear.

The convection is because the water is rather warm - sea surface temperatures are 28-30 deg C, and the upper 100-125 m is warmer than 26 deg C.

Her future intensity depends on how much she weakens as she crosses out of the Caribbean. It is possible that she will begin to strengthen again as some of those inhibiting factors go away... you can see that she is almost out of the dry SAL layer and is moving towards a low-pressure area which has already got convective activity (over the Bahamas) in this IR satellite image:

Wind shear also looks like it will weaken once she is in the Atlantic, and the water temperatures are as warm as those in the Caribbean. All things that will allow her to intensify. The track keeps her away from the US, but it looks like she will roll over the Bahamas (who are already getting a coat of water).

I'll be back with more on Itsy Bitsy Bertha tomorrow!

Ciao!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
-------------------------------
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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Friday, August 01, 2014

Tropical Storm Bertha: August 1, Update A

I had a terribly busy week doing important things like painting my nails and drinking glasses of wine, but finally I have a moment to write!

I saw that the NHC upgraded a blobette to TS Bertha yesterday. I remember the last Bertha, 6 years ago... Big Beautiful Bertha. This Bertha is definitely not so big or beautiful at the moment. She's a dinky little thing with winds of 50mph (central pressure is 1007mb) and not much circulation or convection...



She is now in the Northeastern Caribbean, having crossed the Lesser Antilles earlier today, and is heading towards Puerto Rico. She is currently moving WNW at 24 mph (scampering along) and is currently at 15.2N, 61.9W (ish). The track forecast looks good to me.

The convection is to the north and east of the center, as you can see, so it looks like you guys in the VIs might finally get a spot of rain. Good news, hey? Just bring the cats indoors... apparently some of them don't like water. ;-)

Although sea surface temperatures are a rather warm 28-29 deg C, with warm waters in the upper 100-125m, I don't think she will intensify much in the next couple of days because there is some nice wind shear and she is still moving in oodles of dry and dusty air (known as the Saharan Air Layer) which you can see in this image as the lovely orange 'stuff' (technical term ;-)):


<Really Obvious Jargon Alert!> Saharan Air Layer (SAL): This is dry dusty air blowing off northern Africa (the Sahara Desert to be precise, in case the name didn’t give that away ;-)) and usually inhibits storm development. <End Really Obvious Jargon Alert!>

Once she moves away from the SAL and away from the Puerto Rico 'landmass' area, then she may intensify a bit more. Although I'm estimating this will take a couple of days, she is moving quite fast so we may see some intensification later tomorrow/early Sunday.

Good luck out there! More tomorrow.

Toodle pip!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
-------------------------------
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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Wednesday, July 23, 2014

Tropical Depression 2: July 23, Update A

I thought it was about time to jot down a bon mot or two on the latest blobette. :-)

I have been watching the mini-blobette (officially known as TD2) as she left Africa and zoomed across the Atlantic. She has been struggling, and at the moment there is very little circulation in the lower half of the troposphere and the convection has just decreased:


She is currently centered at 13.9N, 53.2W and is moving WNW at a very rapid 20mph. This blobette really doesn't have much to it, so it's pretty tricky to see where the center is actually and this location is as good as any other.

She is heading to the Lesser Antilles, and the folks there should be getting ready for it by making sure they have enough fixings for their umbrella drinks. It should be a lovely breezy day, maybe a little overcast with a drop or two of rain.

The forecast is for this system to dissipate any moment now and just be a low pressure trough by the time it moves over the Lesser Antilles. There are a couple of reasons for this. First, the wind shear is not very high, but high enough to hinder this blobette from getting the curling iron out. And second, the blobette is running into a bit of dry air:


(I don't know what they did to the colours of the normal water vapor map because these are horrible). The dry air as that dull dirty icky yellow shaded stuff.

However, so far she has been moving over relatively cold water (sea surface temperatures of less than 26.5 deg C - the temperature needed to sustain a storm). She's about to enter an area where the water temperatures are warmer than 26.5 deg C, with the upper ~100m being warmer than 26 deg C. This should sustain the convection at least and there is a chance she'll have more than one or two drops of rain as she crosses the Lesser Antilles.

I do agree with the NHC that she is too weak to amount to much, but I am still going to keep an eye on her. I'll be back with more if she does strengthen, otherwise I will spend the time watching really old black and white episodes of Dr. Who. :-)

Cheerio for now!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
-------------------------------
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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Saturday, July 05, 2014

July 4: Hurricane Arthur, Update A

Happy Independence Day America! A historic day indeed! In honour of today I won't mention that apple pie was an English dish from at least the 1380s or that baseball was played in England in at least the 1740s. Instead, because I'm a nice person (grin), here's a completely different fun fact for you: In 1776 some of the founding fathers (and mothers) of America were as old as Millennials are today (Millennials were born between the early 1980s and 2000)! Details here.

'Hurricane' King Arthur (he's not really one anymore as you will see) is officially at 41.2N, 68.7W, moving  to the NE at a whopping 31mph! This is too fast for a tropical storm and is the first indication that he is no longer a tropical storm, but is an extratropical system and has merged with a low pressure front.

His winds are 75mph, central pressure is officially still 976mb. Although 75mph winds means he is officially a weak cat 1 storm, but I agree with the NHC today because they have actually already said that he isn't a hurricane and have explained that they are being generous with this estimate of winds speed for now. When a storm merges with an extratropical front and has such a fast forward motion, one would expect high winds, even if it isn't a tropical storm/hurricane any more.

The satellite images clearly show how Arthur's appearance has changed over the last few hours:
 


The hint of an eye he had has vanished, his structure and circulation has also pretty much disappeared, and there is much less convection. I expect they will downgrade him tomorrow, so this is my last entry on 'King Arthur of the Nights of the Round Storms'.

I'll be back when we have another one out there. I hope everyone had a safe and fun day! :-)

Toodle pip!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
-------------------------------
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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