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.
More on these later.
J.
Blogs archived at: http://www.jyotikastorms.blogspot.com/
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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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