Tuesday, July 21, 2009

Caribbean Blobette: July 21 Update A

Our 'little' blobette is in the Caribbean at about 66W, 17N, south of
Puerto Rico and the VIs. And it's growing.

In my humble opinion (that, as you know, I very reluctantly share from
time to time ;)) I think the NHC should upgrade this one to a higher
percentage of forming. The circulation has improved since yesterday, and
as soon as it got into the Caribbean the convection blossomed. The NHC
currently give it less than 30% chance of developing into a Tropical
Cyclone in the next 48 hours.

Water temperatures are a balmy 29 deg C and there is a lot of water
vapor in the atmosphere surrounding this system. Wind shear is still
high, at 30-40 knots, which is the primary reason why it's still
struggling to develop (although if you live in the PR and VIs, you might
disagree with this 'struggling to develop' malarkey later today).
According to the NHC, this blobette is moving W-NW at 15-20 mph which
seems a fair assessment.

Someone mentioned the Saharan Air Layer (SAL) yesterday as a reason why
the storm is inhibited... this is a layer of air (you could have guessed
that much, right?) which carries dust that comes off Africa (I'll let
you guess what part of Africa) and crosses the Atlantic. In some years
it can reach the Caribbean/eastern US and has been linked to increases
in health problems (such as asthma) amongst other things. Some friends
of mine are working on looking at the buggies (technical term ;)) that
are carried across on the grains of sand. Any Hollywood producers
reading this? I have a scary story idea ....

From satellite images, at the moment the SAL is not as strong (dense)
as it can get and it only extends from Africa to part way across the
Atlantic (about 50W), so this system is not being impacted by the SAL.
Storms and the SAL is an active area of research.

Have you guys in the VIs/PR got your brollies and wellie-boots ready? It
look like you might be in for some stormy weather today.

More later!

p.s.... those who are wondering about the very large convective area in
the middle of the Atlantic at about 45W, 5N, that isn't mentioned on the
NHC page... it's not got any circulation. Compared to the blobette in
the Caribbean and the smaller blob over the bahamas (that I'll mention
if it looks like anything is going on), the one in the Atlantic is
relatively minor.

Blog entries archived at: http://www.jyotikastorms.blogspot.com/

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.

No comments: