Monday, July 14, 2008

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/
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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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