TS Ana and TS Bill: August 15 Update A

Oh codswallop AND Great Googlimoogies!!! I am sans internet for 36 hours,
and what happens? We have not one, but TWO systems out there. If only
there was some sort of hand-held device that allowed internet access from
pretty much anywhere at any time...

Hmmm. So, TS Ana and TS Bill. I believe those in the VIs/St. Thomas are
getting ready as the forecast currently calls for these storms to pass
that area as possible hurricanes.

TS Ana:
Currently centered at about 14.4N, 50W, she's moving westward quite
quickly at 17 mph. There isn't much convection at the moment and what is
present is all to the east of the circulation because there is sufficient
wind shear. There is also quite a lot of dry air surrounding this storm.
The wind shear and dry air will keep this storm in check for some time.
However, it looks like wind shear will die down a bit, and as she moves
west she moves over warmer waters and is already over sea surface temps of
28-29 deg C.

The circulation is good in the lower atmosphere, but has not yet reached
higher altitudes. This is a good thing - it means she's still a weak
system as we can also see from her wind speeds which are about 40mph (TS
range: 39-73mph, 34-63kt). Central pressure 1005 mb.

The track: Yeah, I think you guys in the northern Caribbean should be
prepared just in case - it looks like it will pass close to you. There's a
ridge of high pressure that Ana is following westward/WNW. It extends
across the VIs, passes just south of PR, and south of Hispaniola. They
just moved that track forecast a little to the south in response to models
(which are responding to the pressure fields). If that field shifts
marginally southward, she'll pass you to the south. Too soon for me to
tell.

TS Bill:
Bill is bigger than Ana. From satellites, it looks like he's centered at
about 11.3 N, 35.2W and is moving west at 16mph (speed from the NHC). This
system has more water vapor surrounding the center of circulation, and is
also over water temperatures of 28-29 deg C. Both factors are conducive to
helping the system grow a bit. Central pressure: 1004 mb, and wind speeds
are near 40mph, so he's still weak.

There is some circulation throughout the entire troposphere (lowest part
of atmosphere), but it is not yet very well defined (it's er... blob
shaped instead of circle shaped :)). But that there is some vorticity also
indicates that this could be a better formed storm. As with Ana, it looks
like wind shear will decrease in his path.

The track: With a storm so closely following behind another storm, the
path is usually very similar. The reason for this is because they follow
the same pressure lines, and although the pressure fields change a bit
from day to day, they don't change that much. We've seen this in the past
with various storms, the most famous recent examples are Katrina and Rita
in 2005, and Frances and Jeanne in 2004.

For the track, the pressure fields are critical. For intensity, the track is
important.

That's it for now folks. I should have better internet access tomorrow
afternoon(ish).

Night night from this side of the Atlantic.
J.

Blog entries 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,
hypothetically, I was there and I was, hypothetically, going to "run away,
run away" (Monty Python), I'd let you know.
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