TS Isaac: September 29, Update A

Welcome to my new two-step program.

Isaac is becoming a little better organized, and he has also started to
move in a more westward direction. The problem with this change in track
is two-fold:
1. It brings him a little closer to land (not so much of a problem really)
2. It keeps him over warm waters (of 26 deg C), which may mean that he
will intensify a bit more than expected.

The westward shift in direction is because high pressure has developed
in front of him (see blog entry: Hurricane Gordon & Hurricane Helene:
September 16, Update A for why this would cause a more westward
movement). At the moment the models are divided as to how long this
west-north west motion will continue. There are two reasons for the
division in opinion:
1. They are trying to predict how long this high to the north of Isaac
will persist
2. There is a low pressure front moving eastward from the US into the
Atlantic, and depending on Isaac's speed, this will interact with the
storm and help him turn toward the north and then north-east.

Here's an image of the low front (band of clouds extending from the
north-east to the south-west off the US coast) and the storm:
http://www.ssd.noaa.gov/goes/east/nwatl/vis-l.jpg

By the way, this is the same low front that brought those chilly
temperatures of 83F (28 degs C) to Florida yesterday. Brrr.

Wind speeds within the system are 45mph (TS: 34-73mph). He is currently
moving along at a fairly slow 6mph (another indication that he's bumping
into high pressure). There is still dry air around the system, but he is
entering an area of weaker wind shear. So, there is room for some
intensification - between the shear and the warm water. Plus, as his
speed is quite slow, he will be over that warm water for longer.

Have a nice day,
J.
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DISCLAIMER:
These remarks are just what I think/see regarding tropical storms (my
storm blog). If you are making an evacuation decision, please heed your
local emergency management and the National Hurricane Center's official
forecast. This is not an official forecast.
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