[StBernard] Tropical outlook for G.O.M.

[Westley Annis]

>From Wx underground:


an area of disturbed weather has developed off the east coast of Florida, in
association with a tropical wave interacting with a trough of low pressure.
This disturbance has been labeled "93L"
<http://www.wunderground.com/tropical/tracking/at200793_model.html>  by NHC
this afternoon. Animations of long-range radar out of Melbourne, Florida
<http://www.wunderground.com/radar/radblast.asp?zoommode=pan&prevzoom=zoom&n
um=6&frame=0&delay=15&scale=1.000&noclutter=0&ID=MLB&type=N0Z&showstorms=0&l
at=0&lon=0&label=you&map.x=400&map.y=240&scale=1.000&centerx=400&centery=240
&showlabels=1&rainsnow=0&lightning=0&lerror=20&num_stns_min=2&num_stns_max=9
999&avg_off=9999>  and satellite loops
<http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html>  show that
thunderstorm activity off the Florida coast is increasing, but remains
disorganized. Wind shear
<http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8shr.html>
over the disturbance has fallen from 30 knots to 20 knots today, and is
expected to fall below 10 knots by Thursday. The disturbance is moving
westward, and will bring heavy rain to Florida and the Bahamas today through
Thursday.

The four reliable computer models for forecasting tropical cyclone genesis
all predict that once this area of disturbed weather crosses Florida and
emerges into the eastern Gulf of Mexico on Thursday, wind shear will drop
enough to allow a tropical depression to form. The path such a storm might
take is highly uncertain, and the models have diverged significantly since
yesterday's runs. A strong ridge of high pressure is setting up over the
eastern half of the U.S., and is expected to remain anchored in place for at
least ten days. This is the type of steering pattern we experienced during
the Hurricane Season of 2005, and favors westward-moving storms. This ridge
will act to steer any developing storm in the Gulf of Mexico towards the
west, to the Texas coast, or even west-southwest, to the northeastern
mainland Mexico. However, this steering pattern will be complicated by the
presence of an upper-level low pressure system over the Gulf of Mexico. This
upper-level low is currently forming over northern Florida, and is expected
to drift southwestward or westward over the Gulf later this week, and
gradually weaken. Depending on the strength and movement of this low, a
storm that forms in the eastern Gulf could be steered anywhere from the
Florida Panhandle to northeastern Mexico. One model, the NOGAPS, predicts
that the storm will move west-southwest into the Bay of Campeche
(southwestern Gulf of Mexico), and stall out for many days. The UKMET, GFS,
and ECMFW models foresee that the storm will make landfall in Texas or
Louisiana Sunday or Monday. The intensity such a storm may reach is also
highly uncertain. The NOGAPS model predicts 93L will eventually dissipate
over the southwestern Gulf, while the SHIPS intensity model brings 93L to
Category 1 hurricane strength by Saturday. All residents along the Gulf of
Mexico coast need to consider what actions they might need to take if a
hurricane develops in the Gulf this weekend. The highest danger region is
from New Orleans westward to Brownsville, Texas. A hurricane hunter airplane
is on call for Thursday afternoon.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=795&tstam
p=200709