31 August 2008

Gustav heading for Louisiana, Hanna heading for the Bahamas, TD9 ready to form...

Gustav underwent rapid intensification Friday evening through Saturday afternoon.  In 24 hours ending 00Z Sunday, the central pressure fell 34mb, and in 23mb in 12 hours.  It strengthened from a 60kt tropical storm to a 130kt CAT4 hurricane in 27 hours.  Unfortunately, it accomplished this while heading for, and passing over, western Cuba, causing extensive damage.

Since exiting Cuba, it has had a hard time reorganizing, though still a 100kt CAT3 hurricane.  It is heading NW at 15kts, toward the central LA coast, and landfall is expected Monday morning as a major hurricane near Marsh Island.  However, there is still uncertainty, and a hurricane warning covers the LA and MS coasts.  As far as Katrina-ravaged New Orleans goes, so far about 15,000 people have evacuated, and evacuation orders are still in place for the city.  Lake Pontchartrain can expect a 15-20 foot storm surge on Labor Day, which will certainly re-test the levee system protecting the below-sea-level city.  Other parishes in coastal LA also have mandatory evacuation orders.  As of this writing, over 3/4 of oil production in the Gulf has ceased, as platforms and rigs are evacuated and shut down for the duration of the storm.

The latest intensity is 100kts and 962mb.  It is forecast the strengthen a bit more again, perhaps to CAT4 status, before landfall.  It's currently looking ragged on satellite, lacking a clear eye, showing signs of southerly vertical shear, and has dry air wrapping around west and south of it.  The main factor in its favor is deep, warm water under it.

You will be able to track its progress toward the coast via radar loops that I'm generating... a long and short range from New Orleans, and a short-range from Lake Charles (all are available at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/atlantic/).

Hanna, still maintaining modest tropical storm intensity, is strongly sheared.  Latest intensity is 45kts and 999mb, and heading WNW at 9kts.  It's now a couple degrees north of the Turk islands, and it is expected to track slowly westward toward the Bahamas, then NW toward the southeast US coast as a hurricane.  Landfall could be sometime next weekend... however, the steering environment is incredibly complicated, and Hanna will just have to be watched for the next few days to figure out where it's going!

The easterly wave I mentioned 2 and 3 days ago near the Cape Verdes has gotten better organized and is now located near 16N 35W.  Development of this wave should be slow as it heads W at 12kts.  The next name on the list is Ike.

Please visit my tropical Atlantic headquarters.

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