Eye of the Storm

backup for http://radio.weblogs.com/0131089/

Thursday, August 25, 2005

At 11 AM EDT, the center of Tropical Storm Katrina was at 26.2 North 79.3 West, 55 miles east of Fort Lauderdale Florida and moving to the west at 6 mph with a further decrease in forward speed expected. On this course, Katrina will cross the coast tonight or early Friday morning. Maximum sustained winds are 60 mph and minimum central pressure is 997 millibars (29.44") (now 990, see discussion)

Tropical Storm Katrina Advisory Number Eight

Katrina is looking stronger on satellite and radar. Doppler radar has recorded some hurricane force winds at 10.000 feeton occasion, but the averages over a one mile square have been equivalent to 55 mph at the surface. The intensity estimate was a blend of the afforementioned doppler radar observations and estimates from satellite imagery. A recon plane with Stepped Frequency Microwave Radiometer capability is now in the storm and a recent report shows that pressure has dropped to 990 millibars, yet that pressure drop has yet to equate to an increase in wind speeds.

Upper-air data indicates that the upper-level ridge to the north of Katrina is shifting to the east, creating a steering current that would guide Katrina west. Models are in good agreement through 48 hours, but are split thereafter, with the UKMET being the furthest east (bringing the storm across northeast Florida with only a brief amount of time over the Gulf of Mexico) and the GFDL being furthest west (it takes the storm to Fort Walton Beach or so with a significant amount of time over water). The official forecast is an average of the NHC model guidance. Forecaster notes that the GFDL has been consistent in showing a southwest course across the peninsula of Florida, but he thinks that while the track is possible, it is an exxageration.

Dry air continues to affect Katrina, thereby keeping her intensity in check. Radar indicates that thunderstorms are now popping up in areas that were formerly dry. Given her slow forward speed and the fact that she is yet to cross the Gulf Stream, Katrina can still become a category one hurricane before landfall. Restrenghtening is expected after Katrina crosses into the Gulf of Mexico (second landfall is also forecast to be as a category one hurricane).

Tropical Storm Katrina Discussion Number Eight

Official forecast track

The eye of Katrina is now on Miami's short range radar.

The output of the global forecast models (with the upper-air data from NOAA's Gulfstream-IV jet) showed that my area of concern for the second landfall (Pensacola to St Mark's) is for the most part too far west. Accordingly, I'll adjust it to run from Panama City Beach to Yankeetown. The closer in to the coast of the peninsula that Katrina goes, the weaker she will be due to the shallow waters. A track along the GFDL forecast would put her over deeper water (with favorable warm temperatures extending most of the way down), thereby enabling the storm to become significantly stronger. Regardless of the exact track, it is clear that it will be a rainy few days for almost all of the Sunshine state.

For south Florida, the most significant problem will be the rain. Rain totals could run as high as a foot or greater in some areas due to how slow Katrina will be moving as she crosses the peninsula.


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