Fay's rains and tornadoes continue; disturbance 94L entering Lesser Antilles today

By: Dr. Jeff Masters , 2:18 PM GMT on August 23, 2008

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Tropical Storm Fay continues its trek over the Florida Panhandle, and it now centered over land just north of Apalachicola, after making its record 4th landfall on the state this morning. Radar and satellite loops show no major changes to Fay. The storm still has a large circulation with plenty of rain bands sprawling over much of northern Florida and southern Georgia. The center of Fay should emerge over the Gulf of Mexico just west of Panama City this afternoon, and we can expect a modest increase in strength as it feeds off the warm Gulf waters. Yesterday, Fay intensified from 45 mph to 50 mph when its center emerged over the water for 12 or so hours, and I expect a 5-15 mph increase in the winds by Sunday evening, before the center moves back over land again.

Fay's rains
Fay's rains continue to pile up over northern Florida, but have mostly ended over the Melbourne region, which endured it's greatest single-storm rainfall on record. Fay dumped an official 22.83" of rain on Cape Canaveral. According to the latest public information statement from the NWS office in Melbourne, we have an unofficial public observation at Melbourne/Windover Farms (through 6 am 8/22/08) of 26.65". The previous rainfall record for a tropical cyclone in the region was set in 1950, when Hurricane King dumped 15.44" of rain on Patrick Air Force Base near Cape Canaveral. Hurricane Wilma of 2005 holds third place--it dumped 13.26" on Kennedy Space Center.

Several locations around Cape Canaveral reported rainfall amount in excess of 20 inches, including four personal weather stations that send data to the Weather Underground:

Satellite Beach: 23.02"
@The-Beach, Cocoa Beach: 22.10"
LongWood, Melbourne: 21.44"
Jericho Backyard, Palm Bay:20.93"

Rainfall amounts in the Jacksonville region have alse exceeded 20 inches in some spots, according to radar estimates. On the plus side, Fay's rains have now increased the level of Lake Okeechobee by 1.6 feet. The lake level now stands at 12.83 feet, which is still about 2 feet below normal.


Figure 1. One of Fay's tornadoes touched down on Friday, August 22, at 6:25 pm EDT, at 3000 Camp Posalie Road near Kissimmee, in Polk County. The tornado damaged four mobile homes and a bridge. Image credit: Polk County Sheriff's office.

Fay's tornadoes
Fay has produced a total of 15 tornadoes so far: 4 on Monday, 5 on Tuesday, and 6 on Friday. More tornadoes are possible over the next three days. Figure 1 shows a tornado photo kindly forwarded to me by Bryan Farrow, a freelance news photographer in Florida. The tornado touched down yesterday in Polk County, damaging four homes and a bridge. NOAA's Storm Prediction Center has tornado reports, and we've also added tornado reports to our interactive Wundermap. It's essentially a clone of our Tornado page, showing current tornado warnings, storm reports, and past tornadoes back to the 1950s. It also shows radar loops (when available) and photos from WunderPhotos of the storm, damage, etc.

Links to follow
Wundermap for Central Florida
Tallahassee, FL radar

Disturbance 94L approaching the Lesser Antilles
Heavy thunderstorms associated with a tropical wave (94L) near 11N, 57W, about 200 miles east of the Lesser Antilles Islands, have steadily grown more concentrated over the past day. This morning's QuikSCAT pass showed no closed circulation, but did show a pronounced wind shift associated with the disturbance. Top sustained winds were about 30 mph. Visible satellite loops show no evidence of rotation, and the area covered by heavy thunderstorms is relatively modest. The storm has moistened its environment considerably, and dry air should be less and less of a problem for the storm over the next few days. Wind shear has fallen to a modest 10 knots over 94L and is expected to remain in the low range, 5-10 knots, for the next four days. NHC is giving this system a medium (20%-50% chance) of developing into a tropical depression by Monday morning.

The forecast for 94L
The GFDL model, which with yesterday's run was developing 94L into a powerful hurricane that threatens Jamaica, is no longer developing the storm. The ECMWF, NOGAPS, and Canadian model all develop 94L. They foresee the system will enter the eastern Caribbean Sunday, jog northwest and affect the Dominican Republic on Tuesday, then develop into a tropical depression by Thursday near the Dominican Republic or eastern Bahama Islands. The wind shear forecast for the Caribbean calls for very low values of wind shear below 5 knots for most of the coming week (Figure 2). Residents of the Lesser Antilles can expect heavy rain and 40 mph wind gusts from 94L when it blows through Saturday night through Sunday. Residents of the Dominican Republic, Haiti, and Jamaica should keep a careful eye on this potentially dangerous disturbance.


Figure 2. Wind shear forecast for the Atlantic for 2 am EDT Monday August 25 2008, as predicted by this morning's 2 am EDT run of the GFS model. Very low values of winds shear (red colors) are predicted for the entire Caribbean and Gulf of Mexico. Winds shear values less than 8 m/s (approximately 16 knots, the three red colors) are conducive for troical storm formation.

Disturbance 95L in the middle Atlantic
Another tropical wave (95L), near 19N 41W, halfway between Africa and the Lesser Antilles Islands, remains disorganized. Last night's QuikSCAT pass showed only a slight wind shift associated with 95L, and no closed circulation. Top winds were about 30 mph. Wind shear is a modest 10 knots over 95L, and is forecast to remain near 10 knots for the next five days. Visible satellite loops show only a small amount of heavy thunderstorm activity, and 95L is battling a large amount of dry air that surrounds the storm and is interfering with development. It will be several days before the storm can moisten it environment enough to potentially permit development, and NHC has downgraded 95L's chance of developing into a tropical depression in the next two days to low (<20% chance).

My next blog will be Sunday, or later today, if there's some significant development to report.

Jeff Masters

Tropical Storm Fay Flooding Deland, FL (Howmiester)
Downtown Deland, FL near the hardware store... 15.40 inches of rain in 4 days. Alot of flooding in the area from Tropical Storm Fay
Tropical Storm Fay Flooding Deland, FL

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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