Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 10:19 PM GMT on October 18, 2005
Wilma's rapid intensification phase continues, with another 9 mb drop in the past 1 1/2 hours, for a total of 16 mb in the past three hours. The 7:09 EDT hurricane hunter report found a pressure of 954 mb, and maximum flight level winds at 5000 feet of 101 knots (116 mph). Wilma is a solid Category 2 hurricane, and probably on her way to Category 3 status by early Wednesday morning. The Hurricane Hunters don't fly in Category 2 and stronger hurricanes at 5000 feet altitude very often; I wonder if the next eye penetration will be done at 10,000 feet.
Wilma has claimed her first victims; up to ten are dead on Haiti in landslides triggered by the hurricane's heavy rains. Mudslides and flooding are also serious problems in the southeastern Cuban provinces of Guantánamo, Santiago de Cuba and Granma. Nearly 13 inches (33 cm) of rain was measured at Santiago de Cuba since Wilma's rains began. The Cuban newspaper Granma is reporting 255 homes damaged or destroyed in that town, and sections of the Sevilla-Guamá-Santiago de Cuba highway impassable due to swollen rivers, while landslides have blocked the Cordovelo-Loma Blanca road. In Jamaica, widespread flooding has cut off several communities and caused millions in damage to roads. All schools are closed on the island through Thursday and hospitals are taking only emergency patients. Rainfall rates as high as two inches per hour have been observed in the Blue Mountains of south-central Jamaica this afternoon.
Wilma's eye diameter is now a very tiny 8 nm (9 miles), up one mile since last report, but still very small for a hurricane. It will be interesting to see how long Wilma can maintain an eye that small; I expect the eyewall will collapse by morning and an eyewall replacement cycle will begin, with Wilma leveling out at Category 3 strength. The eye is now very prominent on satellite imagery, and spiral banding and upper-level outflow continue to improve and cover a larger area.
The remainer of my 5pm discussion appears below, unchanged.
Wilma became a hurricane today, tying the record of 12 hurricanes in a season set in 1969. In that year, the last two hurricanes formed after October 30, so 2005 has a decent chance of breaking that record. I expect 2005 will also break the record of 21 total storms, which it now shares with the 1933 hurricane season.
The upper level environment looks excellent but not perfect for intensification, with low wind shear and two good outflow channels, one on the north side, and one on the southwest side. About five knots of wind shear is degrading the outflow pattern and symmetry on the northwest side, and there is still some dry air there for Wilma to contend with. Continued intensification into a Category 3 hurricane by Wednesday looks reasonable, and I'd give it a 40% chance Wilma makes it to Category 4 status by Friday. The GFDL is calling for a 922 mb Category 4 storm by Friday, but this forecast is probably overdone, as the GFDL has been consistently too aggressive with its intensity forecasts for Wilma. By Saturday, Wilma will be far enough north that wind shear from an upper-level trough of low pressure will reduce Wilma's winds by perhaps 20 mph.
Wilma is currently traversing an area of high oceanic heat content (see Figure 1), and this heat content will not significantly fall unless Wilma passes north of the Florida Keys. I would expect an additional 10 mph reduction in Wilma's winds if she makes landfall in Florida north of the Keys, due to the lower heat content of the water. So, expect landfall as a strong Category 2 hurricane if Wilma moves through the Keys, or as a weak Category 2 hurricane further north. Remember that hurricane intensity forecasts are poor, especially 3 - 5 days out, so Wilma's intensity could easily be a full Category higher or lower than this.
Figure 1. Total heat content of the ocean is high over the northwest Caribbean and the southern Gulf of Mexico south of 25 N latitude. Images credit: NOAA/AOML.
Jamaica continues to take a pounding from Wilma, but this should end tomorrow night as Wilma pulls away. The next area of concern is northern Honduras and Nicaragua, where rains of up to 12 inches are expected. However, the portions of these countries that will receive the heaviest rains are relatively flat, so I do not expect massive loss of life from flooding in the mountains.
Next on Wilma's list will be the Cayman Islands, but flooding is generally not life-threatening in that nation. Mexico and Cuba may escape serious damage if Wilma passes through the Yucatan Channel as forecast.
Figures 1. Computer model forecasts for Wilma.
Wilma started moving WNW at 8 mph today, as all the computer models predicted she would. The models are pretty unified, bringing Wilma through the Yucatan Channel or across the western tip of Cuba, and then northeastward into the Florida Keys or the west coast of Florida by the weekend. Two models (the UKMET and GFS) predict that Wilma will pass just south of the Keys. The furthest north model is the Canadian, which picks Sarasota for its landfall. The GFDL, NOGAPS, and the official NHC forecast are in the middle, with a landfall over the Everglades of Southwest Florida. The NOAA jet is scheduled to makes its first flight tonight, and tomorrow morning we should have a better idea of which part of Florida is at most risk. Climatology favors a more southern track, and I expect that we'll see the models converge on a more southerly track through the Keys in the runs we see Wednesday morning.
Elsewhere in the tropics, there is a large area of disturbed weather midway between Africa and the Leeward Islands. Upper level winds are not favorable for development of this area, which is also too close to the Equator. I'll be back with a update in the morning.
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