Ernesto moves into the Florida Keys

The Hurricane Hunter reports from late this morning indicate that Ernesto's pressure remains steady at 1005 mb, and the maximum sustained surface winds steady at 45 mph. Ernesto's appearance on satellite imagery is much improved, with upper-level outflow being established to the north, and the size and depth of heavy thunderstorm activity increasing. Key West radar animations show an increase in organization and intensity of the spiral rain bands, and it won't be long before the Hurricane Hunters observe a falling pressure and rising winds. We are very lucky this storm does not have another day over water, or it would be near Category 2 hurricane status. Ernesto has only about 12 more hours over water, and should come ashore in the Everglades tonight with peak winds of 60 mph.

Marathon in the Keys had a heavy squall go through at 11:09am EDT, and reported a wind gust of 27 mph. Winds at the offshore buoy on Sombrero Key near Marathon were sustained at 35 mph, gusting to 40 mph at 11am this morning. Winds will continue to rise in the Keys this afternoon, and a 1-3 foot storm surge can be expected.

The latest forecast models are still in excellent agreement, calling for a landfall in the Everglades tonight, a long 2-day passage up the length of Florida, followed by a re-emergence into the Atlantic and possible re-intensification to a Category 1 hurricane before a second landfall in the Carolinas. Ernesto should then slowly push inland over the mid-Atlantic states, and may create inland flooding problems due to its slow movement northwards.


Figure 1. A tropical wave to watch, and one to ignore--visible satellite image from 9:45am EDT over the Atlantic.

New tropical wave to watch
A concentrated area of thunderstorms has developed about halfway between Africa and the Lesser Antilles Islands, near 9N 36W. This tropical wave is showing some rotation, and had winds up to 60 mph in some of the heavier thunderstorms, according to a 4:15 am EDT pass from the QuikSCAT satellite. The GFS model does develop this system into a tropical storm by Friday, and predicts it will be a threat to the Lesser Antilles Islands early next week. This wave is very similar in position and appearance to the wave that spawned Ernesto. Wind shear is about 10-15 knots over the wave, which is low enough to allow some slow development. Sea Surface Temperatures are 84-86F (29-30 C), which is very favorable for development. However, the intensity of the heavy thunderstorm activity has declined markedly this morning, and the wave is not a threat to develop until Thursday at the earliest. A large spiral of low clouds to the wave's north-northwest is associated with another tropical wave. This wave we can ignore, since it is embedded in a large area of African dust that should inhibit development. The computer models are very bullish in developing waves coming off the coast of Africa in the next two weeks, and I expect we'll have at least two new named storms by the time the peak of hurricane season arrives, September 10.

I'll be back with an update by 4:30 pm EDT today, and include some thoughts on the anniversary of Katrina.

Jeff Masters