Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 3:37 PM GMT on August 19, 2007
Hurricane Dean continues to pound Haiti and the Dominican Republic with high winds and heavy rain, and is headed for a very close encounter with Jamaica and the Cayman Islands. Early this morning, winds at Barahona on the southernmost point of land of the Dominican Republic hit 52 mph, gusting to 104 mph. Sustained hurricane force winds are expected to remain well south of both Haiti and the Dominican Republic, but a major spiral band has brought extremely heavy rain to the south portion of both countries.
Figure 1. Microwave satellite image of Dean taken at 7:17am EDT Sunday August 19. Think of this as a weather radar in space--the red areas show where the most intense thunderstorms in the spiral bands and eyewall are occurring. Note the incomplete double ring of echoes around the dark blue eye. Dean has two eyewalls, concentric around each other.
Jamaica and the Cayman Islands
Jamaica is already receiving high winds and heavy rain from an outer spiral band. How bad will it get? The big question is if the eyewall will move over the island. Unfortunately for Jamaica, Dean has two eyewalls, forming concentric rings (Figure 1). The inner eyewall is 15 miles in diameter, and the outer eyewall is 37 miles in diameter. Winds of Category 3 and 4 strength are blowing in both eyewalls, as seen in the latest data from the SFMR surface winds taken by the Hurricane Hunters. So, Dean's center has to pass more than 25 miles south of Jamaica for the island to be spared the worst of the hurricane. The nation's capital, Kingston, lies on the southern portion of the island, and will be the hardest-hit major city. The tourist city of Montego Bay is on the northern part of Jamaica, and will fare much better.
The same story holds true for the Cayman Islands. Grand Cayman, the southernmost of the islands, it at greatest risk. If Dean passes more than 30 miles south of the island, they will miss seeing the outer eyewall of Dean and will fare relatively well. It's going to be a close call, but it appears that both Jamaica and the Cayman will miss seeing the eyewall of Dean.
Mexico and Texas
Mexico will not be so lucky, and will receive a double beating. Dean is expected to make landfall twice, once near the tourist havens of Cozumel, and then again south of the Texas border. Mexico has to hope that the steering currents will be kind and take Dean south of the most heavily populated regions of the Yucatan. Hurricane Emily of 2005 grazed the southern tip of Cozumel Island as a Category 4 hurricane with 135 mph winds, and Dean may follow a similar path. Mexicans can take heart in the fact that Emily caused no deaths in Mexico, and damage was surprisingly light. Most of the tourist regions were relatively unaffected by Emily--it was Wilma two months later that really punished the Mexican Riviera.
As for Texas, it looks right now like only extreme southern Texas near Brownsville needs to worry about Dean. Hurricane Emily hit 90 miles south of Brownsville as a Category 3 hurricane in 2005, and I expect a similar story will unfold for Dean. Emily brought sustained winds of about 40 mph to extreme south Texas, a 4-5 foot storm surge, eight tornadoes, and heavy rains. Damage was minor.
Links to follow:
Radar in Pilón, Cuba.
Radar from Guantanamo Bay, Cuba.
Morphed microwave animation.
Kingston, Jamaica observations.
Montego Bay, Jamaica observations.
Grand Cayman observations.
After Dean, what next?
There is an area of disturbed weather that has formed off the northeast coast of South America, 400 miles southest of Barbados. Wind shear is 20-25 knots in this region, and will stay too high to allow develoment for at least the next two days. None of the reliable computer models are suggesting anything will develop over the coming week. The ITCZ region between Africa and the Lesser Antilles is relatively quiet.
The remains of Tropical Storm Erin re-intensified this morning into a major storm that slammed central Oklahoma with rains up to seven inches and wind gusts of tropical storm strength. The radar presentation of Erin's remains (Figure 2) looks remarkable tropical storm-like. I've saved a long animation of this "landcane". Numerous flood watches, flood warnings, and severe thunderstorm warnings have been posted for Oklahoma today.
Figure 2. The remains of Tropical Storm Erin re-intensified into a remarkably tropical storm-like cyclone today.
Typhoon Sepat has moved inland over mainland China, after hitting as a Category 1 storm. Earlier, Sepat hit Taiwan as a Category 3 typhoon. No deaths occurred on Taiwan, but at least 15 died in China--11 of them in a tornado spawned by the typhoon.
I'll have a full update Monday morning, and may have a short update later today.
Comments will take a few seconds to appear.