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 , 3:49 AM GMT on December 11, 2007
The hurricane season of 2007 is definitely not over! Subtropical Storm Olga is the 17th December named storm to develop in the Atlantic since record keeping began in 1851. Seven of these 17 storms have occurred since 1995.
As seen on visible satellite loops, the heavy thunderstorm activity that was displaced 100-300 miles to the north of the center has now wrapped closer to the center of Olga's circulation. This is the sign of a system evolving to be a tropical storm. However, an upper level low pressure system over the Virgin Islands is dumping some cold air into the storm, and Olga is still technically a subtropical storm. The difference is not important, as the winds and rain are similar for both types of storms. Long range radar out of Puerto Rico clearly shows the circulation of Olga and some steadily organizing bands of rain. Rain is the major threat from Olga, and amounts of 3-4 inches have already fallen over northern Puerto Rico, and a Flood Watch has been posted for much of the island. Heavier rain amounts of over six inches have fallen on ocean areas to the north of Puerto Rico (Figure 1), and rainfall amounts of up to 10 inches may hit the regions of the Dominican Republic hard hit by Tropical Storm Noel just six week ago. Haiti is also at risk of heavy rains that might cause life-threatening flash floods and mud slides.
Figure 1. Latest precipitation estimate from the Puerto Rico radar.
Wind shear, which dropped to about 15-20 knots this evening, is low enough to allow some slow strengthening Tuesday. By Wednesday, rising wind shear, plus passage over the rough terrain of Hispaniola, should be enough to tear Olga apart. The remnants of Olga may still bring heavy rains of 2-4 inches to Jamaica and eastern Cuba Wednesday and Thursday. None of the computer models foresee that Olga will survive to become a tropical storm in the Western Caribbean. The Hurricane Hunters are not on call to fly Olga.
I'll have a update Tuesday morning by 11am EST.
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