After making forecasters and weather geeks wait for several days, Invest 93L strengthened enough on Wednesday to be named Tropical Storm Bertha by the National Hurricane Center Wednesday night. NHC forecasters made the move after analyzing data gathered by U.S. Air Force Reserve aircraft during afternoon and evening flights.
The Hurricane Hunters found top sustained winds of about 45 miles an hour. The barometric pressure was 1008 millibars. 1000 millibars is a good rule of thumb for measuring how well-organized a storm might be. Bertha's 11 p.m. Atlantic Standard Time position was about 275 miles east-southeast of Barbados. Bertha was racing along at west-northwest at 20 miles an hour. Tropical storm warnings are posted in Barbados, Dominica and St.Lucia. Tropical storm watches are posted in Puerto Rico, Vieques, Culebra and the U.S. Virgin Islands.
As far as the next two or three days are concerned, NHC forecaster Stacy Stewart says in his forecast discussion that Bertha is probably going to stay on the same course for the time being. “The NHC model guidance is in excellent agreement on the cyclone maintaining a general west-northwestward motion for the next 48 hours or so, followed by a gradual turn toward the northwest after that through 96 hours. By Day 5, Bertha is expected to turn northward as it moves around the western portion of the ridge.”
If Bertha follows the track projected by the NHC, it will cross the island of Hispaniola before swinging through the Bahamas and a course parallel to the U.S. Eastern Seaboard. Stewart describes conditions around Bertha as “not particularly favorable” for development over the next few days. However, that may be small consolation to people in the impoverished nation of Haiti where even heavy rainstorms can bring disastrous flooding. At the moment, that appears to be the worst threat from Bertha to any land mass, however, projected courses can change on short notice and storms can gain strength unexpectedly, so as with any storm it's a good idea for residents along the eastern parts of Florida and the rest of the U.S. Atlantic coastline to keep an eye on Bertha.