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A quiet Sunday in the tropics

By: Dr. Jeff Masters, 3:10 PM GMT on June 25, 2006

The tropics are quieter today, with the three systems we discussed yesterday all looking less interesting.

Firstly, the low pressure system we've been watching all week over the Bahamas is now just off the coast of central Florida. The low is now tracking north-northwestward, parallel to the coast, and should reach Georgia/South Carolina on Monday. The counter-clockwise spin of the low has sucked in dry air into its center, putting a damper on any development for today. It is possible on Monday that the dry air may dilute enough to allow some development to occur. However, this is unlikely if the center of the low--which is right on the coast--moves inland.

Figure 1. Preliminary model tracks for the Florida low.

Low 550 miles east of Bermuda
A second area to watch is a well-defined area of low pressure far out in the Atlantic at 35N 54W, about 550 miles east-northeast of Bermuda. The deep thunderstorm activity surrounding the low has diminished since yesterday, thanks to an increase in wind shear. Sea surface temperatures (SSTs) are in the 23-25 C range, which is below the 26 C threshhold usually needed for tropical storm formation. This low reminds me of the "Greek" storms Delta, Epsilon, and Zeta that formed in a similar location with similar SSTs last Fall. Today's storm may be able to spend enough time the next few days over waters just warm enough to allow it to make the transition to a subtropical storm and perhaps even a tropical storm. More probably, it will not develop. The SSTs are probably too cold and there is too much wind shear around. The system is not a threat to land right now, and will track westward at 10 - 15 mph towards Bermuda over the next few days. None of the computer models are forecasting this low to develop into a tropical storm.

Forecasted development north of Puerto Rico
Most of the global computer forecast models have been consistently forecasting a tropical or non-tropical storm to form northeast of Puerto Rico on Tuesday or Wednesday. Today is the fourth day in a row the models been making this forecast, but the model runs the past two days have been decidedly less bullish about developing such a system. I remain dubious that storm will develop in this region, since there is a lot of wind shear in the vicinity. If a storm does form here, it is forecast to move northward towards Bermuda or northwestward toward the Southeast U.S. coast. SSTs are in the 26 - 28 C range in the area, which is warm enough to support a tropical storm.

I'll be back with up update on Monday.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.