According to NOAA’s National Data Buoy Center, the water temperature topped 87ºF (30.5ºC) on Thursday. Great for diving, but VERY conducive to serious storms. Here’s yesterday’s report from Dr. Jeff Masters on Invest 91L:
African wave 91L a potential threat to the Lesser Antilles
A well-organized African wave near 9°N 44°W (Invest 91L) is headed west-northwest at 15 – 20 mph, and could arrive in the vicinity of the Lesser Antilles Islands as early as Monday night. Residents of the Lesser Antilles should pay careful attention to this system, as it has the potential to organize into a tropical storm before reaching the islands. While visible satellite loops currently show only minimal heavy thunderstorm activity and no signs of a surface circulation, there is a pronounced large-scale rotation to the cloud pattern. Water vapor satellite loops show that a large area of dry air from Africa lies just to the north of 91L, and this dry air is inhibiting development. The SHIPS model is diagnosing low shear, 5 – 10 knots, over 91L, but the University of Wisconsin CIMSS analysis shows that moderate shear, 10 – 20 knots, is affecting 91L. Sea surface temperatures are 27.5° – 28°C, which is 1° above the 26.5°C threshold usually needed to support a tropical storm.
Forecast for 91L
Low to moderate wind shear of 5 – 15 knots is predicted along 91L’s path over the coming three days, which should allow the storm to steadily organize, assuming it can shut out any incursions of dry air that might intrude. The latest 06Z run of the GFS model does show 91L developing into a tropical storm by Monday, but the other three most reliable models for forecasting formation of a tropical storm–the ECMWF, NOGAPS, and UKMET models–show little or no development of 91L in their latest runs. On Monday, when most of the models predict that squalls of rain from 91L will begin affecting the Lesser Antilles, wind shear is expected to rise to the moderate or high range, which should act to interfere with development. The latest runs of the GFDL and HWRF models show 91L developing into a hurricane by Monday, but these models are not to be trusted for systems that have not developed into a tropical depression yet. The long-range path of 91L could take it through the Caribbean or towards the U.S. East Coast; it is too early to know with path might be more probable. NHC is giving a 30% chance that 91L will develop into a tropical depression by Sunday morning.
I am trying to take today off. We will see. If so, my major project of the day will be to get as fully packed as possible for my impending trip to the Mother Country (Texas) for the birth of my granddaughter, Josie.
Capt. Steve Willis
Aboard S/V Escape