Bahamas disturbance 97L little threat; 98L worth keeping an eye on

A tropical wave a few hundred miles northeast of the Bahama Islands (Invest 97L) has a moderate amount of disorganized heavy thunderstorms, and is headed northwest at 10 mph. Satellite loops show that heavy showers from 97L are affecting portions of the Bahama Islands, and this activity will continue through Tuesday. Wind shear is a moderate 10 - 20 knots over 97L, the atmosphere is moist, and ocean temperatures are a very warm 29.5°C. With wind shear expected to remain in the moderate range through Tuesday night, some slow development is possible today and Tuesday. However, by Wednesday, 97L will turn to the north and then northeast, encountering high wind shear of 20 - 40 knots. This high shear should be able to destroy 97L. In their 8 am Tropical Weather Outlook, NHC gave 97L a 10% chance of becoming a tropical cyclone by Wednesday morning. Rains from 97L will not affect the U.S.


Figure 1. Morning satellite image of Invest 97L just northeast of the Bahamas. Image credit: NOAA.

98L midway between Africa and Lesser Antilles
A tropical wave midway between Africa and the Lesser Antilles Islands (Invest 98L) has a moderate amount of disorganized heavy thunderstorms, and is headed west to west-northwest at 15 - 20 mph. Wind shear is a moderate 10 - 20 knots over 98L, the atmosphere is moist, and ocean temperatures are a very warm 29°C. With wind shear expected to remain in the moderate range through Tuesday night, some slow development is likely until 98L encounters much higher wind shear of 20 - 40 knots Wednesday though Saturday. Moisture from 98L could arrive in the Lesser Antilles Islands as early as Thursday, though Friday is more likely. On Monday, the GFS model predicts that wind shear will fall low enough for 98L to develop into a tropical depression a few hundred miles northeast of Puerto Rico. The NOGAPS model shows some weak support for this idea, but the ECMWF model does not. In their 8 am Tropical Weather Outlook, NHC gave 98L a 10% chance of becoming a tropical cyclone by Wednesday morning.

Jeff Masters