Karen defeated; new disturbance a threat to the Gulf of Mexico

Wind shear put an end to Tropical Storm Karen yesterday. Karen's remains continue to generate a large area of disturbed weather a few hundred miles east of the northern Lesser Antilles Islands (Figure 1). This morning's QuikSCAT pass showed some rotation still exists near the surface, with winds up to 30 mph. Wind shear has fallen to 20 knots over Karen's remains, and some of the models forecast the shear will fall below 15 knots by Tuesday, which may allow redevelopment of the storm. Both the UKMET and NOGAPS model revive Karen later this week, and show it moving very slowly to the west towards the U.S., but well offshore. The GFS model keeps the shear high, and does not redevelop Karen.


Figure 1. This morning's visible satellite image.

Bahamas tropical disturbance
A potential significant threat area has developed today off the U.S. East Coast along an old frontal boundary. Several areas of heavy thunderstorm activity have started firing up along this old front. Wind shear is about 20 knots over the region today, so only slow development will occur. By Tuesday, the shear is forecast to drop below 15 knots, and most of the computer models are forecasting that a tropical depression will form near Florida or Cuba. This storm is forecast to move westward across the Gulf of Mexico, pushed by a strong ridge of high pressure expected to build in. An upper-level anticyclone aloft is expected to develop as well, providing an environment favorable for intensification. The UKMET model is forecasting a strong tropical storm or weak hurricane by Friday for the Texas/Mexico border region. The other models are not so aggressive, but all see the possibility of a tropical storm impacting the western Gulf of Mexico in Louisiana, Texas, or Mexico sometime Thursday through Saturday. The Hurricane Hunters are on call to fly into this system Tuesday afternoon, if necessary. Texas is at highest risk from this potential storm.

Melissa
Tropical Depression Melissa is not long for this world, thanks to wind shear of 15-20 knots that is expected to increase further as Melissa heads northwest. Melissa is not a threat to any land areas, and will not be around three days from now.

I'll have an update Monday.

Jeff Masters