Ex-TD 7 reawakening; Gordon Azores-bound; 94L may be a long-range threat
Satellite loops show that a small area of disturbed weather with an increasing amount of heavy thunderstorms has developed in southern Gulf of Mexico's Bay of Campeche, in association with the remnants of Tropical Depression Seven. Heavy rains from ex-TD-7 are beginning to impact the coast of Mexico between Tampico and Veracruz, and radar from Mexico shows some rotation to the echoes, but little in the way of spiral banding. With wind shear a light 5 -10 knots and very warm ocean waters of 30°C to take advantage of, ex-TD-7 has a 70% chance of becoming a tropical cyclone before it makes landfall over the Mexican coast on Saturday, said NHC in their 8 am EDT Tropical Weather Outlook. A hurricane hunter aircraft will investigate ex-TD-7 this afternoon around 2 pm EDT. Ex-TD-7's west-northwest to northwest motion should continue through landfall, and the storm may be capable of bringing heavy rains of 3 - 6 inches to the Mexican coast near Tampico. Brownsville, Texas should stay just north of the heavy rain area of ex-TD-7.
Figure 1. Morning satellite image of ex-TD 7.
Tropical Storm Gordon heads toward the Azores
Tropical Storm Gordon continues eastwards towards the Azores, and is not a threat to any other land areas. Satellite loops show Gordon has a respectable amount of organization and heavy thunderstorm activity. Gordon's environment has gotten marginal for a hurricane--wind shear is moderate, 10 - 20 knots, and ocean temperatures are near 26.5°C, which is right at the border of where hurricanes can usually exist. Water vapor satellite loops show a large region of dry air on the south side of the storm. The 8 am EDT run of the SHIPS model predicts that wind shear will remain moderate through Saturday night, then rise steeply to 30 - 40 knots on Sunday. At the same time, ocean temperatures will drop to 25°C. By Sunday, the combined effects of high wind shear, dry air, and cooler waters will likely act to weaken Gordon and make it no longer tropical. However, Gordon will probably still be strong enough Sunday night to potentially bring damaging winds and heavy rain to the Azores Islands. The extratropical remnants of Gordon will not bring any strong winds or significant rain to Europe.
Figure 2. Tropical Storm Gordon as seen by NASA's Terra satellite at 10:25 am EDT August 16, 2012. At the time, Gordon was strengthening, with 50 mph top winds. Image credit: NASA.
94L developing off the coast of Africa
A large tropical wave emerged from the coast of Africa Thursday night, and was designated Invest 94L by NHC this Friday morning. The models have been very gung-ho on this system, and develop it into a tropical storm by the middle of next week. 94L will follow a west to west-northwest track over the next week, and may threaten the northern Lesser Antilles Islands as early as Friday, August 24. This storm could eventually affect Bermuda, the U.S. East Coast, or Canada 10 - 14 days from now, but could also recurve harmlessly out to sea well before reaching the Lesser Antilles, as suggested by the 00 UTC run of the GFS model. In their 8 am EDT Tropical Weather Outlook, NHC gave 94L a 10% chance of developing into a tropical depression by Sunday morning.
Figure 3. MODIS satellite image of Invest 94L taken at 8 am EDT August 17, 2012, off the coast of Africa. Image credit: NASA.
I'll have a new post this afternoon.