Weather Nerd

Meet Tropical Depression Seven

The National Hurricane Center has initiated advisories on T.D. #7, as of 11:00 AM EDT. It is forecast to become Tropical Storm Gustav later today. It already looks rather Gustav-ish on satellite:

td7-sat1z.jpg
NOAA visible satellite at 10:15 AM EDT. Closeup here.

The NHC discussion notes that satellite images “SHOW A RELATIVELY CLEAR AREA NEAR THE CENTER THAT RESEMBLES AN EYE.” A reconnaissance aircraft will visit the system this afternoon, shortly after 2pm EDT, and it’s possible T.D. Seven will be upgraded to T.S. Gustav at that time. Indeed, it sounds like the NHC expects that to happen, given this language in the discussion:

OUR INITIAL INTENSITY ESTIMATE IS CONSERVATIVELY SET AT [35 MPH] BASED ON AN EARLIER REPORT FROM NOAA DATA BUOY 42059. OBSERVATIONS FROM AN UPCOMING AIR FORCE HURRICANE HUNTER MISSION SHOULD GIVE UPDATED INFORMATION ON THE STRENGTH OF THE SYSTEM.

Where will this soon-to-be-Gustav go? The official forecast track shows it crossing Haiti and paralleling the north coast of Cuba, implying a threat to Fay-soaked Florida in about a week. But the NHC says this forecast, particularly the latter part, is low-confidence, as it basically “splits the difference” between two divergent schools of thought among the computer models.

Bottom line, it’s just way too early to say where proto-Gustav will go. It could eventually threaten anyone from the Southeast U.S. to Belize and the southwestern Gulf Coast (i.e., central Mexico). Dr. Jeff Masters is worried about a “deja vu” scenario for Florida, while Alan Sullivan writes, “If this system gets through Yucatan Channel into the Gulf, it could be a troublemaker.”

Whatever its exact track, the storm has a decent shot at intensification in the short- and medium-term, according to Dr. Masters:

Sea surface temperatures and total oceanic heat content in the Central Caribbean are very high, and [T.D. 7] is in a environment very favorable for intensification. Wind shear is predicted to remain very low to moderate, 0-15 knots, for the next five days. An upper level high pressure system is currently sitting over central Cuba, and if [T.D. 7] can position itself under this high, it will provide very favorable upper-level outflow conditions for the storm later this week. The main restriction on [T.D. 7]’s development will, like for Fay, be interaction with land. The islands of Hispaniola and Cuba will provide formidable obstacles to intensification.

The official NHC forecast brings it to just shy of hurricane strength — 70 mph — in four days. That, too, may be “conservative.”