Weather Nerd

"Joker" still not a T.D. -- yet

Invest 92L, a.k.a. the Joker, a.k.a. proto-Fay, still isn’t a tropical depression quite yet, according to the National Hurricane Center’s “Special Tropical Disturbance Statement” at 5pm EDT:

DATA FROM NOAA AND AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT… ALONG WITH SURFACE OBSERVATIONS AND SATELLITE IMAGERY…INDICATE THAT THE LOW PRESSURE AREA LOCATED OVER THE VIRGIN ISLANDS HAS NOT DEVELOPED INTO A TROPICAL DEPRESSION. HOWEVER…UPPER-LEVEL WINDS ARE BECOMING MORE FAVORABLE FOR DEVELOPMENT…AND A TROPICAL DEPRESSION COULD FORM AT ANY TIME DURING THE NEXT DAY OR TWO AS THE SYSTEM MOVES WEST-NORTHWESTWARD ABOUT 15 MPH.

This is a script we’ve seen play out several times this hurricane season: a tropical wave seems to have everything going for it, atmospherically speaking, and the NHC keeps saying it could imminently become a tropical depression or storm — but, for some reason, the wave has trouble getting its act together. Weatherbloggers are on the edges of their seats for days, obsessing over an as-yet nonexistent tropical cyclone. Development remains “imminent” hour after hour, recon mission after recon mission. Yet nothing happens.

But I don’t think 92L will dither much longer. The low-level circulation center and the mid-level circulation center are still sort of battling it out, and there isn’t yet a fully closed circulation at the surface, but it really does seem like this thing’s on the brink. I’d be surprised if T.D. 6 isn’t designated by the time I go to bed tonight. I’ll also be surprised if it isn’t Tropical Storm Fay by this time tomorrow, if not sooner. Dr. Jeff Masters agrees; he gives 92L “a high (>80% chance) of becoming a tropical storm by Friday afternoon.” He also writes:

The long range track of 92L is highly uncertain. Take your pick of 8 am EDT model runs:

GFDL, HWRF: parallel to the east coast of Florida, 50-100 miles offshore
UKMET: Through South Florida into the Gulf of Mexico
NOGAPS: Through the Florida Keys, then northwest towards the Alabama/Mississippi coast
GFS: Through the Bahamas, then north towards North Carolina
Canadian: Across Cuba and through the Cayman Islands, then north in the Gulf of Mexico

Heh. It’ll be interesting to see what the 8pm EDT model runs do, since they’ll have data from this afternoon’s reconnaissance missions.