Significant change in forecast track for Tropical Storm Debby

Debby remains a tropical storm at 5pm EDT with maximum sustained winds of 60 mph, and continues to move northeast at 3 mph. Tropical storm-force winds (39 mph) extend 200 miles from the center of the storm. Tropical storm conditions are present or close to being present along the northeast Gulf coast. The biggest change in the 5pm update from the National Hurricane Center is the forecast track—see below for discussion on that. Most of the buoys in the northern Gulf are experiencing tropical storm strength winds. Weather stations in Florida have been recording anywhere from 2 to 6+ inches of rain today, and tornado watches have been posted this afternoon. There are nine tornado reports in southern Florida thus far today, one of which caused at least one fatality in Lake Placid. Tornado warnings will likely continue through the night. The National Hurricane Center describes Debby as "sprawling" this afternoon, with most of the thunderstorm activity well-removed from the center of the system. Debby's rainfall extends from Pensacola, Florida north to almost Macon, Georgia, and south and east to Fort Lauderdale, Florida. A hurricane hunter mission flew the storm earlier this afternoon and found no winds to support more than a tropical storm, but flight-level winds were relatively high at almost 90 mph. The next hurricane hunter mission is tentatively scheduled for Wind shear remains moderately strong (10-20 knots) to the north and east of the storm, and is not expected to change over the next couple of days. Debby continues to appear large but hindered by shear on satellite this afternoon. Most of the strong thunderstorm activity is relegated to the north and east, and the southwest portion of the storm remains bare, though not as bare as yesterday.


Figure 1. Sunday afternoon satellite image of Tropical Storm Debby in the Gulf of Mexico.


Figure 2. Track forecast from the National Hurricane Center for Tropical Storm Debby.

Forecast for Debby
Debby continues to drift northeast in defiance of what many of our trusted global forecast models have been suggesting over the past two or three days. The National Hurricane Center has responded to this by making a dramatic and warranted shift in their forecast track. This afternoon the center is calling for potential landfall on Thursday, likely somewhere in the Florida panhandle, though the forecast cone extends from the Mississippi/Alabama border to the Suwannee River in Florida. Models are actually starting to come into somewhat of an agreement now on the forecast track toward Florida. The GFS, UKMET, GFDL, and CMC are suggesting that Debby will continue to drift northeast and make landfall in the southeast panhandle of Florida. The HWRF is the only model that is still going for a west-to-Louisiana solution. The earlier run from the ECMWF backed off on it's Texas forecast, and is appears to becoming around to agreement with the GFS, which has been forecasting a track to the northeast for days, now. In terms of intensity, the Hurricane Center qualifies their forecast with the fact that Debby is going to spend plenty of time over water in the next couple of days, so strengthening is definitely a possibility. However, while sea surface temperature is warm, it will start to cool the longer Debby lingers, and the actual heat available in the northern Gulf is relatively low. Most of the models also suggest Debby will remain a tropical storm. Debby will continue to produce constant, heavy rain along the northeast and eastern Gulf coast over the next few days, and flood watches and warnings have been issued from Mobile, Alabama to southern Florida to reflect that.

Angela