200AM Eastern: There have been some shifts in the models tonight. Will have to wait until 500 AM advisory to see how the NHC responds. Don't be surprised if the track shifts east. As I've been saying for the last few days, everyone from Brownsville TX to Tampa FL needs to watch this system.
1222AM: I put in a short update at the bottom of the diary to account for the NHC's 1100PM advisory.
A Hurricane Hunter aircraft flew into a disturbance in the central Gulf of Mexico this afternoon and determined that the winds are strong enough and there's enough of a surface circulation to classify the system as Tropical Storm Debby, the fourth tropical system of the 2012 Atlantic hurricane season.
Debby is a lopsided tropical storm. The west side of the system is mostly cloud free, with almost all of the convection well off to the east of the center. The Air Force Recon plane found flight-level (1,500 feet) winds of about 50-55 knots (about 55-65 MPH), with the surface winds clocking in a little lower at 50 MPH.
The forecast models still show a great amount of uncertainty in the track of Debby. The NHC has decided to go with the westerly track, raking the storm up against the Louisiana coast and eventually hitting Texas. Here's the NHC's discussion in regard to the storm's track:
DEBBY IS MOVING SLOWLY NORTHWARD...OR 360 DEGREES AT 5 KT. THE
CYCLONE IS IN A WEAK STEERING ENVIRONMENT BETWEEN TWO MID-LEVEL
RIDGES LOCATED OVER THE GREATER ANTILLES AND THE SOUTHERN UNITED
STATES...AND DEBBY IS NOT EXPECTED TO MOVE MUCH DURING THE NEXT
COUPLE OF DAYS. THE TRACK GUIDANCE IS SPLIT IN TWO BRANCHES...WITH
THE GFS AND GFDL SHOWING AN EASTWARD MOTION ACROSS FLORIDA...AND
THE REST OF THE MODELS BRINGING DEBBY WESTWARD ACROSS THE NORTHERN
GULF TOWARDS TEXAS. EVEN THOUGH THE DETERMINISTIC GFS SHOWS AN
EASTWARD TRACK...MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS ARE IN
AGREEMENT WITH THE WESTWARD-MOVING MODELS...MAKING THE WESTWARD
SCENARIO SEEM MORE LIKELY. IT IS IMPORTANT TO NOTE TOO THAT THE
ECMWF MODEL SHOWS A FASTER WESTWARD MOTION THAN INDICATED IN THE
NHC FORECAST...SO IT IS POSSIBLE THAT DEBBY COULD REACH THE COAST
EARLIER THAN INDICATED.
Here's the official forecast path for Tropical Storm Debby. The NHC has the system turning off towards the west, with the strongest rain and winds impacting the Louisiana coast. New Orleans is not in the tropical storm warning.
Areas in blue are under a tropical storm warning. Keep in mind that these warnings are in effect for the coastal counties, not just the immediate coast itself.
Towards the end of the forecast period, Debby is expected to slowly strengthen into a borderline hurricane. Forecasting the intensity of tropical systems is an inexact science. Debby could approach the coast as a Tropical Storm or Hurricane. If you live along the Louisiana or Texas coasts, you need to keep a very close eye on this system and start making preparations for a potential landfall in your area.
What to Expect:
Heavy Rain/Flooding: Tropical systems are, for the most part, heavy rain producers. Anyone from coastal Florida to coastal Texas needs to keep an eye on the track of Debby and take extra precautions if you're in a flood prone area. The following image is a rainfall forecast issued by the HPC this morning. The totals are in inches, and it's a 5 day total accumulated rainfall forecast.
Wind: A tropical storm warning is in effect for parts of the Louisiana coast, meaning that tropical storm force winds (45-75 MPH with higher gusts) are likely to occur over the next 24 to 48 hours as this system approaches. As Debby is expected to slowly strengthen as it makes its way towards the coast (and eventually turns westward towards Texas), residents need to take precautions to minimize as much as possible the threat of loose objects blowing around in high winds.
Tornadoes: As with any landfalling tropical system, tornadoes are a threat. The tornadoes usually aren't much stronger than EF-0 or EF-1, but a tornado is a tornado nonetheless. Keep a close eye on the weather and be prepared to take immediate action if a tornado warning is issued.
Evacuations: If you live in an area that receives an evacuation order, don't willfully ignore it. If possible, evacuate the area when told. If you can't evacuate, see if you can go with a close friend or relative. If you stay (either willfully or due to circumstance), be prepared to face those issues that arise when a storm hits.
I'll post another update on this storm late tonight, with subsequent updates throughout the weekend and into the week as this storm approaches the coast. Stay tuned to the National Hurricane Center, National Weather Service, and other official media outlets for the latest information.
National Hurricane Center
National Weather Service
Storm Prediction Center
National Weather Service Mobile AL
National Weather Service New Orleans LA
National Weather Service Lake Charles LA
National Weather Service Houston TX
National Weather Service Brownsville TX
2:50 PM PT: You can follow the Hurricane Hunters live with data coming online in real time using this Google Earth link. Clicking the link opens your computer's Google Earth software and loads the link to the live data stream.
9:22 PM PT: Tropical Storm Debby is still pretty much the same as it was earlier in the afternoon. The track remained relatively unchanged from the 500PM advisory. The NHC still expects it to make a sharp westerly turn towards the central Texas coast later in the week, and drag tropical storm force winds/heavy rain across the Louisiana/Texas coasts. Winds are still at 50 MPH and the NHC bumped up their forecast to have Debby reach Category 1 hurricane strength by Wednesday/Thursday. The track and intensity forecast can and will change over the next few days, so keep a close eye on this storm and check with the NHC every few hours for updates. Here's the latest position and forecast track map: