UPDATE: TD 13 has strengthened to Tropical Storm Lee with 40 MPH winds.
The Central Gulf Coast is gearing up for what could be a memorable Labor Day weekend as Tropical Depression 13 meanders its way towards the Louisiana Coast. A Tropical Storm Warning remains in effect for coastal counties from the Texas/Louisiana border eastward to the Mississippi/Alabama border. These warnings are expected to shift eastward towards Mobile/Pensacola as the system makes its way northeast. Due to Tropical Depression 13 moving incredibly slowly (NW at 2 MPH as of the 10AM CDT advisory), the track keeps shifting around as the storm's interaction with various weather features remains in question.
Here is the current track from the NHC, showing TD 13 becoming Tropical Storm Lee (or Maria, if something else in the Atlantic forms first) moving inland over the central Louisiana coast, meandering by New Orleans and moving through the Gulfport/Biloxi/Mobile area by Tuesday morning. Click to enlarge.
This tropical cyclone is the perfect example of why you shouldn't focus on titles (depression, storm or hurricane). TD 13/Lee will not be remembered for its winds, but its rain. There is an incredible amount of moisture with this system, and mix that with the fact that it's barely moving and all the moisture is concentrated on the eastern side of the system, it could spell a water disaster for low-lying and flood prone areas along the northern Gulf Coast.
Here's the forecast precip from this system along the Gulf Coast. Notice how it's all one color? That's because the rainfall pegs out the HPC's legend, which only goes up to 15 inches. The northern Gulf Coast can expect anywhere from 10 to 20 inches of rain this weekend, with some areas getting more if heavy rain squalls train over them.
In addition to the rain, TD 13 is expected to attain strong tropical storm status as it makes landfall and moves across New Orleans and Mobile. Here is the current NHC forecast for what will be Lee's winds. Keep in mind that intensity forecasting is an inexact science, and these numbers tend to have a large margin of error after a day or two out.
Here's a map from the NHC showing their forecast probabilities for areas experiencing winds of at least tropical storm force. The warmer the color, the higher the probability folks in those areas will feel tropical storm force winds. These probabilities will steadily increase for Louisiana, Mississippi and Alabama as TD13 organizes and becomes TS Lee.
As most of you know, I live in Mobile AL so I'm in the heart of this all. The first rain band with the storm just crossed over, and it's pouring like hell as I type this. It'll be interesting to see what my University does in regards to classes this weekend. I don't really want to walk a mile back and forth through heavily wooded areas on campus in driving rain and 50 MPH winds. I hear Jim Cantore is coming to either Mobile or New Orleans later today, so that's a sure sign it's going to get ugly very fast.
Here's the current radar out of Mobile:
Here are some links to help you keep track of this developing deluge:
NWS Lake Charles LA
Lake Charles LA Radar
NWS New Orleans LA
New Orleans LA Radar
NWS Mobile AL
Mobile AL Radar
National Hurricane Center
National Weather Service
Storm Prediction Center
FEMA
NHC Satellites
College of DuPage GOES Satellites
Wunderground Tropical Site
Florida State University Tropical Forecast Models
DailyKos Tropical Weather Link Library
The National Weather Service in Mobile is extremely concerned about flooding all across the northern Gulf Coast, and put out this Special Weather Statement earlier this morning. Jump the fold for the unedited statement in its entirety.
Special Weather Statement issued by NWS Mobile AL at 718AM Friday September 2 2011.
... Extreme heavy rainfall possible for Labor Day weekend along the
north central Gulf Coast...
Tropical Depression Thirteen is expected to gradually strengthen as
it drifts toward the Louisiana coast today. The north central Gulf
Coast region is in a favorable area for extremely heavy rainfall...
with the most intense period expected to be from Saturday evening
through midday Monday. It is not out the question for some areas
over coastal Alabama and northwest Florida to receive as much as 10
to 15 inches of rain... with locally higher isolated amounts possible
where tropical rainbands become established.
Along the coastal counties of Alabama and northwestern Florida...
showers and thunderstorms along the coast this morning will
gradually increase in coverage and intensity during the day. By noon
Saturday... one to two inches of rain may have fell over coastal
Alabama with locally higher amounts... mainly west of Pensacola and
very close to the coast.
From Saturday afternoon through Sunday night... periods of very heavy
rain are expected... again mainly near the coast but slowly spreading
north and northeast. Rainfall totals from Saturday afternoon through
Sunday night as much as 8 inches bringing the totals to around 10
inches or more... mainly over the coastal counties although some 4 to
5 inch amounts possible further inland. Scattered showers and
thunderstorms continue into the first of the week with spotty heavy
rain continuing.
Finally... the situation could be further exacerbated Saturday night
through early Monday as relative heavier rainfall becomes
established on the east side of the gradually strengthening tropical
cyclone. Given the current uncertainty associated with the forecast
track... exactly where the heaviest rainfall sets up will require
constant monitoring. Despite this... it is realized that our region
will be on the very wet east side of the storm system. Therefore...
our region is in for potentially extremely heavy rainfall. It must
be emphasized that 5 to 10 inches of rain could fall just in the
Saturday evening to early Monday time frame.
This type of rainfall will likely bring about isolated flash
flooding by Saturday night... if not earlier. This could expand into
areal flooding... eventually evolving upscale to local coastal river
flooding by late weekend through early next week... mainly affecting
the rivers of southeast Mississippi... coastal Alabama and the western
Florida Panhandle. A Flash Flood Watch will likely be issued by early
Friday for the period from mid-weekend through Monday.
Please stay tuned to local media outlets... NOAA Weather Radio... and
your local NWS web Page (see http://www.Srh.NOAA.Gov/...) for later
updates... graphical forecasts and fast breaking watch or warning
information. This is a potential very serious situation and now is
the time to begin preparations.