Although the overall satellite presentation of the depression has changed little this evening...new bands of deep convection have developed to the southeast of the center. Satellite classifications and recent buoy observations support keeping the initial intensity at 30 kt. A NOAA hurricane hunter aircraft is scheduled to investigate the cyclone overnight. A shear analysis from UW-CIMSS shows about 20 kt of westerly shear over the cyclone. This shear is forecast to relax during the next 12-24 hours as an upper-level anticyclone builds over the Gulf. This is expected to result in a favorable environment for intensification. However...given the large size of the circulation...strengthening is expected to be gradual. The new NHC intensity forecast is nearly identical to the previous advisory and is a blend of the SHIPS/lgem guidance.
The depression has not moved much this evening...and the highly uncertain initial motion is 315/2 kt. Since the depression is still in the formative stage...the center could reform within the large circulation during the next 12-24 hours. This possibility is supported by the GFS...which shows the center reforming farther north within 24 hours. Steering currents are expected to remain weak during the next several days as the depression remains to the south of a weakening mid/upper level ridge. As the ridge slides eastward...it should allow the cyclone to move slowly northward... then northeastward. Although the dynamical models shows little overall motion during the next 2-3 days...there is a large spread in the guidance and lower than normal confidence in the track forecast. The updated NHC track is a little slower and east of the previous forecast.
Forecast positions and Max winds
init 02/0300z 26.6n 91.5w 30 kt 35 mph 12h 02/1200z 27.5n 92.2w 35 kt 40 mph 24h 03/0000z 28.0n 92.4w 40 kt 45 mph 36h 03/1200z 28.6n 92.4w 45 kt 50 mph 48h 04/0000z 29.2n 92.3w 50 kt 60 mph 72h 05/0000z 29.7n 92.1w 50 kt 60 mph...near the coast 96h 06/0000z 30.5n 91.5w 35 kt 40 mph...inland 120h 07/0000z 31.5n 90.0w 25 kt 30 mph...inland
http://www.nola.com/weather/index.ssf/2011/09/plodding_erratic_gulf_of_mexic.html
Plodding, erratic Gulf of Mexico storm puts Louisiana on alert
http://www.wwl.com/Tropics-update—A-ton-of-rain-on-the-way/10800505
Tropics update: A ton of rain on the way
http://www.nola.com/hurricane/index.ssf/2011/09/tropical_depression_13_forces.html
Tropical Depression 13 forces Gulf coast to brace for rain, flooding