Tropical Depression ELEVEN

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TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112012
500 PM AST TUE AUG 28 2012
 
CONVECTION HAS INCREASED IN ASSOCIATION WITH THE AREA OF LOW
PRESSURE IN THE EASTERN TROPICAL ATLANTIC...AND THE SYSTEM IS NOW
CLASSIFIED AS A TROPICAL DEPRESSION. THE CENTER WAS EXPOSED EARLIER
TO THE SOUTHWEST OF THE DEEP CONVECTION DUE TO ABOUT 15 KT OF
WEST-SOUTHWESTERLY SHEAR...HOWEVER...THE CENTER HAS NOW REFORMED
CLOSER TO THE COLD CLOUD TOPS. THE INITIAL INTENSITY IS SET AT 30
KT FOR THIS ADVISORY IN AGREEMENT WITH THE LATEST DVORAK ESTIMATE
FROM SAB.
 
RGB AIRMASS IMAGERY FROM MET-9 SHOWS AN AREA OF DRY AIR TO THE WEST
OF THE CYCLONE...WHICH IN COMBINATION WITH THE SHEAR SHOULD RESULT
IN LIMITED INTENSIFICATION IN THE SHORT TERM. HOWEVER...IF THE DEEP
CONVECTION PERSISTS...THE CYCLONE COULD BECOME A TROPICAL STORM
SOON. OVERALL THE ATMOSPHERIC ENVIRONMENT DOES NOT APPEAR CONDUCIVE
FOR INTENSIFICATION DURING THE FORECAST PERIOD...WITH MODERATE
WESTERLY SHEAR EXPECTED TO PERSIST AS AN UPPER-LOW MOVES WESTWARD
AHEAD OF THE DEPRESSION FOR THE NEXT COUPLE OF DAYS. AS THE CYCLONE
MOVES AROUND THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE IN
ABOUT THREE DAYS THE SHEAR SHOULD BECOME MORE SOUTHWESTERLY AHEAD
OF A MID-/UPPER-LEVEL TROUGH MOVING OFFSHORE OF NORTH AMERICA. THE
NHC FORECAST SHOWS LITTLE CHANGE IN INTENSITY DURING THE FORECAST
PERIOD...AND ITS POSSIBLE THE CYCLONE COULD DISSIPATE AT SOME
POINT...AS SHOWN BY THE GFS MODEL.
 
THE INITIAL MOTION ESTIMATE IS A RATHER UNCERTAIN 285/09...AS THE
CENTER HAS BEEN REFORMING CLOSER TO THE DEEP CONVECTION. A WESTWARD
OR WEST-NORTHWESTWARD MOTION IS EXPECTED OVER THE NEXT 48 HOURS AS
THE CYCLONE WILL BE STEERED BY A NARROW MID-LEVEL RIDGE TO THE
NORTH. THE CYCLONE WILL REACH THE WESTERN EDGE OF THE RIDGE BY 72
HOURS AND A NORTHWARD AND NORTHEASTWARD ACCELERATION AHEAD OF THE
AFOREMENTIONED TROUGH IS EXPECTED AT DAYS 4 AND 5. THE NHC FORECAST
IS CLOSE TO A BLEND OF THE GFS AND ECMWF MODELS THROUGH 72 HOURS
AND IS CLOSE TO THE ECMWF AFTER THAT TIME. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/2100Z 23.8N  43.9W   30 KT  35 MPH
 12H  29/0600Z 24.1N  45.3W   35 KT  40 MPH
 24H  29/1800Z 24.3N  47.4W   35 KT  40 MPH
 36H  30/0600Z 24.6N  49.6W   35 KT  40 MPH
 48H  30/1800Z 25.3N  51.7W   35 KT  40 MPH
 72H  31/1800Z 27.5N  55.5W   35 KT  40 MPH
 96H  01/1800Z 32.5N  55.0W   35 KT  40 MPH
120H  02/1800Z 40.0N  48.0W   35 KT  40 MPH
 
$$
FORECASTER BRENNAN
 
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