Tropical Depression SEVEN

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TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072011
500 AM EDT SUN AUG 14 2011
 
TROPICAL DEPRESSION SEVEN HAS NOT BECOME ANY BETTER ORGANIZED SINCE
THE LAST ADVISORY.  IN FACT...THE LOW-LEVEL CENTER HAS MOVED FARTHER
AWAY FROM THE MAIN AREA OF DEEP CONVECTION IN THE PAST FEW HOURS. 
DVORAK CLASSIFICATIONS FROM TAFB AND SAB AT 0600 UTC WERE 30
KT...AND AN ASCAT PASS AT 0100 UTC SHOWED MAXIMUM WINDS IN THE 25
TO 30 KT RANGE.  BASED ON THESE DATA...THE INITIAL WIND SPEED IS
HELD AT 30 KT.  SOME STRENGTHENING OF THE DEPRESSION IS FORECAST
DURING THE NEXT 36 TO 48 HOURS AS IT REMAINS OVER RELATIVELY WARM
WATER AND IN A LOW TO MODERATE WIND SHEAR ENVIRONMENT.  HOWEVER...
GIVEN THE CURRENT LACK OF ORGANIZATION OF THE SYSTEM AND DRY AIR
AROUND IT...SIGNIFICANT STRENGTHENING APPEARS UNLIKELY.  THE
OFFICIAL INTENSITY FORECAST FOLLOWS THE INTENSITY MODEL CONSENSUS
AND IS A LITTLE LOWER THAN THE PREVIOUS ONE.  EXTRATROPICAL
TRANSITION IS NOW FORECAST TO OCCUR WITHIN 72 HOURS AS THE CYCLONE
CROSSES A VERY SHARP SEA SURFACE TEMPERATURE GRADIENT AND INTERACTS
WITH A DEEP-LAYER TROUGH.  BY DAY 4...THE POST-TROPICAL CYCLONE IS
EXPECTED TO BE ABSORBED BY A FRONT. 

THE DEPRESSION HAS TURNED A LITTLE TO THE RIGHT...AS EXPECTED...AND
THE INITIAL MOTION ESTIMATE IS 300/09.  A GRADUAL TURN TO THE NORTH
IS FORECAST DURING THE NEXT 24 TO 36 HOURS AS THE CYCLONE MOVES
AROUND THE PERIPHERY OF A SUBTROPICAL HIGH LOCATED OVER THE CENTRAL
ATLANTIC.  BEYOND THAT TIME...THE SYSTEM IS EXPECTED TO ACCELERATE
TO THE NORTH-NORTHEAST AS IT BECOMES EMBEDDED IN STRONGER FLOW
BETWEEN THE AFOREMENTIONED HIGH AND A TROUGH MOVING OFFSHORE OF THE
EASTERN UNITED STATES.  THE NEW OFFICIAL FORECAST IS SIMILAR TO THE
PREVIOUS ONE AND IS NEAR THE MULTI-MODEL CONSENSUS.  ONE SOURCE OF
UNCERTAINTY IN THE TRACK FORECAST IS THAT BOTH THE ECMWF AND UKMET
MODELS SHOW THE DEPRESSION INTERACTING WITH...OR ABSORBING...A
TROUGH OF LOW PRESSURE TO ITS SOUTHEAST.  IF THIS OCCURS...THE
DEPRESSION COULD MOVE SLOWER THAN CURRENTLY FORECAST.  
 
A TROPICAL STORM WARNING MAY BE REQUIRED FOR BERMUDA LATER TODAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/0900Z 28.5N  62.4W   30 KT  35 MPH
 12H  14/1800Z 29.4N  63.2W   35 KT  40 MPH
 24H  15/0600Z 31.2N  63.8W   40 KT  45 MPH
 36H  15/1800Z 33.7N  63.2W   45 KT  50 MPH
 48H  16/0600Z 37.3N  61.0W   45 KT  50 MPH
 72H  17/0600Z 45.5N  52.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  18/0600Z...ABSORBED BY FRONT
 
$$
FORECASTER CANGIALOSI/BRENNAN
 
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