000
WTNT41 KNHC 122057
TCDAT1
 
TROPICAL DEPRESSION SIX DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062011
500 PM EDT FRI AUG 12 2011
 
THE LOW PRESSURE SYSTEM THAT HAS BEEN EMBEDDED WITHIN A BAROCLINIC
ZONE OFF THE SOUTHEAST UNITED STATES COAST DURING THE PAST DAY OR
TWO HAS LOST ITS FRONTAL CHARACTERISTICS OVER THE WARM ATLANTIC
WATERS. IN ADDITION...DEEP CONVECTION HAS BEEN INCREASING OVER THE
WELL-DEFINED LOW-LEVEL CENTER DURING THE PAST SEVERAL HOURS. BASED
ON ITS PRESENTATION IN SATELLITE IMAGERY AND EARLIER BUOY
REPORTS...THIS SYSTEM IS BEING DESIGNATED AS A TROPICAL DEPRESSION
WITH AN INITIAL INTENSITY OF 30 KT. SIGNIFICANT STRENGTHENING IS
NOT FORECAST SINCE THE DEPRESSION SHOULD REMAIN WITHIN AN
ENVIRONMENT OF INCREASING SOUTHWESTERLY SHEAR...FAIRLY DRY
MID-LEVEL AIR...AND PROGRESSIVELY COOLER WATERS. THE OFFICIAL
INTENSITY FORECAST IS CLOSE TO THE LGEM. EXTRATROPICAL TRANSITION
IS EXPECTED TO OCCUR IN ABOUT 36-48 HOURS ONCE THE CYCLONE MOVES
OVER WATERS COOLER THAN 25C AND INTERACTS WITH AN APPROACHING
FRONTAL BOUNDARY.

THE DEPRESSION IS MOVING 065/14 AND IS EMBEDDED WITHIN DEEP-LAYER
SOUTHWESTERLY FLOW BETWEEN A RIDGE OVER THE CENTRAL ATLANTIC OCEAN
AND A TROUGH OFFSHORE OF THE U.S. EAST COAST. THIS FLOW PATTERN IS
NOT EXPECTED TO CHANGE MUCH OVER THE NEXT COUPLE OF DAYS AND THAT
SHOULD KEEP THE CYCLONE MOVING IN THE SAME GENERAL HEADING UNTIL IT
MERGES WITH A FRONT. THE OFFICIAL TRACK FORECAST IS A LITTLE FASTER
THAN THE MODEL CONSENSUS...AND CLOSE TO A BLEND OF THE GFS AND
ECMWF MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/2100Z 36.0N  63.9W   30 KT  35 MPH
 12H  13/0600Z 37.0N  61.4W   35 KT  40 MPH
 24H  13/1800Z 38.5N  57.8W   40 KT  45 MPH
 36H  14/0600Z 39.8N  53.9W   40 KT  45 MPH
 48H  14/1800Z 40.6N  49.8W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  15/1800Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI/STEWART