461 
 WTNT42 KNHC 161435
 TCDAT2
  
 TROPICAL STORM GERT DISCUSSION NUMBER  11
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072011
 ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
 1100 AM AST TUE AUG 16 2011
  
 GERT CONTINUES TO WEAKEN THIS MORNING...WITH THE ASSOCIATED
 THUNDERSTORM ACTIVITY VIRTUALLY EVAPORATING AROUND 10Z.  MORNING
 SATELLITE IMAGERY...AND TO SOME DEGREE DETERMINISTIC MODEL
 GUIDANCE...IMPLIED THAT GERT HAS ABOUT 10 KNOTS OF NORTHEASTERLY
 VERTICAL WIND SHEAR DUE TO THE STRONGER SOUTHWESTERLY LOW-LEVEL
 FLOW CONFLICTING WITH LIGHTER SOUTHWEST WINDS AT THE 300 HPA LEVEL. 
 THE LOW-LEVEL CENTER REMAINS EXPOSED...THOUGH NEW CONVECTION IS
 TRYING TO DEVELOP ON ITS NORTHEAST SIDE WHICH COULD BE AN INDICATION
 OF A SWITCH IN THE DIRECTION OF THE VERTICAL WIND SHEAR TO
 SOUTHWESTERLY...WHICH WAS PREVIOUSLY ANTICIPATED.  THE INITIAL WIND
 SPEED HAS BEEN LOWERED TO 35 KT FOR THIS ADVISORY...IN LINE WITH
 THE CURRENT T-NUMBER FROM TAFB BUT HIGHER THAN THAT PROVIDED BY
 SAB.  THIS SYSTEM STILL HAS A FEW MORE HOURS BEFORE IT CROSSES THE
 26C ISOTHERM...WHICH SHOULD ALLOW IT TO RETAIN ITS CURRENT
 INTENSITY.  GERT IS FORECAST TO BECOME A POST-TROPICAL CYCLONE IN
 ABOUT 12 HOURS AS IT MOVES OVER WATERS NEAR 20C AND INTERACTS WITH
 THE APPROACHINIG COLD FRONT...WHICH COULD LEAD TO TEMPORARY
 RESTRENGTHENING...SO THE INTENSITY FORECAST HAS BEEN LEFT
 RELATIVELY UNCHANGED.  THE RESULTANT LOW PRESSURE AREA SHOULD LOSE
 DEFINITION WITHIN THE FRONTAL ZONE DURING THE DAY WEDNESDAY.
  
 THE TROPICAL STORM IS ACCELERATING INTO THE NORTH ATLANTIC
 WATERS...AND THE LATEST INITIAL MOTION ESTIMATE IS 040/26. THIS
 SYSTEM COULD ACCELERATE SLIGHTLY MORE AS GERT BECOMES INCREASINGLY
 STEERED BY THE STRONG LOW-LEVEL FLOW TO THE EAST OF A DEEP-LAYER
 TROUGH ALONG THE UNITED STATES EAST COAST. THE OFFICIAL FORECAST IS
 SLIGHTLY TO THE LEFT OF THE PREVIOUS ONE BUT REMAINS ON THE
 EASTWARD SIDE OF THE GUIDANCE ENVELOPE.  THE FORECAST TRACK AND
 TIMING OF EXTRATROPICAL TRANSITION INCORPORATE IDEAS COMMUNICATED
 BY THE OCEAN PREDICTION CENTER.
  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  16/1500Z 38.1N  57.5W   35 KT  40 MPH
  12H  17/0000Z 41.0N  54.2W   35 KT  40 MPH
  24H  17/1200Z 44.3N  49.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
  36H  18/0000Z...POST-TROP/EXTRATROP
  
 $$
 FORECASTER ROTH