177 
 WTNT42 KNHC 120309
 TCDAT2
 TROPICAL STORM FRED DISCUSSION NUMBER  18...CORRECTED
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072009
 1100 PM AST FRI SEP 11 2009
 
 CORRECTED FOR DISCUSSION OF DVORAK ESTIMATES
 
 FRED CONTINUES TO PRODUCE DEEP CONVECTION...ALTHOUGH THE COLDEST
 CLOUD TOPS ARE NOW DISPLACED MORE THAN A DEGREE NORTH OF THE
 LOW-LEVEL CENTER. THIS DISPLACEMENT IS DUE TO ABOUT 20 KNOTS OF
 SOUTHERLY SHEAR AS ANALYZED BY THE SHIPS MODEL AND UW-CIMSS. DVORAK
 DATA T-NUMBERS AT 0000 UTC HAD DECREASED TO 2.5 FROM SAB AND 3.0
 FROM TAFB...WHILE FINAL T-NUMBERS AND CI-NUMBERS WERE 3.0 AND
 4.0...REPSECTIVELY. A QUIKSCAT PASS FROM AROUND 2100 UTC DID NOT
 SHOW ANY WINDS HIGHER THAN ABOUT 45 KNOTS. THE INITIAL INTENSITY OF
 50 KNOTS IS BASED ON A BLEND OF THE DVORAK FINAL T- AND CI-NUMBERS
 AND THE QUIKSCAT DATA...ASSUMING THAT RAIN WAS ATTENUATING THE WIND
 SIGNAL SOMEWHAT. WITH THE WIND SHEAR EXPECTED TO CONTINUE...AND
 FRED MOVING OVER MARGINAL SSTS AND INTO A MORE STABLE ENVIRONMENT
 ...GRADUAL WEAKENING IS EXPECTED THROUGH THE PERIOD. THE OFFICIAL
 FORECAST HAS BEEN ADJUSTED DOWNWARD FOR THE FIRST 24 HOURS TO
 ACCOUNT FOR THE INITIAL INTENSITY...AND IS SIMILAR TO THE PREVIOUS
 FORECAST AFTER THAT TIME...IN BEST AGREEMENT WITH THE LGEM MODEL.
 IT IS POSSIBLE THAT FRED COULD DISSIPATE BEFORE THE END OF THE
 5-DAY PERIOD...AS INDICATED BY THE SHIPS MODEL.
 
 A 2016 UTC SSMI PASS...A 1941 UTC SSMIS PASS...AND THE QUIKSCAT DATA
 ALL SUGGEST THAT THE LOW-LEVEL CENTER OF FRED IS LOCATED FARTHER
 SOUTHEAST THAN PREVIOUSLY ESTIMATED. THE INITIAL MOTION ESTIMATE IS
 VERY SLOW...060/02. A TURN TOWARD THE NORTH AND THE NORTHWEST WITH
 A GRADUAL INCREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT
 COUPLE OF DAYS AS THE DEEP-LAYER TROUGH OVER THE NORTH ATLANTIC
 BEGINS TO LIFT OUT. BY 72 HOURS...LOW- TO MID-LEVEL RIDGING WILL
 BUILD IN TO THE NORTH OF WHAT IS LEFT OF FRED...AND SHOULD IMPART A
 FASTER MOTION TOWARD THE  WEST-NORTHWEST THROUGH THE END OF THE
 PERIOD. THE TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
 SCENARIO...WITH THE EXCEPTION OF THE UKMET...WHICH IS A FAR
 SOUTHERN OUTLIER. THE NEW OFFICIAL FORECAST IS ADJUSTED TO THE
 RIGHT OF THE PREVIOUS TRACK DUE TO THE MORE EASTWARD INITIAL
 POSITION...AND IS NEAR OR JUST TO THE RIGHT OF THE TVCN MODEL
 CONSENSUS.
 
 THE INITIAL 34-KT AND 50-KT WIND RADII WERE ADJUSTED BASED ON THE
 QUIKSCAT DATA.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      12/0300Z 18.0N  33.6W    50 KT
  12HR VT     12/1200Z 18.1N  33.5W    40 KT
  24HR VT     13/0000Z 18.4N  33.6W    40 KT
  36HR VT     13/1200Z 19.2N  34.4W    35 KT
  48HR VT     14/0000Z 20.0N  35.9W    30 KT
  72HR VT     15/0000Z 22.0N  40.5W    25 KT...REMNANT LOW
  96HR VT     16/0000Z 23.5N  46.0W    20 KT...REMNANT LOW
 120HR VT     17/0000Z 25.0N  51.5W    20 KT...REMNANT LOW
  
 $$
 FORECASTER BRENNAN