Tropical Storm FERNANDA

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TROPICAL STORM FERNANDA DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062011
800 AM PDT TUE AUG 16 2011
 
SATELLITE IMAGES INDICATE THAT TROPICAL DEPRESSION SIX-E HAS
STRENGTHENED INTO A TROPICAL STORM.  THE CENTER IS NOW EMBEDDED
WITHIN CONVECTION...ALTHOUGH IT IS STILL ON THE NORTHEASTERN EDGE. 
THIS STRUCTURE IS CONFIRMED BY A TRMM PASS AT 0800 UTC WHICH SHOWED
THE CENTER JUST TO THE NORTHEAST OF THE MAIN BANDING FEATURE. 
DVORAK ESTIMATES ARE 35 AND 45 KT FROM SAB/TAFB...SO THE INITIAL
WINDS WILL BE INCREASED TO 40 KT.  

THE INTENSITY FORECAST FOR FERNANDA IS PROBLEMATIC.  WHILE SHEAR IS
FORECAST TO BE LIGHT FOR THE NEXT COUPLE OF DAYS...THE
THERMODYNAMIC ENVIRONMENT IS MARGINAL WITH MORE STABLE AIR AND
COOLER WATERS JUST TO THE NORTH.  HOWEVER...THE GUIDANCE IS NOW
SHOWING CONSIDERABLY MORE INTENSIFICATION...WITH THE
SHIPS/LGEM/HWRF MODELS NEAR HURRICANE STRENGTH IN A COUPLE OF DAYS. 
AFTER THAT TIME...AN INCREASE IN SOUTHEASTERLY SHEAR ALONG WITH
DECREASING SSTS SHOULD INDUCE A WEAKENING TREND.  ALTHOUGH THE NEW
NHC FORECAST IS HIGHER THAN THE PREVIOUS ONE...THE FORECAST WILL
STAY LOWER THAN THE BULK OF THE GUIDANCE GIVEN HOW CLOSE FERNANDA
IS TO MORE HOSTILE ENVIRONMENTAL CONDITIONS.

THE STORM IS MOVING TOWARD THE WEST AT ABOUT 7 KT.  A MID-LEVEL
RIDGE TO THE NORTH IS FORECAST TO WEAKEN DURING THE NEXT FEW
DAYS... WHICH SHOULD ALLOW FERNANDA TO GRADUALLY TURN TOWARD THE
WEST-NORTHWEST.  AFTER THAT TIME...A WEAKER CYCLONE IS EXPECTED TO
TURN TOWARD THE WEST WITHIN THE LOWER-LEVEL TRADES.  WHILE THE
RELIABLE GUIDANCE IS PRETTY WELL-CLUSTERED FOR THE FIRST FEW
DAYS...THERE ARE SOME SPEED DIFFERENCES.  THE NHC FORECAST IS CLOSE
TO AN AVERAGE OF THE PREVIOUS FORECAST...THE GFS AND ITS
ENSEMBLE...GFDL...ECMWF...AND UKMET MODELS.  THIS BLEND RESULTS IN
A SOMEWHAT FASTER AND FARTHER WEST FORECAST THAN THE PREVIOUS ONE.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/1500Z 12.3N 134.5W   40 KT  45 MPH
 12H  17/0000Z 12.3N 135.6W   45 KT  50 MPH
 24H  17/1200Z 12.5N 137.0W   50 KT  60 MPH
 36H  18/0000Z 12.8N 138.3W   50 KT  60 MPH
 48H  18/1200Z 13.2N 139.9W   45 KT  50 MPH
 72H  19/1200Z 14.2N 143.3W   40 KT  45 MPH
 96H  20/1200Z 14.5N 147.0W   35 KT  40 MPH
120H  21/1200Z 15.0N 151.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BLAKE
 
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