000
WTNT43 KNHC 170841
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST FRI AUG 17 2012
 
THE CLOUD PATTERN OF GORDON HAS DETERIORATED OVER THE PAST SEVERAL
HOURS WITH CENTRAL CONVECTION BECOMING LESS SYMMETRIC.  MICROWAVE
IMAGES SUGGEST THAT THE LOW-LEVEL CENTER IS LOCATED SOMEWHAT TO THE
SOUTHWEST OF THE MID-LEVEL CIRCULATION...PROBABLY A REFLECTION OF
WESTERLY SHEAR.  SATELLITE ESTIMATES HAVE COME DOWN A BIT...SO THE
INITIAL WIND SPEED IS REDUCED TO 55 KT.  A SMALL TROUGH SEEN TO THE
NORTHWEST OF GORDON IN WATER VAPOR IMAGES COULD HAVE HELPED CAUSED
THE RECENT INCREASE IN SHEAR.  MOST OF THE GLOBAL MODELS SHOW THIS
TROUGH WEAKENING...WHICH MIGHT ALLOW THE SHEAR TO DECREASE AGAIN. 
THE BULK OF THE GUIDANCE STILL PREDICT GORDON WILL BECOME A
HURRICANE BEFORE MOVING OVER COOLER WATERS IN A COUPLE OF
DAYS...THOUGH THE SHIPS AND LGEM MODELS HAVE BACKED OFF ON THIS
SOLUTION.  THE NHC FORECAST IS LOWERED FROM THE PREVIOUS ONE...BUT
STILL SHOWS GORDON BRIEFLY AS A HURRICANE.  THE NEW FORECAST IS
GENERALLY BELOW THE MODEL CONSENSUS...SHADED TOWARD THE SHIPS/LGEM
GUIDANCE.  

GORDON IS MOVING EASTWARD AT ABOUT 16 KT.  THE STORM IS BEING
STEERED TO THE SOUTH OF A LARGE TROUGH OVER THE NORTHEASTERN
ATLANTIC OCEAN...WHICH SHOULD CAUSE THE TROPICAL CYCLONE TO MOVE A
LITTLE SOUTH OF EAST FOR THE NEXT DAY OR SO.  AFTER THAT
TIME...GORDON WILL LIKELY BEGIN TO GAIN SOME LATITUDE AS A
SHORTWAVE MOVES DOWN THE WESTERN SIDE OF THE TROUGH.  MODELS
CONTINUE TO BE IN VERY GOOD AGREEMENT...AND ONLY A SMALL SOUTHWARD
CHANGE WAS MADE TO THE OFFICIAL FORECAST.   WHILE GORDON IS
EXPECTED TO MOVE NEAR THE AZORES IN ABOUT 3 DAYS...A COMBINATION OF
COLD WATER...INCREASING SHEAR...AND A NEARBY BAROCLINIC ZONE SHOULD
PROMOTE EXTRATROPICAL TRANSITION OF THE SYSTEM NEAR OR BEFORE IT
REACHES THOSE ISLANDS.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/0900Z 34.6N  48.1W   55 KT  65 MPH
 12H  17/1800Z 34.5N  45.3W   55 KT  65 MPH
 24H  18/0600Z 34.2N  41.4W   60 KT  70 MPH
 36H  18/1800Z 34.2N  37.5W   65 KT  75 MPH
 48H  19/0600Z 34.7N  33.7W   55 KT  65 MPH
 72H  20/0600Z 37.0N  26.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  21/0600Z 39.0N  19.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  22/0600Z 40.0N  17.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BLAKE