650
WTNT41 KNHC 290242
TCDAT1
TROPICAL STORM NOEL DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL162007
1100 PM EDT SUN OCT 28 2007
NOEL HAS NOT BECOME BETTER ORGANIZED OVER THE PAST FEW HOURS
ALTHOUGH IT CONTINUES TO PRODUCE STRONG CONVECTION PRIMARILY IN
CLUSTERS OVER THE NORTHEASTERN PORTION OF THE CIRCULATION. SOME OF
THIS CONVECTION HAS BEEN SPREADING OVER HISPANIOLA AND IS LIKELY
GENERATING VERY HEAVY RAINS OVER PORTIONS OF THAT ISLAND. DVORAK
INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND SAB...BUT BASED ON THE
EARLIER AIRCRAFT OBSERVATIONS THE CURRENT INTENSITY IS KEPT AT 50
KT. ANOTHER RECONNAISSANCE PLANE IS SCHEDULED TO INVESTIGATE NOEL
AROUND 0600 UTC TO GIVE A NEW ESTIMATE OF THE STRENGTH AND POSITION
OF THE TROPICAL CYCLONE.
IT IS DIFFICULT TO FIX THE LOCATION OF THE CIRCULATION CENTER BASED
SOLELY ON CONVENTIONAL SATELLITE IMAGERY. UTILIZING POSITION
ESTIMATES FROM EARLIER SSM/I AND AMSR-E MICROWAVE IMAGERY...THE
INITIAL MOTION IS A RATHER UNCERTAIN 330/4. NOEL IS APPARENTLY
EMBEDDED WITHIN THE EASTERN PORTION OF A MID- TO UPPER-LEVEL
CYCLONIC CIRCULATION WITH A WEAKENING SUBTROPICAL ANTICYCLONE A
LITTLE FARTHER TO THE NORTH. BOTH OF THESE FEATURES ARE FORECAST
TO WEAKEN AS A MID-LEVEL SHORTWAVE TROUGH APPROACHES FROM THE
NORTHWEST. THIS STEERING PATTERN EVOLUTION SHOULD CAUSE NOEL TO
GRADUALLY TURN NORTHWARD IN A FEW DAYS. THE DYNAMICAL MODELS ARE
BASICALLY CLUSTERING INTO TWO POSSIBLE SOLUTIONS. THE GFS AND THE
ECMWF SUGGEST A WEAKER CYCLONE MOVING ON A GENERALLY
WEST-NORTHWESTWARD TRACK. HOWEVER...THE GFS SOLUTION LOOKS
QUESTIONABLE SINCE IT SPLITS NOEL INTO TWO LOWER-TROPOSPHERIC
VORTICITY MAXIMA WITHIN A DAY OR SO AND DEVELOPS A THIRD CENTER
FARTHER TO THE NORTHEAST WITHIN 72 HOURS. THE OFFICIAL TRACK
FORECAST IS CLOSE TO A CONSENSUS OF THE GFDL...GFDN...HWRF...U.K.
MET AND NOGAPS TRACKS. THIS IS VERY SIMILAR TO OUR PREVIOUS NHC
TRACK.
THE UPPER-LEVEL LOW HAS BEEN IMPARTING SOME SOUTHWESTERLY SHEARING
ON THE TROPICAL CYCLONE WHICH IS INHIBITING AN INCREASE IN
ORGANIZATION AT THIS TIME. DYNAMICAL GUIDANCE INDICATES THAT THIS
LOW WILL SOON FILL...CREATING AN UPPER-LEVEL WIND ENVIRONMENT MORE
CONDUCIVE FOR STRENGTHENING. A COMPLICATING FACTOR IS HOW MUCH THE
INTERACTION WITH THE MOUNTAINOUS TERRAIN OF HAITI AND EASTERN CUBA
WILL DISRUPT THE CIRCULATION OF NOEL. BY DAYS 3-5...INCREASING
WESTERLY SHEAR SHOULD INTERRUPT THE INTENSIFICATION PROCESS...AND
BY THE END OF THE PERIOD THE SYSTEM SHOULD BE LOSING ITS TROPICAL
CHARACTERISTICS AS IT INTERACTS WITH A FRONTAL ZONE.
FORECAST POSITIONS AND MAX WINDS
INITIAL 29/0300Z 17.1N 72.1W 50 KT
12HR VT 29/1200Z 18.3N 73.2W 50 KT...INLAND OVER HAITI
24HR VT 30/0000Z 19.7N 74.5W 60 KT...OVER WATER
36HR VT 30/1200Z 21.0N 75.7W 55 KT...INLAND OVER CUBA
48HR VT 31/0000Z 22.4N 76.1W 55 KT...OVER WATER
72HR VT 01/0000Z 25.0N 76.0W 55 KT
96HR VT 02/0000Z 28.0N 74.5W 50 KT
120HR VT 03/0000Z 31.0N 72.0W 45 KT...EXTRATROPICAL
FORECASTER PASCH/ROBERTS
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