Tropical Storm PHILIPPE

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SAT SEP 17 2005
 
CONVENTIONAL AND MCIROWAVE SATELLITE IMAGERY SUGGEST TROPICAL STORM
PHILIPPE HAS MOVED VERY LITTLE TO THE NORTH-NORTHWEST DURING THE
PAST 6 HOURS. A 17/2154Z QUIKSCAT OVERPASS SHOWED THE SURFACE
CENTER WEST OF 55W LONGITUDE...WHEREAS THE RECON POSITION NEAR THAT
TIME INDICATED A CIRCULATION CENTER EAST OF 55W. MY FEELING IS THAT
THE RECON CENTER WAS A SMALL CIRCULATION ROTATING NORTHWARD UP THE
EAST SIDE OF THE LARGER LOW-LEVEL CENTER...AND THAT THE TWO CENTERS
HAVE NOW CONSOLIDATED NEAR 55W. A BURST OF DEEP CONVECTION HAS
DEVELOPED OVER AND SOUTH OF THE ALLEGED LOW-LEVEL CENTER...AND
SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM TAFB...35 KT FROM
SAB...AND 25 KT FROM AFWA. DUE TO THE UNCERTAINTY IN THE EXACT
LOCATION OF THE CENTER...THE INITIAL INTENSITY IS AN AVERAGE OF THE
VARIOUS INTENSITY ESTIMATES. A RECON AIRCRAFT WILL BE INVESTIGATING
PHILIPPE AROUND 06Z.
 
THE INITIAL MOTION IS AN UNCERTAIN 335/4.  STEERING CURRENTS ARE
UNUSUALLY WEAK FOR THIS REGION OF THE ATLANTIC...AND PHILIPPE IS
EXPECTED TO MOVE SLOWLY NORTHWESTWARD AROUND THE SOUTHWESTERN
PERIPHERY OF A WEAK MID-LEVEL RIDGE THROUGHOUT THE FORECAST PERIOD.
BY THE END OF THE PERIOD...THE RIDGE IS FORECAST TO STRENGTHEN TO
THE NORTH OF THE CYCLONE...AND THAT MAY RESULT IN A MORE
WEST-NORTHWESTWARD MOTION THAN WHAT IS INDICATED BY THE OFFICIAL
FORECAST. THE NHC MODEL GUIDANCE IS RATHER DIVERGENT...BUT IS IN
GENERAL AGREEMENT ON THE FORECAST MOTION AND THE FORECAST TRACK IS
CLOSE TO THE MODEL CONSENSUS.
 
PHILIPPE IS FORECAST TO REMAIN OVER 30C AND WARMER SSTS FOR THE NEXT
5 DAYS...AND THE VERTICAL SHEAR IS EXPECTED TO BE LESS THAN 15 KT. 
THEREFORE...STEADY STRENGTHENING IS FORECAST SIMILAR TO THE
PREVIOUS ADVISORY AND THE LATEST SHIPS MODEL OUTPUT.
 
BASED ON THE MORE EASTWARD SHIFT IN THE FORECAST TRACK...WATCHES OR
WARNINGS ARE NOT ANTICIPATED AT THIS TIME FOR ANY PORTION OF THE
LESSER ANTILES. HOWEVER...WITH STEERING CURRENTS BEING RATHER WEAK
AND ILL-DEFINED...ANY WESTWARD SHIFT COULD REQUIRE WATCHES OR
WARNINGS AT SOME POINT IN THE FORECAST PERIOD.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0300Z 14.1N  55.2W    35 KT
 12HR VT     18/1200Z 14.9N  55.7W    40 KT
 24HR VT     19/0000Z 15.8N  56.4W    50 KT
 36HR VT     19/1200Z 17.0N  57.3W    60 KT
 48HR VT     20/0000Z 18.1N  58.3W    65 KT
 72HR VT     21/0000Z 20.6N  59.9W    75 KT
 96HR VT     22/0000Z 23.0N  61.0W    85 KT
120HR VT     23/0000Z 25.0N  62.0W    95 KT
 
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