[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 222024
TCDAT2
TROPICAL STORM PHILIPPE DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT THU SEP 22 2005

ALTHOUGH I AM NOT CERTAIN THAT THE LOW-LEVEL VORTICITY CENTER OF
PHILIPPE ACTUALLY STILL HAS A CLOSED SURFACE WIND CIRCULATION...
THERE IS ENOUGH CONVECTION AND APPARENT ROTATION TO KEEP THE SYSTEM
AS A NOMINAL TROPICAL CYCLONE FOR THE TIME BEING.  PHILIPPE IS A
SMALL TROPICAL CYCLONE EMBEDDED WITHIN A BROAD NON-TROPICAL AREA OF
LOW PRESSURE.  THE INITIAL INTENSITY OF 35 KT IS BASED ON AN
EARLIER QUIKSCAT PASS AND A 30 KT SHIP REPORT SOUTHEAST OF THE
CENTER.  THE ENVIRONMENT IS CHARACTERIZED BY HIGH SHEAR AND DRY
MID-LEVEL AIR SWEEPING OVER THE CYCLONE FROM THE SOUTH.  A HIGHLY
DIFLUENT LARGE-SCALE UPPER FLOW IS LOCATED JUST TO THE CYCLONE'S
NORTH...BUT THIS PATTERN AND PHILIPPE APPEAR TO BE MOVING MORE OR
LESS IN TANDEM...SO I AM NOT EXPECTING THE CYCLONE TO BE ABLE TO
TAKE ADVANTAGE.  SOME INCREASE IN STRENGTH IS POSSIBLE AS PHILIPPE
BECOMES EXTRATROPICAL AND ACCELERATES NORTHEASTWARD BEFORE BECOMING
ABSORBED WITHIN A FRONTAL ZONE AFTER ABOUT 48 HOURS.

THE INITIAL MOTION IS 350/15.  PHILIPPE...WHICH IS A RELATIVELY
SHALLOW SYSTEM...IS EXPECTED TO ROTATE AROUND THE BROADER LOW IN
WHICH IT IS EMBEDDED FOR THE NEXT 12 TO 24 HOURS.  IN ABOUT 48
HOURS A FRONTAL ZONE SHOULD BE APPROACHING PHILIPPE FROM THE
NORTHWEST.  ALL GUIDANCE AGREES GENERALLY WITH THIS SCENARIO.
HOWEVER...AS THE FRONT APPROACHES THERE ARE SIGNIFICANT DIFFERENCES
AMONG THE MODELS...WITH THE NOGAPS AND UKMET ACCELERATING PHILIPPE
AND/OR THE NON-TROPICAL LOW NORTHEASTWARD...WHILE THE GFS AND GFDL
LEAVE PHILIPPE BEHIND OR MOVE IT NORTHEAST ONLY SLOWLY. THE OFFICIAL
FORECAST LEANS TOWARD THE FASTER SOLUTION AND IS IN BEST AGREEMENT
WITH THE 12Z UKMET RUN.

IT IS QUITE POSSIBLE THAT PHILIPPE WILL LOSE ITS CLOSED CIRCULATION
AND DISSIPATE MUCH EARLIER THAN SHOWN BELOW.


FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL      22/2100Z 27.5N  57.7W    35 KT
 12HR VT     23/0600Z 29.5N  59.2W    35 KT
 24HR VT     23/1800Z 31.3N  60.2W    35 KT
 36HR VT     24/0600Z 32.8N  60.2W    40 KT...EXTRATROPICAL
 48HR VT     24/1800Z 35.0N  58.0W    40 KT...EXTRATROPICAL
 72HR VT     25/1800Z...ABSORBED WITHIN FRONTAL ZONE


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