[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 051456
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  46
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
1100 AM AST WED OCT 05 2011

PERSISTENT PHILIPPE CONTINUES AS A SHEARED TROPICAL CYCLONE WITH
VERY COLD CLOUD TOPS AND FREQUENT LIGHTNING ON THE DOWNSHEAR...OR
SOUTHEAST...SIDE OF THE CENTER.  INTENSITY ESTIMATES RANGE FROM
40 KT FROM AN 0839Z AMSU CIMSS ANALYSIS ON THE LOW END TO 55 KT
FROM THE TAFB DVORAK CURRENT INTENSITY NUMBER ON THE HIGH END.  55
KT IS RETAINED AS THE INITIAL INTENSITY...THOUGH THIS COULD BE
SLIGHTLY GENEROUS.  THE 34 KT WIND RADII WAS ADJUSTED OUTWARD SOME
BASED UPON THE 0839Z AMSU CIRA SIZE ANALYSIS.

A PAIR OF MICROWAVE IMAGES FROM FNMOC JUST BEFORE SYNOPTIC TIME
ALLOWS FOR A FAIRLY ACCURATE INITIAL POSITION.  BASED UPON THIS AND
THE FIRST VISIBLE IMAGES THIS MORNING THAT SUGGEST THAT THE CENTER
IS JUST TUCKED IN UNDERNEATH THE OVERCAST...AN INITIAL MOTION OF
310/5 IS ANALYZED.  THE CYCLONE IS ROUNDING THE SOUTHWESTERN
PERIPHERY OF A DEEP-LAYER RIDGE AND RECURVATURE SHOULD COMMENCE
SHORTLY.  THE GLOBAL AND HURRICANE REGIONAL MODELS ARE IN GOOD
AGREEMENT THAT A STRONG MID-LATITUDE TROUGH WILL TURN PHILIPPE
TOWARD THE NORTHEAST BY TOMORROW WITH INCREASING FORWARD SPEED.
THE TRACK FORECAST IS BASED UPON THE HURRICANE FORECAST IMPROVEMENT
PROGRAM MULTI-MODEL CONSENSUS AND IS NEARLY THE SAME AS THE
PREVIOUS ADVISORY.

PHILIPPE HAS A SHORT WINDOW OF OPPORTUNITY TO BECOME A HURRICANE.
THE WATER TEMPERATURES SHOULD REMAIN A WARM 28C UNDER THE TRACK OF
THE CYCLONE FOR THE NEXT TWO TO THREE DAYS.  HOWEVER...THE SYSTEM
HAS ONLY ABOUT 24 HOURS OF MODERATE VERTICAL SHEAR BEFORE THE
AFOREMENTIONED TROUGH CAUSES THE SHEAR TO INCREASE DRAMATICALLY.
ADDITIONALLY...PHILIPPE IS SURROUNDED BY QUITE DRY AIR AS SHOWN IN
THE TOTAL PRECIPITABLE WATER IMAGERY...THOUGH NOT MUCH OF THAT MAY
ACTUALLY BE REACHING THE CENTER OF THE STORM.  THE INTENSITY
GUIDANCE IS QUITE DIVERSE WITH LGEM AND SHIPS STATISTICAL MODELS
SHOWING LITTLE TO NO INTENSIFICATION...WHILE THE GFDL AND HWRF
DYNAMICAL MODELS ARE MUCH MORE AGGRESSIVE IN SPINNING UP THE
CYCLONE.  THE INTENSITY FORECAST IS CLOSE TO THE HFIP IV15
CONSENSUS THROUGH TWO DAYS AND THEN NEAREST TO THE SHIPS MODEL
THEREAFTER...WITH LITTLE CHANGE FROM THAT INDICATED IN THE PREVIOUS
ADVISORY.  EXTRATROPICAL TRANSITION IS UNANIMOUS BY ALL OF THE
DYNAMICAL GUIDANCE TO OCCUR BY 72 HOURS...WHICH IS WHEN THE
OFFICIAL FORECAST SHOWS THE TRANSITION.  AN 120 HOUR POINT IS
INCLUDED HERE AS ALL OF THE GUIDANCE...WITH THE PROMINENT EXCEPTION
OF THE ECWMF WHICH KILLS OFF THE STORM AFTER 72 HOURS... CONTINUES
PHILIPPE AS AN EXTRATROPICAL SYSTEM THROUGH AT LEAST FIVE DAYS.
THE OCEAN PREDICTION CENTER PROVIDED TRACK AND INTENSITY GUIDANCE
AT DAYS FOUR AND FIVE.


FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 25.3N  61.3W   55 KT  65 MPH
 12H  06/0000Z 26.0N  61.6W   60 KT  70 MPH
 24H  06/1200Z 27.0N  60.8W   65 KT  75 MPH
 36H  07/0000Z 28.2N  59.5W   60 KT  70 MPH
 48H  07/1200Z 29.3N  57.0W   55 KT  65 MPH
 72H  08/1200Z 34.0N  50.0W   55 KT  65 MPH
 96H  09/1200Z 40.5N  45.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  10/1200Z 46.0N  38.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
FORECASTER LANDSEA/BROWN



This weather bulletin was brought to you by:
www.nashvilleweather.net