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Tropical Storm PHILIPPE (Text)

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER  27
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
500 PM AST FRI SEP 30 2011
 
THE STRUCTURE OF PHILIPPE HAS CHANGED LITTLE THROUGH THE DAY EXCEPT
THAT THE LOW-LEVEL CENTER HAS BEEN RE-COVERED BY DEEP CONVECTION
SINCE THE LAST ADVISORY.  THE INITIAL INTENSITY IS BEING HELD AT 45
KT BASED ON THE EARLIER ASCAT PASS...AND THIS IS SUPPORTED BY
DVORAK ESTIMATES OF T3.0 FROM TAFB AND T2.9 FROM THE UW-CIMSS ADT. 
HILARY IS CURRENTLY LOCATED WITHIN A COL REGION BETWEEN AN
UPPER-LEVEL LOW TO ITS SOUTH AND A LARGE DEEP-LAYER TROUGH COVERING
THE EASTERN ATLANTIC.  HOWEVER...THE CYCLONE WILL BE EXITING THE
COL REGION WITHIN THE NEXT 12 HOURS OR SO AND IS FORECAST TO BE
CONTINUOUSLY BLASTED BY STRONG NORTHERLY SHEAR FOR THE NEXT SEVERAL
DAYS.  IN FACT...THE SHIPS MODEL DIAGNOSTICS ARE INDICATING UP TO
40 KT OF SHEAR WITHIN ABOUT 24 HOURS.  IT IS PARADOXICAL...
HOWEVER...THAT NEARLY EVERY INTENSITY MODEL IS EITHER SHOWING
PHILIPPE MAINTAINING ITS INTENSITY OR STRENGTHENING DURING THE
FORECAST PERIOD.  THIS IS HARD TO BELIEVE GIVEN THE HOSTILE
CONDITIONS EXPECTED...AND THE OFFICIAL INTENSITY FORECAST IS
CLOSEST TO THE LGEM MODEL...WHICH IS ALONG THE LOWER BOUND OF THE
GUIDANCE ENVELOPE.

PHILIPPE IS MOVING AT 320 DEGREES AT 11 KT AND IS FORECAST TO
GRADUALLY TURN WESTWARD OVER THE NEXT COUPLE OF DAYS AS IT COMES
UNDER THE INFLUENCE OF A BUILDING LOW- TO MID-LEVEL HIGH TO ITS
NORTH.  THE SPREAD IN THE TRACK GUIDANCE DOES NOT BECOME
SIGNIFICANT UNTIL AFTER 72 HOURS.  MOST OF THE GUIDANCE IS
INDICATING THAT PHILIPPE WILL RECURVE BY DAY 4 OR 5 AS IT
APPROACHES A DEEP-LAYER LONGWAVE TROUGH OVER THE WESTERN ATLANTIC. 
THE GFS IS A SOUTHERN OUTLIER AND KEEPS PHILIPPE ON A WESTWARD
COURSE...MOST LIKELY BECAUSE IT APPEARS TO DE-AMPLIFY THE WESTERN
ATLANTIC TROUGH SOONER THAN THE OTHER MODELS.  THE OFFICIAL TRACK
FORECAST SHOWS THE BEGINNING OF A SLOW RECURVATURE BY DAY 5 BUT IS
TO THE SOUTHWEST OF THE TVCA CONSENSUS AND NOT AS FAST AS THE 12Z
ECMWF AND UKMET MODELS AT THAT TIME.

FORECAST POSITIONS AND MAX WINDS
 
INIT  30/2100Z 23.5N  46.2W   45 KT  50 MPH
 12H  01/0600Z 24.2N  47.6W   45 KT  50 MPH
 24H  01/1800Z 25.0N  49.4W   40 KT  45 MPH
 36H  02/0600Z 25.7N  51.2W   40 KT  45 MPH
 48H  02/1800Z 26.1N  53.0W   40 KT  45 MPH
 72H  03/1800Z 26.0N  57.0W   30 KT  35 MPH
 96H  04/1800Z 26.5N  61.0W   30 KT  35 MPH
120H  05/1800Z 28.5N  61.5W   35 KT  40 MPH
 
$$
FORECASTER BERG
 
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