Hurricane FELICIA

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HURRICANE FELICIA DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP082009
800 PM PDT THU AUG 06 2009

FELICIA HAS CHANGED LITTLE IN ORGANIZATION OVER THE PAST SEVERAL
HOURS....WITH A WELL-DEFINED EYE AND EYEWALL CLOUD TOPS COLDER
THAN -70C IN SOME AREAS.  SATELLITE INTENSITY ESTIMATES ARE 115 KT
FROM TAFB AND SAB...AND THAT IS THE INITIAL INTENSITY FOR THIS
ADVISORY.  THE CIRRUS OUTFLOW IS GOOD IN THE WESTERN SEMICIRCLE AND
FAIR ELSEWHERE.

THE INITIAL MOTION IS 300/10.  FELICIA IS ON THE SOUTH SIDE OF THE
MID/UPPER-LEVEL SUBTROPICAL RIDGE...WITH A LARGE LOW-LEVEL RIDGE
DOMINATING THE AREA NORTH AND WEST OF THE CYCLONE.  WATER VAPOR
IMAGERY SHOWS AN UPPER-LEVEL LOW NEAR 23N153W.   THE DYNAMICAL
MODELS FORECAST THE LOW TO MOVE SLOWLY WESTWARD AND STRENGTHEN...
CAUSING A BREAK IN THE MID/UPPER-LEVEL RIDGE EAST OF HAWAII AND A
MID-LEVEL RIDGE TO DEVELOP NEAR THE HAWAIIAN ISLANDS.  THE MOST
LIKELY RESULT OF THIS EVOLUTION IS THAT AFTER 48 HR THE MID/UPPER-
LEVEL CIRCULATION OF FELICIA WOULD HAVE ITS WESTWARD MOTION
BLOCKED...WHILE THE LOW-LEVEL EASTERLY WINDS PUSHES THE LOW-LEVEL
CENTER WESTWARD.  THIS WOULD CAUSE FELICIA TO SHEAR APART AND THE 
REMAINING LOW-LEVEL CENTER TO MOVE GENERALLY WESTWARD.  THE
DYNAMICAL MODELS ARE IN GOOD AGREEMENT WITH THIS SCENARIO...
ALTHOUGH WITH SOME SPREAD.  THE GLOBAL MODELS...GFS...NOGAPS...
UKMET...AND ECMWF...ARE ON THE RIGHT SIDE OF THE GUIDANCE
ENVELOPE...WHILE THE HIGH-RESOLUTION HURRICANE MODELS...GFDL...
HWRF...AND GFDN...ARE ON THE LEFT SIDE.  THE NEW FORECAST TRACK IS
SIMILAR TO THE PREVIOUS ADVISORY...WITH A LITTLE MORE SOUTHWARD
MOTION AFTER 72 HR OUT OF RESPECT FOR THE HIGH-RESOLUTION MODELS. 
THE TRACK IS NEAR THE CENTER OF THE GUIDANCE ENVELOPE.

FELICIA IS CURRENTLY IN A LIGHT SHEAR ENVIRONMENT...AND THIS SHOULD
CONTINUE FOR THE NEXT 48 HR OR SO.  DURING THAT TIME...THE CYCLONE
SHOULD WEAKEN AS IT MOVES OVER PROGRESSIVELY COOLER SEA SURFACE
TEMPERATURES.  BETWEEN 48-72 HR...VERTICAL WIND SHEAR IS FORECAST TO
INCREASE AS FELICIA ENCOUNTERS THE WEATHER SYSTEMS DESCRIBED ABOVE
AND ASSOCIATED UPPER-LEVEL WESTERLIES.  THE DYNAMICAL MODELS SHOW
THE MID/UPPER-LEVEL CIRCULATION OF FELICIA DISSIPATING AS THIS
HAPPENS...WHICH OCCURS EVEN THOUGH THE FORECAST TRACK MOVES THE
CYCLONE OVER WARMER SSTS DURING THAT TIME.  THE INTENSITY FORECAST
FOLLOWS THIS SCENARIO AND CALLS FOR FELICIA TO CONTINUE WEAKENING
AFTER 48 HR.  WARMER SSTS AND LESS-HOSTILE ATMOSPHERIC CONDITIONS
ARE FORECAST SOUTH OF THE HAWAIIAN ISLANDS...AND IF FELICIA MOVES
TO THE LEFT OF THE FORECAST TRACK THE AFTER-48 HR WEAKENING COULD
BE SLOWER THAN CURRENTLY FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0300Z 16.9N 133.6W   115 KT
 12HR VT     07/1200Z 17.8N 134.9W   105 KT
 24HR VT     08/0000Z 18.7N 136.6W    90 KT
 36HR VT     08/1200Z 19.4N 138.9W    75 KT
 48HR VT     09/0000Z 19.8N 141.5W    65 KT
 72HR VT     10/0000Z 20.0N 147.0W    45 KT
 96HR VT     11/0000Z 19.5N 152.5W    35 KT
120HR VT     12/0000Z 19.0N 157.5W    25 KT
 
$$
FORECASTER BEVEN
 
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