WTPA45 PHFO 240846
TCDCP5

TROPICAL STORM HILDA DISCUSSION NUMBER   8
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP112009
1100 PM HST SUN AUG 23 2009

HILDA/S SATELLITE SIGNATURE HAS SHOWN SOME INCREASE IN ORGANIZATION
OVER THE PAST 6 HOURS...LEADING TO DVORAK CURRENT INTENSITY
ESTIMATES OF 3.5 FROM SAB...PGTW AND PHFO. GIVEN THIS CONSENSUS...
THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT WITH THIS 
ADVISORY. A 0338 UTC QUIKSCAT PASS WAS THE BASIS FOR INCREASING THE
34 KT WIND RADII WITHIN THE NORTHERN SEMICIRCLE.

INITIAL MOTION CONTINUES AT 280/10...AS HILDA REMAINS IN DEEP
EASTERLY FLOW SOUTH OF AN EAST-WEST RIDGE ALOFT ALONG 20N...AND A
SURFACE RIDGE ALONG 35N. THESE DEEP LAYER EASTERLIES ARE CREATING
MODERATE EASTERLY SHEAR OVER HILDA...AND ARE INHIBITING OUTFLOW IN
THE NORTHERN SEMICIRCLE. LITTLE CHANGE IN THIS SETUP IS EXPECTED IN
THE SHORT TERM...AND THE TRACK FORECAST CLOSELY FOLLOWS THE
PREVIOUS ADVISORY THROUGH 48 HOURS. AFTER 48 HOURS...HILDA/S MOTION
WILL BE LESS INFLUENCED BY A MID-LEVEL HIGH TO ITS NORTHEAST...AND
INCREASINGLY BY A MID-LEVEL HIGH BUILDING SOUTHWARD TO ITS
NORTHWEST. THIS WILL RESULT IN SOME SLOWING OF THE FORWARD MOTION
ON DAYS 3 AND 4...AND A REDUCTION OF THE VERTICAL SHEAR...WITH
HILDA CONTINUING TOWARD THE WEST. AS COMPARED TO THE PREVIOUS
ADVISORY...THIS TRACK FORECAST REPRESENTS A SLIGHTLY SLOWER FORWARD
MOTION ON DAYS 3 THROUGH 5. 

THE FORECAST TRACK TAKES HILDA OVER WATERS SUFFICIENTLY WARM TO
SUPPORT A HURRICANE...AND WITH HILDA ABLE TO SLOWLY INTENSIFY IN THE
FACE OF MODERATE SHEAR OVER THE PAST 2 DAYS...THIS TREND IS FORECAST 
TO CONTINUE. SOME EASING OF THE VERTICAL WIND SHEAR ON DAYS 3 AND 4 
IS EXPECTED TO ALLOW HILDA TO CONTINUE TO INTENSIFY. THIS INTENSITY 
FORECAST REPRESENTS AN INCREASE FROM THE PREVIOUS ADVISORY...AND IS 
CLOSE TO SHIPS AND LGEM...WHICH BOTH FORECAST HILDA TO BECOME A 
HURRICANE IN 24 TO 36 HOURS. 

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0900Z 14.3N 144.1W    55 KT
 12HR VT     24/1800Z 14.7N 145.7W    55 KT
 24HR VT     25/0600Z 15.0N 147.6W    60 KT
 36HR VT     25/1800Z 15.2N 149.5W    65 KT
 48HR VT     26/0600Z 15.2N 151.3W    65 KT
 72HR VT     27/0600Z 15.1N 154.3W    70 KT
 96HR VT     28/0600Z 15.1N 157.2W    70 KT
120HR VT     29/0600Z 15.0N 160.0W    75 KT
 
$$

FORECASTER BIRCHARD