WTPA45 PHFO 262109
TCDCP5

TROPICAL STORM HILDA DISCUSSION NUMBER  18
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP112009
1100 AM HST WED AUG 26 2009

THE DEEP CONVECTION WHICH FLARED UP OVERNIGHT HAS WANED OVER THE 
PAST FEW HOURS. EARLY MORNING VISIBLE SATELLITE SHOWS ISOLATED DEEP 
CONVECTION MAINLY OVER THE NORTHERN HALF OF THE SYSTEM. T-NUMBERS 
HAVE PRETTY MUCH LEVELED OFF IN THE 2.5 TO 3.0 RANGE OVER THE PAST 
18 HOURS. THE QUIKSCAT PASS THIS MORNING BARELY CAUGHT THE EASTERN 
HALF OF THE HILDA. WHILE DATA RELIABILITY AT THE EXTREME EDGE OF 
PASS IS SOMETHING TO CONSIDER...THE PASS DID SHOW 40 KNOT WINDS JUST 
EAST OF THE APPARENT CENTER. WITHOUT OVERRIDING EVIDENCE TO STRAY 
FROM PERSISTENCE...WILL KEEP THE INITIAL INTENSITY CONSTANT AT 40 
KT. 
 
TRACK POSITIONS OVER THE PAST 18 HOURS WERE RE-BESTED TO THE SOUTH 
BASED ON MICROWAVE IMAGERY. THIS SOUTHWARD SHIFTS FALLS BETTER IN 
LINE WITH THE CURRENT POSITION. HILDA/S WEST-SOUTHWEST MOTION IS 
EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS UNDER THE INFLUENCE OF A 
SURFACE HIGH AND UPPER LEVEL RIDGE NORTHWEST OF THE HAWAIIAN 
ISLANDS. THE HIGH IS FORECAST TO RETREAT OVER THE WEEKEND AND BE 
REPLACED BY A WEAK LOW AT THE SURFACE AND TROUGH ALOFT...WHICH WILL 
ALLOW HILDA TO GAIN SOME LATITUDE IN DAYS 3 THROUGH 5. GIVEN THE 
SOUTHWARD REBEST OF PREVIOUS POSITIONS AND TRACK VERIFICATION WHICH 
A NORTH BIAS OF NEARLY ALL THE GUIDANCE THUS FAR...HAVE SHIFTED THE 
TRACK FORECAST SLIGHTLY TO THE SOUTH. THE FORECAST FALLS WITHIN THE 
SOUTHERN HALF OF THE GUIDANCE ENVELOPE...SOUTH OF MOST CONSENSUS 
TRACKS WITH THE NOTABLE EXCEPTION OF TVCC WHICH LIES ALONG THE 
SOUTHERN BOUNDARY OF THE GUIDANCE ENVELOPE. VERY LITTLE CHANGE WAS 
MADE IN FORWARD MOTION.
 
MAJORITY INTENSITY GUIDANCE SUGGESTS RELATIVELY LITTLE CHANGE IN
INTENSITY OVER THE NEXT 5 DAYS. SHIPS...HWFI...AND LGEM ARE STILL
HOLDING ON TO STRENGTHENING BEYOND 24 HOURS.  PREVIOUS FORECAST
PACKAGE LOWERED THE STRENGTHENING THROUGHOUT 5 DAYS IN RESPONSE TO
INCREASED SHEAR IN THE NEXT FEW DAYS. THE CURRENT INTENSITY
FORECAST REFLECTS PERSISTENCE AND NO CHANGE FROM THE PREVIOUS.

FORECAST TAKES HILDA JUST SOUTH OF JOHNSTON ISLAND AS A TROPICAL
STORM IN DAYS 4 THROUGH 5. WILL CONTINUE TO MONITOR WHETHER ANY
WATCHES ARE WARRANTED FOR JOHNSTON ISLAND AS WE HEAD INTO THE 
WEEKEND.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/2100Z 13.1N 151.4W    40 KT
 12HR VT     27/0600Z 12.9N 152.5W    40 KT
 24HR VT     27/1800Z 12.7N 154.2W    40 KT
 36HR VT     28/0600Z 12.6N 156.0W    45 KT
 48HR VT     28/1800Z 12.8N 158.1W    45 KT
 72HR VT     29/1800Z 13.3N 163.1W    45 KT
 96HR VT     30/1800Z 14.6N 168.4W    40 KT
120HR VT     31/1800Z 16.9N 172.6W    40 KT
 
$$
FORECASTER TANABE