WTPA45 PHFO 250911
TCDCP5

TROPICAL STORM HILDA DISCUSSION NUMBER  12
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP112009
1100 PM HST MON AUG 24 2009

HILDA IS STILL IN A SHEARED ENVIRONMENT WITH GOOD UPPER LEVEL
OUTFLOW TO THE SOUTHWEST AND MUCH POORER OUTFLOW TO THE NORTHEAST.
THE 15 KT VERTICAL SHEAR FROM THE EAST IS ABOUT 5 KT LESS THAN SIX
HOURS AGO...WHICH PROBABLY EXPLAINS THE CONTINUED SLOW NORTH AND
NORTHEASTWARD SPREADING OF THE HIGH LEVEL CLOUDS. DEEP CONVECTION
REMAINS LIMITED TO A SINGLE CLUSTER JUST SOUTH OF THE ESTIMATED
CIRCULATION CENTER. BOTH SAB AND JTWC CAME IN WITH CURRENT
INTENSITIES OF 3.5 WHILE PHFO INCREASED THE CURRENT INTENSITY TO
4.0. CONSIDERING THAT HILDA IS STILL BATTLING VERTICAL SHEAR...WILL
STICK WITH THE MAJORITY AND KEEP THE INITIAL INTENSITY AT 50 KT.

HILDA IS MOVING TO THE WEST OR 270 DEGREES AT A SLIGHTLY SLOWER 8
KT. OVER THE NEXT 24 HOURS...HILDA WILL BE IN DEEP EASTERLY FLOW
SOUTH OF A MID AND UPPER-LEVEL RIDGE EXTENDING EASTWARD FROM THE
HAWAIIAN ISLANDS AND THE LOW-LEVEL SUBTROPICAL RIDGE FARTHER TO THE
NORTH. GLOBAL MODELS SHIFT THE RIDGE ALOFT TO OVER AND SOUTHWEST OF
HAWAII...WHICH SHOULD TURN HILDA ON A MORE WEST-SOUTHWESTWARD
COURSE FROM 24 TO 72 HOURS. BEYOND 72 HOURS...THE GLOBAL MODELS
HAVE DIFFERENT SOLUTIONS BUT IN GENERAL DIG AN UPPER LEVEL
SOUTHWARD CLOSE TO THE HAWAIIAN ISLANDS. THE TROUGH ALOFT SHOULD
WEAKEN THE SURFACE RIDGE NORTHWEST OF HILDA...ALLOWING THE SYSTEM
TO ASSUME A WEST-NORTHWEST COURSE. THE FORECAST TRACK WHICH FOLLOWS
THE ABOVE SCENARIO IS ALMOST IN LOCK STEP WITH THE MODEL CONSENSUS
GUNA TCON AND TVCN. IT SHOULD BE POINTED OUT THAT NOGAPS CONTINUES
TO TAKE HILDA ON A MORE NORTHERN TRACK AFTER 48 HOURS. IT IS STILL
TOO EARLY TO TELL IF THIS IS A CORRECT MOVE.
 
THE SHIPS INTENSITY FORECAST SHOWS A GRADUAL RELAXATION OF THE
VERTICAL SHEAR PRESENTLY OVER HILDA...SO THERE REMAINS A CHANCE
THAT HILDA WILL STRENGTHEN SLIGHTLY OVER THE NEXT 24 HOURS. THE
INTENSITY FORECAST FOLLOWS GHMI...HWRF AND SHIPS WHICH STRENGTHEN
HILDA TO A HURRICANE AFTER 48 HOURS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/0900Z 14.8N 147.9W    50 KT
 12HR VT     25/1800Z 14.7N 149.1W    55 KT
 24HR VT     26/0600Z 14.6N 150.6W    55 KT
 36HR VT     26/1800Z 14.4N 152.0W    55 KT
 48HR VT     27/0600Z 14.2N 153.4W    60 KT
 72HR VT     28/0600Z 14.3N 156.2W    65 KT
 96HR VT     29/0600Z 15.0N 159.6W    70 KT
120HR VT     30/0600Z 17.0N 163.0W    75 KT
 
$$
FORECASTER CRAIG