WTPA45 PHFO 232102
TCDCP5

TROPICAL STORM HILDA DISCUSSION NUMBER   6
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP112009
1100 AM HST SUN AUG 23 2009

INFRARED IMAGERY INDICATES THAT HILDA HAS BECOME BETTER ORGANIZED
THIS MORNING...WITH A DISTINCT CURVED BAND OF DEEP CONVECTION
DEVELOPING ALONG THE SOUTHERN SIDE OF THE SYSTEM. DVORAK CI NUMBERS
FROM AROUND 1730Z CAME IN AT 2.5 FROM HFO...3.0 FROM SAB...3.5 FROM
JTWC...AND 3.2 FROM CIMSS ADT. AN AVERAGE OF THESE CI NUMBERS
YIELDS AN INTENSITY OF 45 KTS...WHICH IS ALSO THE MAXIMUM WIND
SPEED CALCULATED BY AN EARLIER QUIKSCAT PASS AT 1509Z.  THUS...THE
INITIAL INTENSITY IS INCREASED TO 45 KT. THE 34 KT RADII HAVE ALSO
BEEN EXPANDED BASED ON THE QUIKSCAT DATA.

THE FORWARD MOTION OF HILDA HAS ACCELERATED THIS MORNING...LIKELY DUE
TO HILDA BECOMING LESS INFLUENCED BY THE NEARBY ITCZ AND
INCREASINGLY STEERED IN THE DEEP EASTERLY FLOW BEING PRODUCED BY
RIDGING AT THE SURFACE AND ALOFT TO THE NORTH. THE NEW MOTION IS
280/10. 

HILDA IS FORECAST TO INTENSIFY SLIGHTLY AND CONTINUE ON A TRACK THAT
IS JUST NORTH OF DUE WEST THROUGH THE NEXT 48 HOURS AS RIDGING AT
THE SURFACE AND ALOFT REMAINS TO THE NORTH. THE NEW TRACK IS FASTER
THAN THE PREVIOUS PACKAGE TO ACCOUNT FOR THE FASTER FORWARD MOTION.
THE FORECAST FORWARD SPEED IS CLOSE TO THE HWRF...BUT THE TRACK HAS
BEEN SET ESSENTIALLY DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE. THE
FLOW ALOFT IS ALSO CREATING AROUND 15 KT OF EASTERLY VERTICAL WIND
SHEAR AND IS INHIBITING OUTFLOW ALONG THE NORTHEAST SIDE OF THE
SYSTEM. EVEN THOUGH HILDA WILL BE OVER SUFFICIENTLY WARM SST
VALUES...THIS SHEAR IS FORECAST TO ALLOW ONLY A SMALL AMOUNT OF
INTENSIFICATION OVER THE NEXT TWO DAYS. THE INTENSITY FORECAST IS
CLOSE TO THE PREVIOUS PACKAGE AND TO ICON.  

BY 72 HOURS...THE TRACK OF HILDA SHIFTS TO THE DUE WEST AS RIDGING
ALOFT STRENGTHENS OVER AND TO THE NORTHWEST OF THE HAWAIIAN ISLANDS
AS A DEEP UPPER TROUGH DIGS FAR EAST OF THE ISLANDS NEAR 140W. THE
GFS AND SHIPS FORECAST THE WIND SHEAR TO SHIFT MORE NORTHERLY AND
RELAX SLIGHTLY. SOME SLIGHT STRENGTHENING IS FORECAST TO REMAIN
CLOSE TO ICON INTENSITY GUIDANCE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/2100Z 14.0N 142.0W    45 KT
 12HR VT     24/0600Z 14.4N 143.5W    45 KT
 24HR VT     24/1800Z 14.8N 145.5W    50 KT
 36HR VT     25/0600Z 15.1N 147.5W    50 KT
 48HR VT     25/1800Z 15.2N 149.4W    50 KT
 72HR VT     26/1800Z 15.3N 152.6W    50 KT
 96HR VT     27/1800Z 15.3N 155.7W    55 KT
120HR VT     28/1800Z 15.3N 158.7W    55 KT
 
$$
FORECASTER WROE