514
WTPA43 PHFO 062048
TCDCP3
HURRICANE ISELLE DISCUSSION NUMBER 27
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
1100 AM HST WED AUG 06 2014
ISELLE HAS NOT WEAKENED OVER THE PAST SIX HOURS...AND IN FACT
APPEARS TO HAVE STRENGTHENED A BIT. AIR FORCE HURRICANE HUNTERS
RECENTLY FOUND MAXIMUM FLIGHT LEVEL WINDS OF 85 KT...WHICH SUGGESTS
ABOUT 77 KT WHEN ADJUSTED TO THE SURFACE...AND THE SFMR FOUND
MAXIMUM SURFACE WINDS OF 72 KNOTS. THIS DATA SUGGESTS RAISING THE
ADVISORY INTENSITY TO 80 KT. THE WIND RADII HAVE BEEN ADJUSTED
SOMEWHAT TO BETTER MATCH WHAT WAS FOUND BY RECONNAISANCE...BUT MAY
STILL BE A BIT GENEROUS. ISELLE IS IN AN ENVIRONMENT OF MARGINAL SEA
SURFACE TEMPERATURES OF 26C...BUT THE WIND SHEAR OVER THE SYSTEM IS
CURRENTLY WEAK. A CLEARLY DEFINED EYE FEATURE HAS REDEVELOPED IN THE
INFRARED AND VISIBLE IMAGERY OVER THE PAST 12 HOURS.
THE GLOBAL MODELS AND THE SHIPS GUIDANCE BOTH SHOW THE SHEAR
REMAINING RELATIVELY WEAK THROUGH THE NEXT 24 HOURS...THOUGH THE SEA
SURFACE TEMPERATURES WILL REMAIN MARGINAL. SINCE THERE APPEARS TO BE
LESS OF A WINDOW FOR ISELLE TO WEAKEN SIGNIFICANTLY BEFORE REACHING
THE ISLANDS...WE ARE UPGRADING THE TROPICAL STORM WARNING FOR THE
BIG ISLAND TO A HURRICANE WARNING. THE FORECAST TRACK AND WIND RADII
ALSO NECESSITATE ISSUING A TROPICAL STORM WARNING FOR MAUI COUNTY.
IT IS IMPORTANT TO NOTE THAT REGARDLESS OF WHETHER ISELLE REACHES
THE BIG ISLAND AS A TROPICAL STORM OR MINIMAL HURRICANE...THE
IMPACTS WILL STILL BE VERY SIMILAR.
ALTHOUGH THE SEA SURFACE TEMPERATURES INCREASE ALONG THE FORECAST
TRACK BEYOND 36 HOURS...NORTHERLY WIND SHEAR IS EXPECTED TO INCREASE
SIGNIFICANTLY OVER ISELLE AS AN UPPER LEVEL TROUGH DIGS RAPIDLY JUST
TO THE NORTHWEST OF HAWAII. THIS SHOULD RESULT IN MORE RAPID
WEAKENING IN THE LONGER TERM.
THE FORECAST TRACK PHILOSOPHY HAS NOT CHANGED. ISELLE WILL CONTINUE
TO GRADUALLY GAIN LATITUDE TO THE SOUTH OF A RELATIVELY WEAK
SUBTROPICAL RIDGE SEVERAL HUNDRED MILES NORTH OF THE HAWAIIAN
ISLANDS. THIS FORECAST IS ESSENTIALLY A CONTINUATION OF THE PREVIOUS
TRACK FORECAST.
FORECAST POSITIONS AND MAX WINDS
INIT 06/2100Z 17.2N 145.9W 80 KT 90 MPH
12H 07/0600Z 17.7N 148.2W 75 KT 85 MPH
24H 07/1800Z 18.3N 151.2W 70 KT 80 MPH
36H 08/0600Z 18.9N 154.3W 65 KT 75 MPH
48H 08/1800Z 19.6N 157.6W 55 KT 65 MPH
72H 09/1800Z 20.7N 163.4W 45 KT 50 MPH
96H 10/1800Z 22.1N 168.3W 40 KT 45 MPH
120H 11/1800Z 23.4N 172.7W 40 KT 45 MPH
$$
FORECASTER R BALLARD
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