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NOAA > NWS > CPHC > FLOSSIE Archive > HURRICANE FLOSSIE DISCUSSION NUMBER 25
HURRICANE FLOSSIE DISCUSSION NUMBER 25

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WTPA42 PHFO 142105
TCDCP2

HURRICANE FLOSSIE DISCUSSION NUMBER 25
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092007
1100 AM HST TUE AUG 14 2007

AT 1800 UTC...UW-CIMMS ESTIMATED HURRICANE FLOSSIE WAS UNDERGOING ABOUT 25 KT OF SOUTHWEST SHEAR. GOOD OUTFLOW TO THE NORTH IS COUNTERED BY HAMPERED OUTFLOW ELSEWHERE AS THIS SHEAR REALLY BEGINS TO TAKE ITS TOLL. AIRCRAFT OBSERVATIONS SHOW FLOSSIE HAS AN OPEN EYEWALL TO THE SOUTHEAST...WITH AN EXTRAPOLATED SURFACE WIND OF 90 KT AS OF 1600 UTC. AN 1800 UTC VORTEX MESSAGE LIMITS THIS SPEED TO THE NORTHEAST EYEWALL...WITH WEAKER WINDS ELSEWHERE. CI VALUES OF 4.5 FROM CPHC AND SAB AS WELL AS 5.0 FROM JTWC...77 KT AND 90 KT...SHOW THIS SYSTEM HAS WEAKENED OVER THE PAST SIX HOURS. WE GIVE FLOSSIE AN INITIAL STRENGTH OF 90 KT FOR THIS RUN.

TRACK GUIDANCE DIVERGES SHARPLY BEYOND 24 HOURS AS EACH MODEL HANDLES THE DECLINE OF FLOSSIE DIFFERENTLY...BUT THE GUIDANCE MEAN HAS CHANGED LITTLE. THE FORECAST TRACK CLOSELY FOLLOWS THE ARC OF THE OLD TRACK...BUT AN INITIAL SLIGHT DEVIATION TO THE RIGHT WAS NEEDED GIVEN RADAR-DERIVED INITIAL MOTION OF 299 DEGREES. THIS WILL TAKE FLOSSIE A BIT CLOSER TO THE BIG ISLAND AT POINT OF CLOSEST APPROACH...BUT CONTINUED WEAKENING WILL MITIGATE THE EFFECT THIS CHANGE WILL HAVE ON THE BIG ISLAND. WE HAVE DECREASED THE TROPICAL STORM WIND RADIUS TO 90 NM WITHIN THE NORTHWEST AND NORTHEAST QUADRANTS BASED ON AIRCRAFT OBSERVATIONS AND SCATTEROMETER DATA. THIS RADIUS IS STILL LARGE ENOUGH TO AFFECT THE BIG ISLAND...PROMPTING CONTINUANCE OF THE TROPICAL STORM WARNING AND HURRICANE WATCH FOR THAT ISLAND. WE DO NOT ANTICIPATE THE NEED FOR WATCHES OR WARNINGS FOR THE SMALLER ISLANDS AT THIS TIME. RADAR SHOWS FLOSSIE FORWARD SPEED HAS SLOWED TO 9 KT AND THIS IS REFLECTED IN THE TRACK FORECAST AS WELL. HURRICANE FLOSSIE WILL PASS SOUTH OF THE MAIN HAWAIIAN ISLANDS...WEAKENING BELOW HURRICANE STRENGTH WITHIN 48 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 14/2100Z 17.3N 154.9W 90 KT
12HR VT 15/0600Z 18.0N 156.3W 80 KT
24HR VT 15/1800Z 18.9N 158.2W 75 KT
36HR VT 16/0600Z 19.8N 160.2W 65 KT
48HR VT 16/1800Z 20.6N 162.4W 55 KT
72HR VT 17/1800Z 22.0N 166.9W 40 KT
96HR VT 18/1800Z 23.3N 171.2W 35 KT
120HR VT 19/1800Z 24.4N 175.4W 25 KT

$$
FORECASTER POWELL

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