Hurricane Iselle Number 27 Public Advisory and Discussion

WTPA33 PHFO 062357
TCPCP3

BULLETIN
HURRICANE ISELLE INTERMEDIATE ADVISORY NUMBER 27A
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
200 PM HST WED AUG 06 2014

…DANGEROUS HURRICANE ISELLE CONTINUES TO TAKE AIM ON HAWAII…

SUMMARY OF 200 PM HST…0000 UTC…INFORMATION
———————————————-
LOCATION…17.5N 146.8W
ABOUT 565 MI…910 KM ESE OF HILO HAWAII
ABOUT 770 MI…1240 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…90 MPH…150 KM/H
PRESENT MOVEMENT…WNW OR 285 DEGREES AT 16 MPH…26 KM/H
MINIMUM CENTRAL PRESSURE…982 MB…29.00 INCHES

WATCHES AND WARNINGS
——————–
CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY…

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A HURRICANE WARNING IS IN EFFECT FOR…
* HAWAII COUNTY

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* MAUI COUNTY

A TROPICAL STORM WATCH IS IN EFFECT FOR…
* OAHU

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. A WARNING IS TYPICALLY ISSUED 36
HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL STORM
FORCE WINDS…CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR
DANGEROUS. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE
RUSHED TO COMPLETION.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE SOMEWHERE WITHIN THE WATCH AREA WITHIN THE NEXT 48 HOURS.

INTERESTS IN KAUAI COUNTY AND THE NORTHWESTERN HAWAIIAN ISLANDS
SHOULD MONITOR THE PROGRESS OF ISELLE. WATCHES MAY BE REQUIRED FOR
ADDITIONAL ISLANDS LATER TODAY OR THURSDAY.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 200 PM HST…0000 UTC…THE EYE OF HURRICANE ISELLE WAS LOCATED
NEAR LATITUDE 17.5 NORTH…LONGITUDE 146.8 WEST. ISELLE IS MOVING
TOWARD THE WEST-NORTHWEST NEAR 16 MPH…26 KM/H…AND THIS MOTION
IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF DAYS. ON THE
FORECAST TRACK…ISELLE WILL PASS NEAR OR OVER THE BIG ISLAND OF
HAWAII THURSDAY NIGHT AND SOUTH OF THE SMALLER ISLANDS ON FRIDAY.

DATA FROM U.S. AIR FORCE RESERVE HURRICANE HUNTERS INDICATE THAT
MAXIMUM SUSTAINED WINDS REMAIN NEAR 90 MPH…150 KM/H…WITH HIGHER
GUSTS. SOME WEAKENING IS FORECAST DURING THE NEXT 48 HOURS.
HOWEVER…ISELLE MAY STILL BE A HURRICANE AS IT PASSES NEAR OR OVER
THE BIG ISLAND.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 35 MILES…55 KM…FROM
THE CENTER…AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140
MILES…225 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB…29.00 INCHES.

HAZARDS AFFECTING LAND
———————-
WIND…TROPICAL STORM CONDITIONS ARE EXPECTED ON THE BIG ISLAND OF
HAWAII THURSDAY…WITH HURRICANE CONDITIONS EXPECTED THURSDAY
NIGHT. TROPICAL STORM CONDITIONS ARE EXPECTED FOR PORTIONS OF MAUI
COUNTY THURSDAY NIGHT. TROPICAL STORM CONDITIONS ARE POSSIBLE OVER
OAHU THURSDAY NIGHT OR FRIDAY.

SURF…SWELLS GENERATED BY ISELLE WILL REACH THE MAIN HAWAIIAN
ISLANDS TODAY…WITH LARGE…DAMAGING SURF EXPECTED ALONG MAINLY
EAST AND SOUTH SHORES STARTING LATE TONIGHT OR THURSDAY.

RAINFALL…ISELLE IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 5 TO 8
INCHES…WITH ISOLATED MAXIMUM AMOUNTS TO 12 INCHES. THESE RAINS
COULD CAUSE LIFE-THREATENING FLASH FLOODS AND ROCK AND MUD
SLIDES.

STORM SURGE…THE COMBINATION OF A DANGEROUS STORM SURGE AND THE
TIDE WILL CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY
RISING WATERS. THE WATER COULD REACH THE FOLLOWING HEIGHTS ABOVE
GROUND IF THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE…

BIG ISLAND WINDWARD AND KAU…1 TO 3 FT

THE HIGHEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF
ONSHORE FLOW. THE SURGE WILL BE ACCOMPANIED BY LARGE AND DAMAGING
WAVES. SURGE RELATED FLOODING DEPENDS ON THE RELATIVE TIMING OF THE
SURGE AND THE TIDAL CYCLE…AND CAN VARY GREATLY OVER SHORT
DISTANCES.

NEXT ADVISORY
————-
NEXT COMPLETE ADVISORY…500 PM HST.

$$
FORECASTER R BALLARD

 

WWWW
000
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