Tropical Cyclone Iselle Number 31 Public Advisory

WTPA33 PHFO 072040
TCPCP3
BULLETIN
HURRICANE ISELLE ADVISORY NUMBER 31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
1100 AM HST THU AUG 07 2014

…ISELLE WEAKER BUT REMAINS A SIGNIFICANT THREAT TO HAWAII…

SUMMARY OF 1100 AM HST…2100 UTC…INFORMATION
———————————————–
LOCATION…18.9N 152.2W
ABOUT 195 MI…315 KM ESE OF HILO HAWAII
ABOUT 405 MI…650 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…75 MPH…120 KM/H
PRESENT MOVEMENT…WNW OR 285 DEGREES AT 16 MPH…26 KM/H
MINIMUM CENTRAL PRESSURE…991 MB…29.27 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…INCLUDING THE ISLANDS OF MAUI…MOLOKAI…LANAI…
AND KAHOOLAWE.
* OAHU
* KAUAI COUNTY INCLUDING THE ISLANDS OF KAUAI AND NIIHAU.

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. 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.

INTERESTS IN THE NORTHWEST HAWAIIAN ISLANDS SHOULD MONITOR THE
PROGRESS OF ISELLE.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA…PLEASE MONITOR
PRODUCTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN
HONOLULU HAWAII.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 1100 AM HST…2100 UTC…THE CENTER OF HURRICANE ISELLE WAS
LOCATED NEAR LATITUDE 18.9 NORTH…LONGITUDE 152.2 WEST. ISELLE
CONTINUES TO MOVE TOWARD THE WEST-NORTHWEST NEAR 16 MPH…26
KM/H…AND THIS MOTION IS EXPECTED TO CONTINUE THROUGH FRIDAY. ON
THE FORECAST TRACK…ISELLE WILL BE MOVING OVER THE BIG ISLAND
TONIGHT…AND PASSING SOUTH OF THE SMALLER ISLANDS ON FRIDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 75 MPH…120 KM/H…WITH HIGHER
GUSTS. WEAKENING IS FORECAST DURING THE NEXT 48 HOURS…AND ISELLE
MAY WEAKEN TO A TROPICAL STORM TONIGHT.

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…220 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB…29.27 INCHES.

HAZARDS AFFECTING LAND
———————-
WIND…CONDITIONS WILL STEADILY DETERIORATE OVER THE BIG ISLAND THIS
AFTERNOON…WITH TROPICAL STORM CONDITIONS EXPECTED TO ARRIVE WELL
BEFORE DARK. HURRICANE CONDITIONS ARE LIKELY FOR PORTIONS OF THE
BIG ISLAND TONIGHT. TROPICAL STORM CONDITIONS ARE EXPECTED OVER MAUI
COUNTY TONIGHT…AND FOR OAHU LATE TONIGHT AND FRIDAY. TROPICAL
STORM CONDITIONS ARE EXPECTED FOR KAUAI COUNTY LATER FRIDAY.

RAINFALL…RAINFALL TOTALS OF 5 TO 8 INCHES…WITH ISOLATED MAXIMUM
AMOUNTS TO 12 INCHES…ARE EXPECTED ALONG THE TRACK OF ISELLE.
THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AS WELL AS
ROCK AND MUD SLIDES.
SURF…SWELLS GENERATED BY ISELLE WILL CONTINUE TO BUILD ALONG EAST
FACING SHORES TONIGHT. VERY LARGE…DAMAGING SURF IS EXPECTED ALONG
MAINLY EAST AND SOUTH SHORES STARTING EARLY THURSDAY.

STORM SURGE…THE COMBINATION OF 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 2 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 INTERMEDIATE ADVISORY…200 PM HST.
NEXT COMPLETE ADVISORY…500 PM HST.

$$
FORECASTER R BALLARD

WTPA43 PHFO 072050
TCDCP3

HURRICANE ISELLE DISCUSSION NUMBER 31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
1100 AM HST THU AUG 07 2014

ISELLE CONTINUES TO GRADUALLY WEAKEN. THE EYE IS NO LONGER EVIDENT
IN SATELLITE IMAGERY…AND THE RECONNASIANCE AIRCRAFT FOUND THE
SURFACE PRESSURE AT THE CENTER HAD RISEN A COUPLE OF MILLIBARS.
MAXIMUM FLIGHT LEVEL WINDS ON THE NORTHEAST SIDE OF THE CYCLONE WERE
69 KT…WHICH SUGGESTS MAXIMUM SURFACE WINDS NEAR 60 KT. OTHER
REDUCTION FACTOR TECHNIQUES WERE SUGGESTING 60 TO 65 KT MAXIMUM
SUSTAINED SURFACE WINDS. THUS THE INTENSITY FOR THIS ADVISORY IS
BEING LOWERED TO 65 KNOTS…AND THIS COULD BE A LITTLE GENEROUS.

ISELLE IS STILL LOCATED IN A REGION OF RELATIVELY WEAK SHEAR BETWEEN
TWO UPPER LEVEL ANTICYCLONES…TO ITS EAST AND WEST. THE HURRICANE
HAS BEEN MOVING SLIGHTLY FASTER THAN THIS WEAKNESS…AND WILL START
TO FEEL INCREASING NORTHERLY SHEAR OVER THE NEXT 12 HOURS WHICH WILL
MAINTAIN A WEAKENING TREND DESPITE GRADUALLY INCREASING SEA SURFACE
TEMPERATURES. EVEN IF ISELLE REACHES THE BIG ISLAND AS A TROPICAL
STORM…SIGNIFICANT IMPACTS WILL STILL BE FELT FROM WIND…RAIN…
AND SURF.

BEYOND 12 HOURS…THE COMBINATION OF MUCH STRONGER NORTHERLY SHEAR
AND INTERACTION WITH THE BIG ISLAND TERRAIN IS EXPECTED TO WEAKEN
ISELLE FURTHER. THE TRACK GUIDANCE SHOWED A LITTLE MORE SPREAD FOR
THIS CYCLE…AND SHIFTED SOMEWHAT TO THE SOUTH BEYOND 24 HOURS…
LIKELY DUE TO UNCERTAINTIES WITH THE INTENSITY OF A WEAKER ISELLE.
THE OFFICIAL FORECAST THUS FOLLOWS A SIMILAR TREND WITH A SLIGHT
SOUTHWARD SHIFT BEYOND 24 HOURS. THE INTENSITY FORECAST IS LOWER
THAN THE CONSENSUS BEYOND 72 HOURS WHEN ISELLE IS EXPECTED TO
INTERACT WITH AN UPPER LEVEL LOW DIGGING SOUTH OVER THE NORTHWEST
HAWAIIAN ISLANDS. THERE IS A GOOD CHANCE ISELLE WILL NOT SURVIVE THE
INTERACTION WITH THIS UPPER TROUGH.

FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 18.9N 152.2W 65 KT 75 MPH
12H 08/0600Z 19.4N 154.5W 60 KT 70 MPH
24H 08/1800Z 19.9N 157.4W 55 KT 65 MPH
36H 09/0600Z 20.4N 160.0W 45 KT 50 MPH
48H 09/1800Z 20.9N 162.2W 40 KT 45 MPH
72H 10/1800Z 21.8N 166.2W 35 KT 40 MPH
96H 11/1800Z 23.7N 172.0W 30 KT 35 MPH
120H 12/1800Z 25.9N 178.5W 25 KT 30 MPH…POST-TROP/REMNT LOW

$$
FORECASTER R BALLARD

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