WTPA35 PHFO 110832
TCPCP5

BULLETIN
HURRICANE HILDA ADVISORY NUMBER 22
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
1100 PM HST MON AUG 10 2015

…SLOW-MOVING HILDA MAINTAINING STRENGTH EAST-SOUTHEAST OF HAWAII…

SUMMARY OF 1100 PM HST…0900 UTC…INFORMATION
———————————————–
LOCATION…17.1N 150.9W
ABOUT 330 MI…530 KM ESE OF HILO HAWAII
ABOUT 540 MI…870 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…90 MPH…150 KM/H
PRESENT MOVEMENT…NW OR 315 DEGREES AT 5 MPH…7 KM/H
MINIMUM CENTRAL PRESSURE…981 MB…28.97 INCHES

WATCHES AND WARNINGS
——————–
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

INTERESTS IN THE MAIN HAWAIIAN ISLANDS SHOULD CONTINUE TO MONITOR
THE PROGRESS OF HILDA. A TROPICAL STORM WATCH MAY BE REQUIRED FOR
THE BIG ISLAND ON TUESDAY.
DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 1100 PM HST…0900 UTC…THE CENTER OF HURRICANE HILDA WAS
LOCATED NEAR LATITUDE 17.1 NORTH…LONGITUDE 150.9 WEST. HILDA IS
MOVING TOWARD THE NORTHWEST NEAR 5 MPH…7 KM/H…AND THIS GENERAL
MOTION IS EXPECTED TO CONTINUE THROUGH WEDNESDAY MORNING. A TURN
TOWARD THE WEST-NORTHWEST WITH A SLIGHT INCREASE IN FORWARD SPEED IS
EXPECTED WEDNESDAY NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 90 MPH…150 KM/H…WITH HIGHER
GUSTS. STEADY WEAKENING IS EXPECTED OVER THE NEXT 48 HOURS…WITH
HILDA FORECAST TO WEAKEN TO A TROPICAL STORM BY TUESDAY NIGHT.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES…35 KM…FROM
THE CENTER…AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70
MILES…110 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 981 MB…28.97 INCHES.

HAZARDS AFFECTING LAND
———————-
SURF…SWELLS ASSOCIATED WITH HURRICANE HILDA WILL PRODUCE LARGE
AND POTENTIALLY LIFE THREATENING SURF ALONG EAST AND SOUTHEAST
FACING SHORES OF PORTIONS OF THE HAWAIIAN ISLANDS OVER THE NEXT
COUPLE OF DAYS.

RAINFALL…HILDA IS EXPECTED TO PRODUCE VERY HEAVY RAIN OVER
PORTIONS OF THE HAWAIIAN ISLANDS FROM WEDNESDAY INTO THE WEEKEND.
THESE RAINS COULD CAUSE LIFE THREATENING FLASH FLOODS AND MUDSLIDES.

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

$$

FORECASTER BIRCHARD

WTPA45 PHFO 110846
TCDCP5

HURRICANE HILDA DISCUSSION NUMBER 22
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
1100 PM HST MON AUG 10 2015

DATA COLLECTED BY U.S. 53RD WEATHER RECONNAISSANCE AIRCRAFT WAS
CRITICAL IN DETERMINING THE INITIAL INTENSITY AND WIND STRUCTURE OF
HILDA THIS EVENING. ALTHOUGH HILDA IS ENCOUNTERING A PROVERBIAL
WALL OF SHEAR…WITH ANALYSES FROM UW-CIMSS INDICATING AROUND 35 KT
OF SOUTHWESTERLY SHEAR…HILDA HAS THUS FAR BEEN ABLE TO MAINTAIN
AN INNER CORE. MAXIMUM SFMR WINDS ON THE INITIAL PENETRATION WERE
NEAR 80 KT…AND A REDUCTION OF MAXIMUM FLIGHT LEVEL WINDS YIELDS
SURFACE WINDS 0F 77 KT…THUS THE INITIAL INTENSITY WILL BE
MAINTAINED AT 80 KT FOR THIS ADVISORY. A 25 TO 30 NM WIDE EYE WAS
NOTED BY THE FLIGHT CREW TO BE OPEN TO THE SOUTHWEST…WHICH WAS
NICELY HIGHLIGHTED BY 0405Z SSMI/S AND 0411Z GPM MICROWAVE
OVERPASSES. IN COORDINATION WITH CHIEF…AERIAL RECONNAISSANCE
COORDINATION…ALL HURRICANES /CARCAH/…FLIGHTS INTO HILDA WILL
BEGIN AT 6 HOURLY INTERVALS STARTING TUESDAY EVENING…WITH THE
NEXT MISSION SLATED FOR TUESDAY MORNING.

THE AIRCRAFT CENTER FIXES INDICATED THAT HILDA WAS MOVING VERY
SLOWLY…HAVING MOVED ABOUT 7 NM TOWARD THE NORTH-NORTHWEST IN 2
HOURS. A SLIGHTLY LONGER TERM INITIAL MOTION ESTIMATE FOR THIS
ADVISORY IS DETERMINED TO BE 315/04 KT. ALTHOUGH THE UPPER LEVEL
FLOW OVER HILDA FEATURES RELATIVELY STRONG WESTERLY WINDS…THE
CYCLONE IS CURRENTLY IN AN AREA OF LIGHT STEERING WINDS.

OVER THE NEXT 36 HOURS…HILDA IS FORECAST TO MOVE SLOWLY TOWARD
THE NORTHWEST…STEERED BY THE WEAK CURRENTS BETWEEN A LOW ALOFT
NORTH OF HAWAII…AND A HIGH TO THE DISTANT EAST. THIS WILL LEAD
TO GRADUAL WEAKENING…DUE TO STRONG UPPER LEVEL WESTERLIES SHEARING
AT LEAST THE UPPER PORTIONS OF THE CYCLONE NORTHEASTWARD. A TURN
TOWARD THE WEST-NORTHWEST AND A SLIGHT ACCELERATION ARE EXPECTED
THEREAFTER AS HILDA BECOMES INCREASINGLY SHALLOW AND THE VERTICAL
STRUCTURE OF THE CYCLONE BECOMES INCREASINGLY COMPROMISED. THE
OFFICIAL TRACK AND INTENSITY FORECASTS FOR THIS PACKAGE CLOSELY
FOLLOW THE PREVIOUS…WITH THE TRACK PARALLELING THE TVCN
CONSENSUS…AND CLOSE TO THE LATEST HWRF GUIDANCE. AFTER ACCOUNTING
FOR THE INITIAL INTENSITY…THE OFFICIAL FORECAST CLOSELY FOLLOWS
THE PREVIOUS…AND IS CLOSE TO SHIPS GUIDANCE THROUGH 48 HOURS. THE
RATE OF WEAKENING THEREAFTER IS CLOSE TO THE IVCN CONSENSUS…AND
SLOWER THAN SHIPS GUIDANCE…AND ANTICIPATES THAT HILDA WILL BECOME
A REMNANT LOW BY THE END OF THE FORECAST PERIOD.

ON THE FORECAST TRACK…A TROPICAL STORM WATCH MAY BE REQUIRED FOR
THE BIG ISLAND…POSSIBLY AS EARLY AS TUESDAY MORNING. UNCERTAINTY
REMAINS AS TO THE EVENTUAL IMPACTS THAT MAY BE FELT IN THE HAWAIIAN
ISLANDS FROM HILDA…BUT THE POTENTIAL FOR LARGE SURF AND VERY HEAVY
RAINFALL APPEARS TO BE INCREASING.

FORECAST POSITIONS AND MAX WINDS

INIT 11/0900Z 17.1N 150.9W 80 KT 90 MPH
12H 11/1800Z 17.5N 151.3W 70 KT 80 MPH
24H 12/0600Z 18.0N 152.0W 60 KT 70 MPH
36H 12/1800Z 18.5N 152.7W 50 KT 60 MPH
48H 13/0600Z 18.9N 153.7W 40 KT 45 MPH
72H 14/0600Z 19.3N 156.0W 35 KT 40 MPH
96H 15/0600Z 19.5N 158.5W 30 KT 35 MPH
120H 16/0600Z 20.0N 161.0W 25 KT 30 MPH…POST-TROP/REMNT LOW

$$

FORECASTER BIRCHARD