WTPA35 PHFO 121756
TCPCP5

BULLETIN
TROPICAL STORM HILDA INTERMEDIATE ADVISORY NUMBER 27A
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
800 AM HST WED AUG 12 2015

…TROPICAL STORM HILDA NEARLY STATIONARY…

SUMMARY OF 800 AM HST…1800 UTC…INFORMATION
———————————————-
LOCATION…17.3N 151.7W
ABOUT 270 MI…440 KM SE OF HILO HAWAII
ABOUT 495 MI…800 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…NNW OR 335 DEGREES AT 1 MPH…4 KM/H
MINIMUM CENTRAL PRESSURE…1003 MB…29.62 INCHES

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

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WATCH IS IN EFFECT FOR…
* HAWAII COUNTY

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

INTERESTS ELSEWHERE IN THE HAWAIIAN ISLANDS SHOULD CONTINUE TO
MONITOR THE PROGRESS OF HILDA.

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 800 AM HST…1800 UTC…THE CENTER OF TROPICAL STORM HILDA WAS
LOCATED BY U.S. AIR FORCE RESERVE AIRCRAFT NEAR LATITUDE 17.3
NORTH…LONGITUDE 151.7 WEST. HILDA IS MOVING TOWARD THE
NORTH-NORTHWEST NEAR 1 MPH…4 KM/H. THIS SLOW MOTION IS EXPECTED TO
CONTINUE TODAY…FOLLOWED BY A GRADUAL TURN TOWARD THE WEST AND AN
INCREASE IN FORWARD SPEED TONIGHT THROUGH THURSDAY NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH…75 KM/H…WITH HIGHER
GUSTS. WEAKENING IS EXPECTED OVER THE NEXT COUPLE OF DAYS…AND
HILDA IS FORECAST TO BE A TROPICAL DEPRESSION TONIGHT OR THURSDAY
AND A REMNANT LOW BY THURSDAY NIGHT.

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

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB…29.62 INCHES.

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

RAINFALL…HILDA MAY PRODUCE 6 TO 12 INCHES OF RAINFALL…WITH
MAXIMUM VALUES OF UP TO 18 INCHES POSSIBLE…ALONG AND NORTH OF ITS
PATH. THESE RAINS COULD RESULT IN LIFE THREATENING FLASH FLOODS AND
MUD SLIDES ACROSS PORTIONS OF THE HAWAIIAN ISLANDS TONIGHT INTO
SATURDAY.

NEXT ADVISORY
————-
NEXT COMPLETE ADVISORY…1100 AM HST.

$$
FORECASTER KODAMA



WTPA45 PHFO 121439
TCDCP5

TROPICAL STORM HILDA DISCUSSION NUMBER 27
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
500 AM HST WED AUG 12 2015

PULSING DEEP CONVECTION CONTINUES IN THE EASTERN QUADRANT OF HILDA
AS STRONG VERTICAL WIND SHEAR PERSISTS. DATA FROM THE LAST PASSES
THROUGH HILDA BY U.S. AIR FORCE WEATHER RECONNAISSANCE AIRCRAFT
SUPPORTED AN INITIAL INTENSITY OF 40 KT. DVORAK CURRENT INTENSITY
VALUES FROM HFO AND JTWC CAME IN AT 3.0/45 KT…AND SAB HAD A 2.5/35
KT…WITH CIMSS ADT SUGGESTING 37 KT. A BLEND OF THESE VALUES IS IN
LINE WITH THE RECONNAISSANCE DATA…AND GIVEN THE PULSING OF THE
DEEP CONVECTION AND CONTINUED PARTIAL EXPOSURE OF THE LOW LEVEL
CIRCULATION…THE INITIAL INTENSITY IS LOWERED TO 40 KT. THE
RECONNAISSANCE DATA…A 0756 UTC ASCAT PASS…AND NEARBY NOAA BUOY
51004 OBSERVATIONS WERE USED TO FINE TUNE A REDUCTION IN THE WIND
AND SEAS RADII.

HILDA IS EXPECTED TO CONTINUE WEAKENING UNDER PERSISTENT VERTICAL
WIND SHEAR. THE LATEST CIMSS ANALYSIS ESTIMATES THE WESTERLY WIND
SHEAR TO BE NEARLY 40 KT…AND THE UPPER LEVEL TROUGH PRODUCING THE
STRONG UPPER LEVEL WINDS RESPONSIBLE FOR THE SHEAR WILL REMAIN IN
PLACE FOR THE NEXT FEW DAYS. THE FORECAST FOLLOWS ICON CLOSELY AND
IS LESS AGGRESSIVE WITH THE WEAKENING TREND THAN SHIPS AND LGEM.
HILDA IS EXPECTED TO WEAKEN TO A TROPICAL DEPRESSION TONIGHT OR
THURSDAY AND DEGENERATE TO A REMNANT LOW BY THURSDAY NIGHT.

HILDA WILL REMAIN IN A WEAK STEERING ENVIRONMENT FOR THE SHORT
TERM…ENSURING A SLOW MOVEMENT AS IT NEARS THE HAWAIIAN ISLANDS.
THE MID TO UPPER LEVEL TROUGH OVER THE REGION IS PRODUCING WESTERLY
WINDS ALOFT…WHILE A RATHER STRONG SURFACE HIGH FAR NORTH OF
HAWAII IS GENERATING A SHALLOW LAYER OF EASTERLY WINDS. U.S. AIR
FORCE WEATHER RECONNAISSANCE FOUND HILDA MAKING A SLOW DRIFT TO THE
NORTHWEST THROUGH MUCH OF THE NIGHT…AND THE INITIAL MOTION IS
TOWARD THE NORTHWEST…OR 305 DEGREES…AT 4 KT. THIS MOTION IS
EXPECTED TO HOLD TODAY…FOLLOWED BY A GRADUAL TURN TOWARD THE WEST
AND AN INCREASE IN FORWARD SPEED TONIGHT AND THURSDAY…AS HILDA
BECOMES INCREASINGLY SHALLOW AND STEERED BY THE LOW LEVEL TRADE WIND
FLOW. THE FORECAST TRACK CHANGED LITTLE FROM THE PAST ADVISORY AND
RUNS ALONG THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE.

DUE TO UNCERTAINTY IN THE SHORT TERM…THE TROPICAL STORM WATCH
WILL REMAIN POSTED FOR THE BIG ISLAND OF HAWAII.

FORECAST POSITIONS AND MAX WINDS

INIT 12/1500Z 17.5N 152.0W 40 KT 45 MPH
12H 13/0000Z 17.6N 152.5W 35 KT 40 MPH
24H 13/1200Z 17.6N 153.3W 30 KT 35 MPH
36H 14/0000Z 17.5N 154.6W 30 KT 35 MPH
48H 14/1200Z 17.4N 156.1W 25 KT 30 MPH…POST-TROP/REMNT LOW
72H 15/1200Z…DISSIPATED

$$
FORECASTER WROE