WTPA33 PHFO 300246
TCPCP3

BULLETIN
HURRICANE IGNACIO ADVISORY NUMBER 21
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
500 PM HST SAT AUG 29 2015

…HAWAIIAN ISLANDS REMAIN VULNERABLE AS MAJOR HURRICANE IGNACIO
CONTINUES MOVING STEADILY NORTHWEST…

SUMMARY OF 500 PM HST…0300 UTC…INFORMATION
———————————————-
LOCATION…17.0N 147.6W
ABOUT 525 MI…845 KM ESE OF HILO HAWAII
ABOUT 735 MI…1180 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…140 MPH…220 KM/H
PRESENT MOVEMENT…NW OR 315 DEGREES AT 9 MPH…15 KM/H
MINIMUM CENTRAL PRESSURE…952 MB…28.12 INCHES

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

A TROPICAL STORM WATCH HAS BEEN ISSUED FOR MAUI COUNTY.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WATCH IS IN EFFECT FOR…
* MAUI COUNTY…INCLUDING THE ISLANDS OF MAUI…MOLOKAI…LANAI AND
KAHOOLAWE.
* HAWAII COUNTY

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA…GENERALLY WITHIN 48 HOURS OF THE
INITIAL ISSUANCE.

INTERESTS ELSEWHERE IN THE MAIN HAWAIIAN ISLANDS SHOULD CONTINUE TO
CLOSELY MONITOR THE PROGRESS OF IGNACIO.

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 500 PM HST…0300 UTC…THE EYE OF HURRICANE IGNACIO WAS LOCATED
NEAR LATITUDE 17.0 NORTH…LONGITUDE 147.6 WEST. IGNACIO IS MOVING
TOWARD THE NORTHWEST NEAR 9 MPH…15 KM/H…AND THIS MOTION IS
EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF DAYS. ON THE FORECAST
TRACK…THE CENTER OF IGNACIO IS EXPECTED TO PASS TO THE NORTHEAST
OF THE BIG ISLAND ON MONDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 140 MPH…220 KM/H…WITH HIGHER
GUSTS. IGNACIO IS A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. LITTLE CHANGE IN INTENSITY IS EXPECTED
TONIGHT AND A WEAKENING TREND IS EXPECTED TO BEGIN ON SUNDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES…45 KM…FROM
THE CENTER…AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140
MILES…220 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 952 MB…28.12 INCHES.

HAZARDS AFFECTING LAND
———————-
WIND…TROPICAL STORM CONDITIONS ARE POSSIBLE ON THE BIG ISLAND OF
HAWAII STARTING SUNDAY NIGHT…AND STARTING MONDAY ON MAUI.

RAINFALL…STORM TOTAL RAINFALL AMOUNTS OF 2 TO 4 INCHES…WITH
ISOLATED MAXIMUM AMOUNTS NEAR 6 INCHES MAINLY IN AREAS OF HIGHER
TERRAIN…ARE POSSIBLE IN THE WATCH AREA.

SURF…LARGE SWELLS GENERATED BY IGNACIO WILL ARRIVE ALONG EAST
AND SOUTHEAST FACING SHORES OF THE MAIN HAWAIIAN ISLANDS OVER THE
NEXT SEVERAL DAYS. RESULTANT SURF WILL BE LARGE AND POTENTIALLY
LIFE-THREATENING…ESPECIALLY ON THE BIG ISLAND LATER THIS WEEKEND
AND EARLY NEXT WEEK.

NEXT ADVISORY
————-
NEXT INTERMEDIATE ADVISORY…800 PM HST.
NEXT COMPLETE ADVISORY…1100 PM HST.

$$
FORECASTER R BALLARD

WTPA43 PHFO 300302
TCDCP3

HURRICANE IGNACIO DISCUSSION NUMBER 21
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
500 PM HST SAT AUG 29 2015

IGNACIO CONTINUES TO HAVE A WELL DEFINED…20 NM WIDE EYE SURROUNDED
BY A RING OF COLD CONVECTIVE CLOUDS. DVORAK INTENSITY ESTIMATES
WERE A UNANIMOUS 6.0 FROM THE SATELLITE AGENCIES…AND THE UW-CIMSS
ADT INTENSITY ESTIMATE WAS 6.4. BASED ON A BLEND OF THESE DATA…
WILL MAINTAIN THE 120 KT /CATEGORY 4 ON THE SAFFIR-SIMPSON SCALE/
INTENSITY. THE NEXT RECONNAISSANCE MISSION IS SCHEDULED TO
INVESTIGATE IGNACIO AT 0600 UTC. NOTE THAT HURRICANES IGNACIO AND
KILO ARE BOTH CATEGORY 4 AS OF THIS ADVISORY CYCLE…A VERY RARE
OCCURRENCE INDEED FOR THE CENTRAL PACIFIC BASIN.

THE HURRICANE IS MOVING STEADILY TOWARD THE NORTHWEST…315 DEGREES
AT 8 KT…THROUGH A WEAKNESS IN THE MID-LEVEL RIDGE EAST OF HAWAII
AND TOWARD A WEAK TROUGH LOCATED TO THE NORTH OF THE NORTHWESTERN
HAWAIIAN ISLANDS. THE TRACK GUIDANCE IS IN GOOD AGREEMENT THAT THIS
GENERAL MOTION WILL CONTINUE FOR THE NEXT FEW DAYS. OUR FORECAST
TRACK IS VERY CLOSE TO THE PREVIOUS FORECAST AS WELL AS THE
CONSENSUS GUIDANCE FOR THE NEXT 24 HOURS. BEYOND 24 HOURS OUR TRACK
BENDS MORE TO THE LEFT WITH TIME IN ANTICIPATION THAT IGNACIO WILL
WEAKEN A BIT FASTER THAN THE DYNAMICAL MODELS INDICATE.

THE UW-CIMSS WIND SHEAR ANALYSIS AND CONVENTIONAL SATELLITE IMAGERY
SHOWS THAT SOUTHWESTERLY WIND SHEAR IS BEGINNING TO AFFECT IGNACIO.
HIGH CLOUDS FROM THE HURRICANE ARE STARTING TO GET PULLED TO THE
NORTHEAST. ACCORDING TO THE ANALYSIS…THE SHEAR IS NEAR 10 KT…
BUT INCREASES TO 15-20 KT TO THE NORTHWEST OF THE CYCLONE…AND
WILL INCREASE FURTHER AND BECOME QUITE STRONG AS IGNACIO APPROACHES
HAWAII. THIS WILL LEAD TO A STEADY WEAKENING TREND…DESPITE SEA
SURFACE TEMPERATURES OF 27-28C ALONG MOST OF THE FORECAST TRACK.
THE WEAKENING WILL BE GRADUAL OVER THE NEXT 24 HOURS…THEN MORE
RAPID ONCE THE SHEAR BEGINS TO IMPACT THE CORE OF THE HURRICANE.
OUR WEAKENING TREND IS NOT AS FAST AS THE SHIPS…BUT FASTER THAN
THE DYNAMIC MODELS AND IN GOOD AGREEMENT WITH THE INTENSITY
CONSENSUS.

THE RELATIVELY CLOSE PROXIMITY TO THE EXPECTED OUTER EXTENT OF THE
34 KNOT WIND RADII IN THE SOUTHWEST QUADRANT REQUIRES MAINTAINING
THE TROPICAL STORM WATCH FOR THE BIG ISLAND…AND THE ISSUANCE OF
A TROPICAL STORM WATCH FOR MAUI COUNTY AT THIS TIME.
FORECAST POSITIONS AND MAX WINDS

INIT 30/0300Z 17.0N 147.6W 120 KT 140 MPH
12H 30/1200Z 17.9N 148.7W 115 KT 135 MPH
24H 31/0000Z 19.0N 150.0W 110 KT 125 MPH
36H 31/1200Z 20.0N 151.5W 95 KT 110 MPH
48H 01/0000Z 21.0N 153.0W 80 KT 90 MPH
72H 02/0000Z 23.0N 156.0W 70 KT 80 MPH
96H 03/0000Z 25.0N 159.0W 60 KT 70 MPH
120H 04/0000Z 27.0N 162.0W 55 KT 65 MPH

$$
FORECASTER R BALLARD