WTPA33 PHFO 310249
TCPCP3

BULLETIN
HURRICANE IGNACIO ADVISORY NUMBER 25
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
500 PM HST SUN AUG 30 2015

…IGNACIO STILL A MAJOR HURRICANE 350 MILES EAST OF THE BIG ISLAND
AND TRACKING NORTHWEST…

SUMMARY OF 500 PM HST…0300 UTC…INFORMATION
———————————————-
LOCATION…19.8N 149.6W
ABOUT 355 MI…575 KM E OF HILO HAWAII
ABOUT 545 MI…880 KM E OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…115 MPH…185 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 12 MPH…19 KM/H
MINIMUM CENTRAL PRESSURE…961 MB…28.38 INCHES

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

THE TROPICAL STORM WATCH FOR MAUI COUNTY AND THE BIG ISLAND HAS
BEEN DISCONTINUED.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

NONE.

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

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 500 PM HST…0300 UTC…THE EYE OF HURRICANE IGNACIO WAS LOCATED
NEAR LATITUDE 19.8 NORTH…LONGITUDE 149.6 WEST. IGNACIO IS MOVING
TOWARD THE NORTHWEST NEAR 12 MPH…19 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 APPROXIMATELY 200
MILES NORTHEAST OF THE BIG ISLAND AND MAUI MONDAY AND TUESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 115 MPH…185 KM/H…WITH HIGHER
GUSTS. IGNACIO IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. RAPID WEAKENING IS EXPECTED…AND IGNACIO MAY
BE A TROPICAL STORM BY TUESDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES…45 KM…FROM
THE CENTER…AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 160
MILES…260 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 961 MB…28.38 INCHES.

HAZARDS AFFECTING LAND
———————-
SURF…LARGE SWELLS GENERATED BY IGNACIO WILL CONTINUE TO BUILD
ALONG EAST AND SOUTHEAST FACING SHORES OF THE MAIN HAWAIIAN ISLANDS
OVER THE NEXT COUPLE OF DAYS. RESULTANT SURF WILL BE LARGE AND
POTENTIALLY LIFE-THREATENING…ESPECIALLY ON THE BIG ISLAND AND
MAUI.

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

$$
FORECASTER R BALLARD

WTPA43 PHFO 310318
TCDCP3

HURRICANE IGNACIO DISCUSSION NUMBER 25
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
500 PM HST SUN AUG 30 2015

THE LAST RECONNAISSANCE PASS THROUGH THE EYE OF IGNACIO MAINTAINED A
SURFACE PRESSURE OF 961 MB. ALTHOUGH THE MAXIMUM FLIGHT LEVEL WIND
WAS 99 KNOTS…THE SFMR PICKED UP WINDS OF 106 KT ON THE LAST PASS
THROUGH THE NORTHEAST QUADRANT. THE INTENSITY WILL BE KEPT TO 100 KT
FOR THIS ADVISORY. HOWEVER…SHEAR IS DEFINITELY STARTING TO TAKE A
TOLL ON IGNACIO AS THE SATELLITE AND MICROWAVE PRESENTATION
CONTINUES TO SLOWLY DEGRADE AS THE EYE BECOMES CLOUD-FILLED AND
INDISTINCT…THE EYEWALL IS OPEN AND DETERIORATING…AND SHEAR IS
RESTRICTING OUTFLOW IN THE SOUTHWEST QUADRANT.

THE INITIAL MOTION IS 325/10. THE HURRICANE WILL CONTINUE TO TRACK
TOWARD THE NORTHWEST…GENERALLY TOWARD A WEAK BUT DIGGING UPPER
LEVEL TROUGH NEAR THE MAIN HAWAIIAN ISLANDS. THE TRACK GUIDANCE
REMAINS FAIRLY TIGHTLY CLUSTERED. THE SLIGHTLY MORE NORTHWARD
MOTION OVER THE PAST 24 HOURS HAS CARRIED IGNACIO A LITTLE FARTHER
AWAY THAN FIRST EXPECTED…AND THUS WE ARE DISCONTINUING THE
TROPICAL STORM WATCH FOR MAUI COUNTY AND THE BIG ISLAND AT THIS
TIME. A SLIGHT BEND BACK TOWARD THE NORTHWEST IS STILL EXPECTED
AFTER 24 HOURS AS IGNACIO BECOMES INCREASINGLY SHEARED. A STRONGER
DIGGING MID-LATITUDE TROUGH WILL LIKELY PICK UP IGNACIO LATE IN THE
FORECAST PERIOD…PULLING IT NORTHWARD INTO THE MID-LATITUDES. OUR
FORECAST FOLLOWS CONSENSUS CLOSELY FOR THE FIRST 48 HOURS…THEN
TRENDS SLIGHTLY TO THE WEST OF THE CONSENSUS IN THE DAYS 3-5 TIME
FRAME ASSUMING A SYSTEM WEAKER THAN THE DYNAMICAL MODELS SUGGEST.

THE UW-CIMSS SHEAR ANALYSIS SHOWS 20-25 KNOTS OF SHEAR NOW
IMPACTING IGNACIO…AND THE SHEAR INCREASES EVEN MORE ALONG THE
FORECAST TRACK…SO IGNACIO/S HOURS AS A HURRICANE…MUCH LESS A
MAJOR ONE…ARE NUMBERED. THE INTENSITY FORECAST HAS NOT CHANGED…
SHOWING RAPID WEAKENING IN THE NEXT 48 HOURS WITH A MORE GRADUAL
WEAKENING EXPECTED THEREAFTER AS IGNACIO BECOMES A MORE SHALLOW
SYSTEM. THERE IS SOME INDICATION IN THE GLOBAL MODELS THAT THE SHEAR
MIGHT TEMPORARILY WEAKEN IN THE LONGER TIME RANGES…BUT BY THEN
IGNACIO WILL BE MOVING OVER THE SUB-27C SEA SURFACE TEMPERATURES AS
IT APPROACHES AND CROSSES LATITUDE 30N.
FORECAST POSITIONS AND MAX WINDS

INIT 31/0300Z 19.8N 149.6W 100 KT 115 MPH
12H 31/1200Z 20.8N 150.5W 85 KT 100 MPH
24H 01/0000Z 21.9N 151.8W 70 KT 80 MPH
36H 01/1200Z 23.0N 153.2W 60 KT 70 MPH
48H 02/0000Z 24.0N 154.6W 55 KT 65 MPH
72H 03/0000Z 25.9N 157.8W 50 KT 60 MPH
96H 04/0000Z 28.1N 161.4W 45 KT 50 MPH
120H 05/0000Z 32.0N 163.6W 45 KT 50 MPH

$$
FORECASTER R BALLARD