WTPA43 PHFO 311503

TCDCP3



HURRICANE IGNACIO DISCUSSION NUMBER  27

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP122015

500 AM HST MON AUG 31 2015



THE APPEARANCE OF IGNACIO IN INFRARED SATELLITE IMAGERY CONTINUES

TO DEGRADE FROM AN OBSERVED PEAK THAT OCCURRED ABOUT 24 TO 36 HOURS

AGO. HOWEVER...OVERNIGHT OBSERVATIONS FROM A 53RD WEATHER

RECONNAISSANCE SQUADRON AIRCRAFT INDICATED THAT WINDS AND PRESSURE

ASSOCIATED WITH THE HURRICANE HAVE THUS FAR BEEN FAIRLY SLOW TO

RESPOND. THE ADJUSTED CENTRAL PRESSURE WAS OBSERVED TO BE 964 MB

AROUND 1100Z...WHILE MAX FLIGHT LEVEL WINDS WERE 111 KT...ALTHOUGH

THIS MAX WAS OBSERVED CLOSER TO 0900Z. MAXIMUM SFMR WINDS WERE

CLOSER TO 80 KT...WHILE EVALUATION OF THE LAST EYEWALL DROPSONDE AS

THE AIRCRAFT DEPARTED IGNACIO YIELDS A SURFACE WIND ESTIMATE NEAR

80 KT AS WELL. A BLEND OF THE AIRCRAFT OBSERVATIONS...WITH AN

EMPHASIS ON THE MORE RECENT DATA...SUPPORTS LOWERING THE INITIAL

INTENSITY TO 90 KT FOR THIS ADVISORY.



THE INITIAL MOTION VECTOR FOR THIS ADVISORY IS 320/9 KT...AS

IGNACIO CONTINUES ON A STEADY TRAJECTORY TOWARD THE NORTHWEST.

THE HURRICANE IS MOVING TOWARD A WEAKNESS IN THE MID-LEVEL RIDGE...AS

MID-LEVEL HIGHS ARE CURRENTLY CENTERED TO THE DISTANT EAST-NORTHEAST

OF IGNACIO...AND FAR NORTH OF THE HAWAIIAN ISLANDS. OVER THE NEXT

COUPLE OF DAYS THE HIGH TO THE NORTH WILL BECOME THE PRIMARY

STEERING MECHANISM...WITH ITS ASSOCIATED RIDGE GRADUALLY BUILDING TO

THE NORTHEAST...AND THEN EAST...OF THE SYSTEM. WITH LITTLE CHANGE IN

THE ONGOING FORECAST PHILOSOPHY...THE UPDATED TRACK FORECAST OFFERS

LITTLE IN THE WAY OF SIGNIFICANT CHANGES...AND IS VERY CLOSE TO THE

PREVIOUS FORECAST...AND THE TVCN CONSENSUS.



IGNACIO HAS RAPIDLY WEAKENED OVER THE LAST DAY OR SO...PRIMARILY

DUE TO THE IMPACTS OF INCREASED SOUTHWESTERLY SHEAR...CURRENTLY

BETWEEN 25 AND 30 KT...ACCORDING TO SHIPS AND UW-CIMSS OBJECTIVE

ANALYSES. WITH SHEAR VALUES REMAINING RELATIVELY HIGH THROUGH THE

NEXT 48 HOURS...CONTINUED WEAKENING IS ANTICIPATED. WITH THE SHEAR

EXPECTED TO DIMINISH SOMEWHAT AFTERWARD...THE FORECAST ANTICIPATES

LITTLE CHANGE IN THE INTENSITY OF THEN TROPICAL STORM IGNACIO FROM

DAYS 2 THROUGH 4...DESPITE GRADUALLY DIMINISHING WATER TEMPERATURES

ALONG THE FORECAST TRACK. SHEAR IS EXPECTED TO INCREASE AGAIN ON DAY

5...LEADING TO FURTHER WEAKENING. THE INTENSITY FORECAST CLOSELY

FOLLOWS TRENDS PRESENTED BY SHIPS AND THE INTENSITY CONSENSUS

IVCN.



WITH IGNACIO NOW CONSIDERED TO BE A DIMINISHED THREAT TO THE MAIN

HAWAIIAN ISLANDS...A RECONNAISSANCE FLIGHT INTO IGNACIO LATER THIS

MORNING IS EXPECTED TO BE THE LAST. THE CENTRAL PACIFIC HURRICANE

CENTER IS EXTREMELY GRATEFUL FOR THE EFFORTS OF U.S. AIR FORCE

RESERVISTS IN PROVIDING CRITICAL REAL-TIME DATA...AND TO THE

CHIEF...AERIAL RECONNAISSANCE COORDINATION ALL HURRICANES

/CARCAH/...FOR THEIR PATIENCE AND PROFESSIONALISM IN HELPING TO

COORDINATE OUR SURVEILLANCE REQUIREMENTS.





FORECAST POSITIONS AND MAX WINDS



INIT  31/1500Z 20.9N 150.8W   90 KT 105 MPH

 12H  01/0000Z 21.9N 151.8W   80 KT  90 MPH

 24H  01/1200Z 22.9N 153.3W   70 KT  80 MPH

 36H  02/0000Z 23.9N 154.7W   65 KT  75 MPH

 48H  02/1200Z 24.9N 156.4W   60 KT  70 MPH

 72H  03/1200Z 27.1N 159.8W   60 KT  70 MPH

 96H  04/1200Z 29.5N 162.5W   60 KT  70 MPH

120H  05/1200Z 33.5N 163.5W   55 KT  65 MPH



$$



FORECASTER BIRCHARD