WTPA43 PHFO 312057

TCDCP3



HURRICANE IGNACIO DISCUSSION NUMBER  28

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP122015

1100 AM HST MON AUG 31 2015



IGNACIO CONTINUES TO FEEL THE EFFECTS OF 25 TO 30 KNOTS OF

SOUTHWESTERLY SHEAR AS ANALYZED BY UW-CIMSS. ALTHOUGH CONVECTION

CONTINUES TO BURST ON THE WEST AND NORTHWEST SIDE OF THE LOW LEVEL

CENTER...DEEP CONVECTIVE CLOUDS ARE GETTING QUICKLY PUSHED TO THE

NORTHEAST...AND MORE AND MORE LOW CLOUD LINES ARE BECOMING EXPOSED

ON THE SOUTH AND SOUTHWEST SIDE. THE SUBJECTIVE INTENSITY ESTIMATES

WERE A CONSENSUS 5.0...WITH THE CIMSS-ADT COMING IN AT 4.9. THUS...

WILL MAINTAIN A 90 KT INITIAL INTENSITY FOR THIS ADVISORY. ONE FINAL

RECONNAISSANCE FLIGHT IS SCHEDULED FOR 0000 UTC.



THE INITIAL MOTION ESTIMATE IS 315/8. THE TRACK FORECAST REMAINS

RELATIVELY STRAIGHTFORWARD...NO PUN INTENDED. THE NORTHWESTWARD

MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 3 DAYS AS IGNACIO HEADS

TOWARD AND THROUGH A WEAKNESS IN A MID-LEVEL RIDGE. AFTER 3 DAYS...

A TURN TOWARD THE NORTH IS EXPECTED AS IGNACIO BEGINS TO GET STEERED

BY A STRONG...DIGGING MID-LATITUDE TROUGH TO THE WEST AND NORTHWEST

OF THE CYCLONE. THIS FORECAST IS MAINLY JUST AN UPDATE TO THE

PREVIOUS...AND IN EXCELLENT AGREEMENT WITH THE TIGHTLY CLUSTERED

GUIDANCE.



THE INTENSITY FORECAST IS MORE PERPLEXING AND HAS A FAIRLY HIGH

AMOUNT OF UNCERTAINTY. THE CURRENT SOUTHWESTERLY SHEAR OVER THE

CYCLONE IS LIKELY TO CONTINUE FOR THE NEXT 24 TO 48 HOURS. ASSUMING

THE TROPICAL CYCLONE CAN MAINTAIN DEEP CONVECTION FOR THAT

LONG...IGNACIO MAY TEMPORARILY ENCOUNTER A ZONE OF REDUCED WIND

SHEAR TO THE NORTH OF A WEAK UPPER TROUGH OVER THE MAIN HAWAIIAN

ISLANDS. THUS...A LEVELLING OFF IN INTENSITY IS EXPECTED AT THAT

TIME. THEN...AS IGNACIO BEGINS TO MOVE FARTHER NORTH OVER COOLER SEA

SURFACE TEMPERATURES AT DAYS 4 AND 5...WHATEVER IS LEFT OF THE

CYCLONE MAY START TO EXPERIENCE EXTRATROPICAL INFLUENCES FROM A

STRONG DIGGING MID-LATITUDE TROUGH TO THE WEST AND NORTHWEST. THE

MODELS CONTINUE TO SHOW A WARM MID-LEVEL PERTURBATION ASSOCIATED

WITH THE CYCLONE EVEN AT THESE LATITUDES...BUT IT IS DIFFICULT TO

IMAGINE IGNACIO LASTING THROUGH HOSTILE CONDITIONS FOR THAT LONG.

NEVERTHELESS...HAVE MAINTAINED IGNACIO AS A STRONG TROPICAL STORM

THROUGH THE END OF THE FORECAST PERIOD...WHICH IS NOT AS STRONG AS

THE GLOBAL MODELS...BUT IN FAIRLY GOOD AGREEMENT WITH THE INTENSITY

CONSENSUS.





FORECAST POSITIONS AND MAX WINDS



INIT  31/2100Z 21.6N 151.5W   90 KT 105 MPH

 12H  01/0600Z 22.4N 152.6W   80 KT  90 MPH

 24H  01/1800Z 23.5N 154.1W   70 KT  80 MPH

 36H  02/0600Z 24.5N 155.7W   65 KT  75 MPH

 48H  02/1800Z 25.6N 157.3W   60 KT  70 MPH

 72H  03/1800Z 27.8N 160.5W   60 KT  70 MPH

 96H  04/1800Z 31.3N 162.9W   60 KT  70 MPH

120H  05/1800Z 36.1N 164.2W   60 KT  70 MPH



$$

FORECAST R BALLARD