WTPA43 PHFO 020853

TCDCP3



TROPICAL STORM IGNACIO DISCUSSION NUMBER  34

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP122015

1100 PM HST TUE SEP 01 2015



DEEP CONVECTION HAS REMAINED CONFINED MAINLY TO THE NORTH AND WEST

OF THE LOW LEVEL CIRCULATION CENTER /LLCC/ DURING THE EVENING...WITH

JUST LAYERED CLOUDS AND LITTLE DEEP CONVECTION SOUTH OF THE LLCC.

WHILE AN INTERMITTENT WARM SPOT NEAR THE LLCC HAS BEEN EVIDENT IN

RECENT INFRARED SATELLITE IMAGERY...SUBJECTIVE DVORAK CURRENT

INTENSITY ESTIMATES CAME IN AT 3.5/55KT FROM ALL THREE AGENCIES...

AND THE INITIAL INTENSITY WILL BE HELD AT 60 KT FOR THIS ADVISORY.



A SERIES OF MICROWAVE IMAGES AND THE 0600Z SUBJECTIVE CENTER

POSITION ESTIMATES SUGGEST THAT IGNACIO SLOWED DOWN SLIGHTLY DURING

THE LATE AFTERNOON AND EARLY EVENING...AND THE INITIAL MOTION

ESTIMATE IS 310/09 KT. IGNACIO IS FORECAST TO CONTINUE MOVING

STEADILY TO THE NORTHWEST DURING THE NEXT 36 TO 48 HOURS...TOWARD A

WEAKNESS IN THE SUBTROPICAL RIDGE TO THE NORTH OF FRENCH FRIGATE

SHOALS. THERE IS NO SIGNIFICANT CHANGE TO THIS PORTION OF THE

FORECAST TRACK...WHICH LIES VERY CLOSE TO THE PREVIOUS TRACK AND THE

TVCN CONSENSUS. BEYOND 48 HOURS...IGNACIO SHOULD ACCELERATE

NORTHWARD AS IT BECOMES EMBEDDED IN DEEP SOUTHERLY FLOW TO THE EAST

OF A LONGWAVE TROUGH. THE RELIABLE TRACK GUIDANCE REMAINS IN GOOD

AGREEMENT DURING THIS TIME...AND THE LATEST ECMWF SHIFTED EASTWARD

INTO MUCH BETTER AGREEMENT WITH THE GFS/TVCN AT DAYS 4 AND 5. THE

NEW FORECAST TRACK HAS BEEN SHIFTED SOMEWHAT TO THE RIGHT OF THE

PREVIOUS TRACK FOR THOSE FORECAST TIMES...BUT STILL LIES ALONG THE

LEFT EDGE OF THE GUIDANCE ENVELOPE AND IS IN CLOSEST AGREEMENT WITH

THE ECMWF.



IGNACIO CONTINUES TO FEEL THE EFFECTS OF MODERATE SOUTHWESTERLY

VERTICAL WIND SHEAR...WITH THE LATEST UW-CIMSS AND SHIPS ANALYSES

INDICATING SHEAR MAGNITUDE NEAR 20 KT. THE CYCLONE MAY HAVE A WINDOW

OF SOMEWHAT LESS HOSTILE CONDITIONS DURING THE NEXT 24 TO 36

HOURS...WHEN SHEAR MAY LESSEN SOMEWHAT AND THE FORECAST TRACK

WILL REMAIN OVER SEA SURFACE TEMPERATURES NEAR 27C. THE NEW

INTENSITY FORECAST WILL MAINTAIN IGNACIO AT 60 KT DURING THIS

TIME...IN REASONABLE AGREEMENT WITH THE LGEM AND ICON CONSENSUS...

BUT BELOW THE SHIPS WHICH BRINGS IGNACIO BACK TO MINIMAL HURRICANE

INTENSITY IN 24 HOURS. A SLOW WEAKENING TREND SHOULD COMMENCE BY 48

HOURS...WHEN IGNACIO WILL BE MOVING NORTHWARD OVER COOLER WATERS.

IGNACIO MAY BEGIN TO UNDERGO EXTRATROPICAL TRANSITION BY THE END OF

THE FORECAST PERIOD AS IT MOVES NORTH OF 40N AND ACROSS INCREASINGLY

COLD WATERS OF THE NORTH PACIFIC. WILL MAINTAIN IGNACIO AS A

TROPICAL SYSTEM THROUGH 120 HOURS FOR THIS FORECAST CYCLE...IN

COORDINATION WITH THE OCEAN PREDICTION CENTER IN WASHINGTON DC.





FORECAST POSITIONS AND MAX WINDS



INIT  02/0900Z 25.2N 156.2W   60 KT  70 MPH

 12H  02/1800Z 25.9N 157.4W   60 KT  70 MPH

 24H  03/0600Z 27.2N 159.6W   60 KT  70 MPH

 36H  03/1800Z 28.4N 161.6W   60 KT  70 MPH

 48H  04/0600Z 29.7N 163.0W   55 KT  65 MPH

 72H  05/0600Z 33.6N 164.2W   50 KT  60 MPH

 96H  06/0600Z 38.5N 165.0W   50 KT  60 MPH

120H  07/0600Z 44.0N 163.5W   50 KT  60 MPH



$$

FORECASTER JACOBSON