WTPA44 PHFO 061455

TCDCP4



TROPICAL STORM JIMENA DISCUSSION NUMBER  44

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP132015

500 AM HST SUN SEP 06 2015



JIMENA IS EXHIBITING THE SATELLITE SIGNATURE OF A TROPICAL CYCLONE

THAT IS FEELING THE DEBILITATING EFFECTS OF PERSISTENT AND

RELATIVELY STRONG SOUTHWESTERLY SHEAR. INFRARED IMAGERY SHOWS CURVED

CLOUD BANDS OF RELATIVELY WEAK CONVECTION FORMING NORTH AND EAST OF

THE ASSUMED LOW LEVEL CIRCULATION CENTER...WHILE WATER VAPOR IMAGERY

SHOWS DRY AIR BEING ENTRAINED INTO THE CIRCULATION WITH THE

SOUTHWEST FLOW ALOFT. LATEST SUBJECTIVE CURRENT INTENSITY ESTIMATES

FROM PHFO/SAB/PGTW WERE 3.0/45 KT ACROSS THE BOARD...WHILE LATEST

UW-CIMSS ADT COMPUTATION YIELDED 3.1/47 KT. A 0730Z ASCAT PASS

HOWEVER INDICATED WINDS AS HIGH AS 55 KT IN THE WESTERN SEMICIRCLE.

AVERAGING THIS DATA SUPPORTS MAINTAINING THE INITIAL INTENSITY AT

50 KT FOR THIS ADVISORY.



THE FORECAST TRACK PHILOSOPHY IS ESSENTIALLY UNCHANGED...AND

THUS THE UPDATED OFFICIAL TRACK FORECAST OFFERS LITTLE CHANGE.

JIMENA IS TRACKING NORTHWEST...325/08 KT...TOWARD A WEAKNESS IN THE

MID-LEVEL RIDGE...BROUGHT ABOUT BY DEEP TROUGHING TO THE NORTHWEST

OF THE MAIN HAWAIIAN ISLANDS. MID-LEVEL RIDGING CURRENTLY PREVAILS

FROM NORTH THROUGH EAST THROUGH SOUTHEAST OF THE CYCLONE...BUT THIS

LARGE-SCALE PATTERN IS FORECAST TO CHANGE OVER THE NEXT DAY OR TWO.

MID-LEVEL HEIGHTS NEAR AND NORTHWEST OF HAWAII ARE EXPECTED TO

STEADILY INCREASE AS THE CURRENT TROUGH WEAKENS AND MOVES SOUTHWEST.

THIS ALLOWS RIDGING TO BUILD NORTH AND WEST OF JIMENA...RESULTING

IN A TURN TOWARD THE WEST BY DAY 2 THAT IS FORECAST TO PERSIST

THROUGH THE END OF THE FORECAST PERIOD. THE RELIABLE DYNAMICAL

MODEL GUIDANCE ENVELOPE IS RELATIVELY SMALL THROUGH ABOUT 48

HOURS...BUT SHOWS INCREASING SPREAD THEREAFTER DUE TO DIFFERENCES

IN THE WAY THE MODELS HANDLE THE EVOLUTION OF THE BUILDING RIDGE.

THE OFFICIAL FORECAST TRACK IS VERY CLOSE TO THE GUIDANCE SUPPLIED

BY THE GFS ENSEMBLE MEAN AND THE FLORIDA STATE SUPER ENSEMBLE.



PERSISTENT WESTERLY TO NORTHWESTERLY SHEAR IS EXPECTED TO BE BETWEEN

20 TO 30 KT THROUGH THE BULK OF THE FORECAST PERIOD...LEADING TO

STEADY WEAKENING...AND THE EVENTUAL DEMISE OF JIMENA. THE OFFICIAL

INTENSITY FORECAST MOST CLOSELY RESEMBLES LGEM GUIDANCE...AND

ANTICIPATES THAT JIMENA WILL BECOME A POST-TROPICAL REMNANT LOW BY

DAY 4. THIS IS A LITTLE LESS AGGRESSIVE IN WEAKENING JIMENA THAN

SHIPS GUIDANCE...WHICH ANTICIPATES DISSIPATION BY DAY 3.





FORECAST POSITIONS AND MAX WINDS



INIT  06/1500Z 24.0N 148.1W   50 KT  60 MPH

 12H  07/0000Z 25.0N 148.9W   45 KT  50 MPH

 24H  07/1200Z 25.8N 150.2W   40 KT  45 MPH

 36H  08/0000Z 26.2N 151.5W   35 KT  40 MPH

 48H  08/1200Z 26.2N 152.9W   30 KT  35 MPH

 72H  09/1200Z 26.0N 156.5W   30 KT  35 MPH

 96H  10/1200Z 26.0N 159.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

120H  11/1200Z 26.0N 162.0W   25 KT  30 MPH...POST-TROP/REMNT LOW



$$



FORECASTER BIRCHARD