WTPA44 PHFO 041454 TCDCP4 HURRICANE JIMENA DISCUSSION NUMBER 36 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015 500 AM HST FRI SEP 04 2015 JIMENA CONTINUES TO STRUGGLE IN AN INCREASINGLY HOSTILE ENVIRONMENT EARLY THIS MORNING. THERE IS NO EYE EVIDENT...AND DEEP CONVECTION IS CONFINED PRIMARILY IN A RELATIVELY SMALL AREA IN THE NORTHEASTERN SEMICIRCLE OF THE INNER CORE OF THE HURRICANE ACCORDING TO 1150Z AMSU IMAGERY. THE LATEST ESTIMATE OF ENVIRONMENTAL VERTICAL WIND SHEAR IN THE VICINITY OF JIMENA ACCORDING TO UW-CIMSS IS 16 KT FROM 245 DEGREES AND 12 KT FROM 285 DEGREES BASED ON THE SHIPS GUIDANCE. IN ADDITION TO SHEAR BEING A LIKELY CULPRIT IN THE DEGRADATION OF JIMENA...WATER VAPOR IMAGERY STRONGLY SUGGESTS THAT VERY DRY IS BEING ENTRAINED INTO THE SYSTEM. ALSO...EVEN THOUGH THE OUTFLOW ALOFT WAS RATHER IMPRESSIVE EARLIER TONIGHT...IT NOW APPEARS TO BE SHOWING SOME RESTRICTIONS IN THE WESTERN QUADRANT. THE MOST RECENT SUBJECTIVE DVORAK ESTIMATES OF CURRENT INTENSITY WERE 4.5/77 KT FROM PHFO AND JTWC...AND 4.0/65 KT FROM SAB. THE LATEST UW-CIMSS ADT INTENSITY ESTIMATE IS 4.3/72 KT. BASED ON A BLEND OF THESE INTENSITY ESTIMATES...WE HAVE LOWERED THE INITIAL INTENSITY TO 75 KT. JIMENA REMAINS IN AN AREA OF WEAK STEERING...AND THE CURRENT MOTION IS 310/04 KT. THERE IS A MID LEVEL ANTICYCLONE TO THE EAST-SOUTHEAST OF JIMENA NEAR 16N 135W. THERE IS ALSO MID LEVEL RIDGE EXTENDING FROM ANOTHER ANTICYCLONE NEAR 36N 155W DOWN TO 22N 153W. SINCE... JIMENA IS SANDWICHED BETWEEN THESE FEATURES...IT APPEARS THAT BETA-DRIFT MAY BE ONE OF THE PRIMARY STEERING MECHANISMS. THIS WEAK STEERING WILL LIKELY CONTINUE THROUGH TONIGHT. FROM SATURDAY INTO SUNDAY...THE WEAK STEERING PATTERN WILL PERSIST AS A MID LEVEL RIDGE TO THE EAST BUILDS TO THE SOUTHEAST AND SOUTH OF JIMENA. THIS IS EXPECTED TO RESULT IN A SLIGHTLY FASTER MOTION TOWARD THE NORTH-NORTHWEST. BY MONDAY AND TUESDAY...THE MID LEVEL RIDGING TO THE NORTH IS FORECAST TO STRENGTHEN...AND JIMENA WILL LIKELY TURN TOWARD THE WEST. THE LATEST FORECAST IS CLOSE TO THE PREVIOUS THROUGH 72 HOURS. THE FORECAST TRACK IS NUDGED SLIGHTLY TO THE RIGHT COMPARED WITH THE PREVIOUS FORECAST ON DAYS 4 AND 5. THIS FORECAST TRACK IS VERY CLOSE TO A BLEND BETWEEN THE TVCN AND GFEX CONSENSUS GUIDANCE THROUGH DAY 4...AND THE GFEX ON DAY 5. NOTE THAT THE MODEL SPREAD IS FAIRLY SMALL THROUGH 72 HOURS...WITH A MUCH WIDER SPREAD ON DAYS 4 AND 5. THEREFORE...THERE REMAINS A GREAT DEAL OF UNCERTAINTY IN THE TRACK FORECAST AS THIS SYSTEM MOVES TO A POSITION NORTH-NORTHEAST OF THE MAIN HAWAIIAN ISLANDS. THE LATEST INTENSITY FORECAST CONTINUES TO SHOW GRADUAL...BUT STEADY WEAKENING. THIS IS PRIMARILY DUE TO THE EFFECTS OF MODERATE WEST-SOUTHWEST TO WEST SHEAR DURING THE NEXT 18-24 HOURS. BEYOND 24 HOURS...THE SHEAR STEADILY INCREASES...WHILE SEA SURFACE TEMPERATURES AND OCEAN HEAT CONTENT VALUES GRADUALLY DECREASE. THE LATEST INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS...AND VERY CLOSE TO THE IVCN CONSENSUS...BUT CONTINUES TO SHOW LESS WEAKENING THAN THE LATEST SHIPS GUIDANCE. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 19.7N 145.1W 75 KT 85 MPH 12H 05/0000Z 20.2N 145.4W 70 KT 80 MPH 24H 05/1200Z 20.9N 145.8W 65 KT 75 MPH 36H 06/0000Z 22.0N 146.3W 60 KT 70 MPH 48H 06/1200Z 23.2N 147.1W 55 KT 65 MPH 72H 07/1200Z 24.9N 149.2W 50 KT 60 MPH 96H 08/1200Z 25.0N 151.0W 45 KT 50 MPH 120H 09/1200Z 25.0N 152.5W 35 KT 40 MPH $$ FORECASTER HOUSTON