WTPA44 PHFO 060232 TCDCP4 TROPICAL STORM JIMENA DISCUSSION NUMBER 42 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015 500 PM HST SAT SEP 05 2015 JIMENA HAS DETERIORATED FURTHER SINCE THIS MORNING AND DEEP CONVECTION IN RECENT IMAGES HAS BEEN LIMITED TO A PRIMARY RAIN BAND IN THE NORTHWESTERN SEMICIRCLE. ALTHOUGH THE LOW LEVEL CENTER REMAINS OBSCURED...THE CURVATURE OF NUMEROUS LOW LEVEL CLOUD LINES PROVIDES A REASONABLE APPROXIMATION OF ITS LOCATION AND CENTER POSITIONS FROM THE FIX AGENCIES WERE CLUSTERED FAIRLY WELL. DVORAK INTENSITY ESTIMATES CAME IN AT 3.5/55 KT FROM PHFO AND SAB...AND 4.0/65 KT FROM JTWC. THE UW/CIMSS ADT ESTIMATE FROM 0000 UTC WAS 45 KT. AN AVERAGE OF THESE ESTIMATES...55 KT...WAS USED FOR THE INITIAL INTENSITY OF THIS ADVISORY. A 1943 UTC ASCAT PASS WAS USED TO EXPAND THE WIND RADII ALONG THE EASTERN SIDE OF THE CIRCULATION A BIT WHILE TRYING TO FACTOR IN THE OVERALL WEAKENING SINCE THE OBSERVATION TIME. A LARGE MID- AND UPPER LEVEL TROUGH WEST OF THE MAIN HAWAIIAN ISLANDS CONTINUES TO PRODUCE WEST-SOUTHWESTERLY VERTICAL WIND SHEAR ACROSS JIMENA. THIS WIND SHEAR...WHICH WAS 24 KT IN THE 0000 UTC UW/CIMSS ANALYSIS...IS EXPECTED TO CONTINUE AT THESE LEVELS OVER THE NEXT 24 HOURS THEN SHIFT TO THE WEST-NORTHWEST AND SLOWLY STRENGTHEN TO MORE THAN 30 KT AFTER 96 HOURS. SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK SHOULD REMAIN CLOSE TO 26.5C...WHICH IS BARELY ADEQUATE. GIVEN THE CURRENT DECLINING STATE OF JIMENA AND THE POOR UPCOMING ENVIRONMENTAL FACTORS...IT APPEARS THAT SHIPS IS HANDLING THE SITUATION BETTER THAN THE OTHER INTENSITY MODELS SUCH AS THE HWRF AND GFDL. THUS...THE INTENSITY FORECAST HAS BEEN ADJUSTED TOWARDS THE SHIPS GUIDANCE BUT IS CONSERVATIVE IN THAT IT MAINTAINS A VIABLE TROPICAL CYCLONE THROUGH THE FORECAST PERIOD WHEREAS SHIPS DISSIPATES JIMENA AFTER 60 HOURS. NATURALLY...IF THE CONDITION OF JIMENA CONTINUES TO DECLINE...SUBSEQUENT FORECASTS WILL NEED TO REFLECT A QUICKER PATH TO POST-TROPICAL/REMNANT LOW STATUS. JIMENA HAS BEEN MOVING BETWEEN THE ABOVE-MENTIONED MID- AND UPPER-LEVEL TROUGH TO THE WEST OF THE MAIN HAWAIIAN ISLANDS AND A RIDGE TO THE NORTH AND EAST. THE GLOBAL MODELS STRENGTHEN THE RIDGE TO THE NORTH...THEN DEVELOP AN ANTICYCLONE TO THE NORTHWEST OF JIMENA AFTER 72 HOURS. THIS WILL RESULT IN A GENERAL WESTWARD TURN...WITH THE AMOUNT OF TURN VARYING AMONG THE DIFFERENT MODELS. THE CURRENT FORECAST HAS BEEN ALIGNED CLOSE TO THE PREVIOUS FORECAST AND CLOSE TO THE ECMWF FORECAST TRACK ON THE SOUTH SIDE OF THE GUIDANCE ENVELOPE. NOTE THAT EVEN IF JIMENA LOSES MOST OF ITS DEEP CONVECTION AND BECOMES A SHALLOW SYSTEM...THE BAM-SHALLOW FORECAST IS STILL RELATIVELY CLOSE TO THE DYNAMICAL CONSENSUS AND KEEPS JIMENA WELL NORTH OF THE MAIN HAWAIIAN ISLANDS. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 22.5N 147.2W 55 KT 65 MPH 12H 06/1200Z 23.4N 147.9W 50 KT 60 MPH 24H 07/0000Z 24.4N 148.9W 45 KT 50 MPH 36H 07/1200Z 25.0N 150.0W 40 KT 45 MPH 48H 08/0000Z 25.4N 151.2W 35 KT 40 MPH 72H 09/0000Z 25.0N 154.4W 30 KT 35 MPH 96H 10/0000Z 25.0N 157.5W 30 KT 35 MPH 120H 11/0000Z 25.0N 161.0W 25 KT 30 MPH $$ FORECASTER KODAMA