WTPS31 PGTW 012100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 18P (JOSIE) WARNING NR 006 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 011800Z --- NEAR 19.7S 177.8E MOVEMENT PAST SIX HOURS - 060 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 19.7S 177.8E --- FORECASTS: 12 HRS, VALID AT: 020600Z --- 20.2S 178.8E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 210 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 160 DEG/ 09 KTS --- 24 HRS, VALID AT: 021800Z --- 21.9S 179.5E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 200 NM SOUTHEAST QUADRANT 095 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 150 DEG/ 07 KTS --- 36 HRS, VALID AT: 030600Z --- 23.1S 179.8W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 175 NM NORTHEAST QUADRANT 235 NM SOUTHEAST QUADRANT 135 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 150 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 031800Z --- 24.2S 179.1W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 320 NM SOUTHEAST QUADRANT 175 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 07 KTS --- 72 HRS, VALID AT: 041800Z --- 26.3S 177.0W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 365 NM SOUTHEAST QUADRANT 210 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT --- REMARKS: 012100Z POSITION NEAR 19.8S 178.1E. TROPICAL CYCLONE 18P (JOSIE), LOCATED APPROXIMATELY 102 NM SOUTH- SOUTHWEST OF SUVA, FIJI, HAS TRACKED EAST-NORTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) IMAGERY DEPICTS AN INCREASINGLY ASYMMETRIC CENTRAL DENSE OVERCAST BEING SHEARED TO THE EAST, OBSCURING A LOW LEVEL CIRCULATION CENTER (LLCC). A 011732Z SSMIS 91 GHZ IMAGE REVEALS LOW-LEVEL BANDING FEATURES TO THE WEST OF FLARING DEEP CONVECTION TO THE EAST. THE INITIAL POSITION IS BASED ON THE AFOREMENTIONED SSMIS IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS SET AT 35 KNOTS, WHICH IS IN AGREEMENT WITH THE PHFO AND KNES DVORAK CURRENT INTENSITY ESTIMATES OF T2.5 (35 KTS), AND SLIGHTLY ABOVE THE PGTW ESTIMATE OF T2.0 (30 KTS). ENVIRONMENTAL ANALYSIS INDICATES THAT A SHORTWAVE TROUGH ALOFT IS IMPINGING ON THE WESTWARD OUTFLOW AND PROVIDING HIGH (25-40 KNOT) VERTICAL WIND SHEAR (VWS). DRY AIR IS BEGINNING TO WRAP INTO THE SYSTEM, CONTRIBUTING TO THE RECENT WEAKENING. HOWEVER, ROBUST BUT DIMINISHING OUTFLOW TO THE EAST IS PARTIALLY COMPENSATING AND STILL SUPPORTING SOME CONVECTION ON THE EASTERN SIDE OF THE SYSTEM. SEA SURFACE TEMPERATURES ARE A FAVORABLE 28 DEGREES CELSIUS, DECREASING TO THE SOUTH. AN AMSU CROSS-SECTION REVEALS A BURGEONING MID-TROPOSPHERIC COLD ANOMALY SANDWICHED BETWEEN LOW-LEVEL AND UPPER- LEVEL WARM ANOMALIES, WHICH IS SOMEWHAT CHARACTERISTIC OF A SUBTROPICAL SYSTEM. TC 18P RECENTLY MADE A SLIGHT TRACK DEVIATION TOWARD THE NORTHEAST UNDER THE STEERING INFLUENCE OF A SUB-TROPICAL RIDGE THAT IS RECEDING TO THE EAST, BUT A TURN BACK TOWARD THE SOUTHEAST IS EXPECTED. THE JTWC INTENSITY FORECAST PREDICTS THAT THE SYSTEM WILL MAINTAIN A MARGINAL 35-KT INTENSITY AS THE UPPER LEVEL TROUGH SUPPRESSES DIVERGENCE ALOFT AND VWS INCREASES ALONG THE FORECAST TRACK DUE TO A MID-LATITUDE JET TO THE SOUTH. GLOBAL MODELS ARE IN AGREEMENT THAT TC 18P WILL CONTINUE TO TRACK EAST THEN SOUTHEASTWARD. THE TRANSITION SCENARIO TO SUBTROPICAL STORM AFTER TAU 48 NOW APPEARS TO BE FAVORED BY NUMERICAL MODEL GUIDANCE AS AN UPPER-LEVEL LOW DEVELOPS OVER THE SYSTEM AND THERMAL ADVECTION BECOMES MORE PRONOUNCED, RESULTING IN AN EXPANDED WIND FIELD. THE FLORIDA STATE UNIVERSITY CYCLONE PHASE SPACE PREDICTS THE SYSTEM WILL REMAIN WARM CORE BUT BECOME MORE ASYMMETRIC, WHICH SUGGESTS A MORE SUBTROPICAL VICE EXTRATROPICAL TRANSITION. SLIGHT INTENSIFICATION TOWARD THE LATTER PORTION OF THE FORECAST DURING SUBTROPICAL TRANSITION IS EXPECTED THROUGH TAU 72. DUE TO LOW SPREAD IN THE MULTI-MODEL CONSENSUS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 011800Z IS 20 FEET. NEXT WARNINGS AT 020300Z, 020900Z, 021500Z AND 022100Z.//