WDPS31 PGTW 210300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 26P (GINA) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.9S 169.4E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 27 NM NORTHWEST OF ANEITYUM, VANUATU MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL (MSI) SATELLITE IMAGERY DEPICTS FLARING CONVECTION WITH A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). CONVECTION CONTINUES TO BE SHEARED TOWARD THE SOUTH AS THE SYSTEM INTERACTS WITH A BROAD UPPER-LEVEL TROUGH TO THE WEST. ADDITIONALLY, THE SYSTEM IS STILL SEEMINGLY MAINTAINING INTENSITY AS IT REMAINS OVER WARM SEA SURFACE TEMPERATURES OF 26-27 DEGREES CELSIUS. CONTRARY TO THE PREVIOUSLY EXPECTED SHORT-TERM MOTION, 26P HAS CONTINUED TO TRACK EAST-SOUTHEASTWARD DURING THE PAST SIX HOURS, TOWARD THE ISLAND OF ANEITYUM, VANUATU. THE INITIAL POSITION IS NOW PLACED ROUGHLY 70 NM EAST OF THE PRIOR FORECAST TRACK WITH MEDIUM CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC IN THE ANIMATED SHORTWAVE IR IMAGERY. THE INITIAL INTENSITY IS HELD AT 35 KNOTS AS A BLEND OF DVORAK ESTIMATES OF T2.0 (30 KNOTS) TO T2.5 (35 KNOTS), AN ADT ESTIMATE OF 27 KNOTS, AND A 201846Z SMAP PASS THAT SHOWED 40-45 KNOT WINDS SEVERAL HOURS AGO. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS KNES: T2.5 - 35 KTS PHFO: T2.0 - 30 KTS CIMSS SATCON: 37 KTS AT 202204Z CIMSS ADT: 27 KTS AT 202340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 30+ KTS SST: 26-27 CELSIUS OUTFLOW: MODERATE POLEWARD OTHER FACTORS: DEEP DRY AIR TO THE NORTHWEST ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: DUE TO THE CONTINUING EASTWARD COMPONENT TO 26P'S CURRENT MOTION, THE INITIAL POSITION AND TRACK HAVE BEEN FURTHER SHIFTED ABOUT 70 NM TO THE EAST FORECAST DISCUSSION: 26P (GINA) HAS CONTINUED TO TRACK FARTHER EAST OF THE PRIOR FORECAST TRACK AS WELL AS MODEL GUIDANCE, LIKELY DUE TO CONTINUING CONVECTIVE ACTIVITY SOUTH OF THE LOW-LEVEL CIRCULATION CENTER (LLCC) THAT HAS APPARENTLY TUGGED THE LLCC FARTHER EAST THAN MODELS ANTICIPATED. DEVELOPMENT CONTINUES TO BE INHIBITED BY STRONG NORTHWESTERLY VERTICAL WIND SHEAR OF ABOUT 30 KNOTS WHICH IS CONTINUING TO CONFINE CONVECTION ENTIRELY TO THE SOUTHERN SEMICIRCLE. WITHIN THE NEXT 24 HOURS, VERTICAL WIND SHEAR IS FORECAST TO INCREASE TO 45-50 KNOTS, ALONG WITH DEEP-LAYER DRY AIR BEING ADVECTED OVER THE CIRCULATION, RESULTING IN A DECREASE IN INTENSITY TO BELOW WARNING CRITERIA. THE TRACK FORECAST REMAINS SOMEWHAT PROBLEMATIC DUE TO THE SIGNIFICANT DEVIATION OF THE CURRENT MOTION EAST OF PREVIOUS MODEL GUIDANCE. HOWEVER, DYNAMICAL MODELS INSIST THAT 26P WILL BECOME FULLY DECOUPLED FROM THE CONVECTION IMMINENTLY, WHICH SHOULD RESULT IN A SLIGHT TURN BACK TOWARD THE SOUTH AND SOUTHWEST AS THE ORPHANED LLCC BEGINS TO BE STEERED MORE BY THE LOW-LEVEL EASTERLY FLOW. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE HAS CONTINUED TO INITIALIZE FARTHER EAST AND HAS COME INTO BETTER AGREEMENT ON A SOUTH-SOUTHEASTWARD TRACK AT TAU 12 BEFORE TURNING SOUTHWESTWARD BY TAU 24. THUS THE JTWC FORECAST TRACK IS PLACED CLOSE TO THE MULTI MODEL CONSENSUS. THE INTENSITY FORECAST REMAINS UNCHANGED BY MAINTAINING 35 KNOTS BY TAU 12 BEFORE DOWNGRADING BELOW WARNING CRITERIA BY TAU 24. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: HIGH// NNNN