MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 11W (ELEVEN) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 11W (ELEVEN), LOCATED APPROXIMATELY 272 NM EAST-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED SOUTHWESTWARD AT 12 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS CONVECTIVE BANDING WRAPPING UNDER FLARING DEEP CONVECTION OVERHEAD THE LOW LEVEL CIRCULATION CENTER (LLCC). A 311107Z ASCAT-A IMAGE DEPICTS A SLIGHTLY ELONGATED CIRCULATION WITH A SWATH OF 25-30 KT WINDS DISPLACED WITHIN THE DEEP CONVECTION TO THE SOUTHEAST OF THE LLCC AND WEAKER (15-20 KT) WINDS ELSEWHERE. BASED ON THE AFOREMENTIONED ASCAT IMAGE ALONG WITH DVORAK CURRENT INTENSITY ESTIMATES OF T1.0-2.0 (25-30 KTS) BY PGTW, RJTD, AND KNES, THE INITIAL INTENSITY IS SET AT 25 KTS WITH GOOD CONFIDENCE. ENVIRONMENTAL ANALYSIS REVEALS THAT TD 11W IS SUPPORTED BY ROBUST EQUATORWARD UPPER LEVEL OUTFLOW AND WARM (30-31 CELSIUS) SEA SURFACE TEMPERATURES (SST) THAT ARE BEING OFFSET BY MODERATE (20-25 KT) VERTICAL WIND SHEAR (VWS). OF NOTE, TD 11W IS CURRENTLY TRACKING SOUTHWESTWARD UNDER THE COMBINED STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE WEST AND AN EXTENSION OF THE STR TO THE NORTHEAST. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE FOR THIS SYSTEM AND SETS THE FORECAST PHILOSOPHY. B. IN THE NEAR-TERM, TD 11W WILL TRACK WEST-SOUTHWESTWARD UNDER THE COMBINED STEERING INFLUENCE OF THE STR TO THE WEST AND THE STR EXTENSION. DURING THIS TIME, THE SYSTEM WILL EXPERIENCE FAVORABLE SST AND CONTINUED DIVERGENCE ALOFT, BUT INTENSIFICATION WILL BE LIMITED DUE TO HIGH VWS VALUES. CONSEQUENTLY, TD 11W IS EXPECTED TO GRADUALLY INTENSIFY TO 40 KTS BY TAU 24. AS A MIDLATITUDE SHORTWAVE TROUGH APPROACHES FROM THE WEST, THE STR TO THE WEST WILL BEGIN TO ERODE WHILE THE STR TO THE NORTHEAST WILL BUILD, BECOMING THE PRIMARY STEERING MECHANISM. UNDER ITS INFLUENCE, THE SYSTEM WILL SLOWLY TURN WESTWARD THEN NORTHWESTWARD THROUGH TAU 72 AS IT TRACKS ALONG THE PERIPHERY. VWS VALUES DECREASE AFTER TAU 24 ALLOWING TD 11W TO STEADILY INTENSIFY ALONG THE FORECAST TRACK. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE GFS AND UKMET ENSEMBLE SOLUTIONS AS OUTLIERS TO THE SOUTH AND THE JGSM SOLUTION TO THE NORTH. THE JTWC FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS WITH FAIR CONFIDENCE. ADDITIONALLY, THE ECMWF ENSEMBLE IS IN GOOD AGREEMENT WITH SPREAD SLOWLY INCREASING IN THE LATER TAUS. C. IN THE EXTENDED PERIOD, THE SYSTEM WILL CONTINUE TO TRACK NORTHWARD ALONG THE PERIPHERY OF A STR TO THE EAST. THE SYSTEM WILL STEADILY INTENSIFY TO 85 KTS BY TAU 120 DUE TO CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS OF LOW VWS, WARM SST, AND CONDUCIVE OCEAN HEAT CONTENT VALUES. HOWEVER, NUMERICAL MODEL GUIDANCE DIVERGES THROUGHOUT THE FORECAST PERIOD, INCREASING TO A CROSS TRACK SPREAD OF 228 NM BY TAU 120. THEREFORE, DUE TO THE UNCERTAINTY (LARGE SPREAD) IN THE MODEL SOLUTIONS, THERE IS OVERALL FAIR CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS PLACED ALONG THE MULTI-MODEL CONSENUS.// NNNN NNNN