MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 12W (TWELVE) WARNING NR 01// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 12W (TWELVE), LOCATED APPROXIMATELY 275 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH- NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES DEEP CONVECTIVE ACTIVITY HAS INCREASED OVER THE PAST SIX HOURS AND BECOME MORE SYMMETRIC. ADDITIONALLY, AS THE CENTRAL DENSE OVERCAST HAS EXPANDED, THE LOW LEVEL CIRCULATION CENTER (LLCC) IS NO LONGER FULLY EXPOSED. A 111837Z SSMI 85 GHZ PASS DEPICTS THE GENERALLY WEAK LLCC STRUCTURE THAT IS DISPLACED APPROXIMATELY 50 NM SW OF THE STRONG CONVERGENT FLOW PRODUCING THE DEEP CONVECTION TO THE NORTHEAST. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A BLEND OF AGENCY FIXES AND THE AFOREMENTIONED SSMIS DATA. THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS, BASED ON AGENCY DVORAK FIXES RANGING FROM T1.0 TO T1.5 (25 KNOTS). THIS INTENSITY IS REPRESENTATIVE OF THE OVERALL SURFACE CHARACTERISTICS OBSERVED IN 111030Z ASCAT-A DATA, WHILE ISOLATED HIGHER WINDS LIKELY EXIST UNDER THE DEEP CONVECTION. OUTFLOW IS CURRENTLY BEING ENHANCED AS IT TAPS INTO THE MIDLATITUDE FLOW TO THE NORTH, HOWEVER, HIGH (20 KNOT) SOUTHWESTERLY VERTICAL WIND SHEAR IS LIMITING THE POTENTIAL FOR SIGNIFICANT DEVELOPMENT. SEA SURFACE TEMPERATURES REMAIN FAVORABLE AT 28 DEGREES C. THE FSU PHASE SPACE PRODUCT INDICATES 12W IS ON THE BORDER BETWEEN SYMMETRIC WARM AND COLD CORE STRUCTURE AS IT TRACKS AROUND THE WESTERN PERIPHERY OF A SUB-TROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST PHILOSOPHY. B. TD TWELVE IS FORECAST TO CONTINUE TO ROUNDING THE STR OVER, AND BECOME FULLY EXTRATROPICAL BY TAU 36 AS IT INTERACTS WITH THE MID-LATITUDE FLOW. THIS ASSESSMENT IS CONSISTENT WITH THE FSU PHASE SPACE. ADDITIONAL INTENSIFICATION SHOULD REMAIN LIMITED DUE TO THE HIGH VWS, ALTHOUGH THE FORECAST INTENSITY IS INCREASED MODESTLY TO 30 KNOTS TO ACCOUNT FOR THE LLCC BECOMING MORE ALIGNED WITH THE CONVECTION. LIMITED INITIAL MODEL GUIDANCE INDICATES STATISTICAL GUIDANCE FAVORS THE FLAT INTENSIFICATION TREND, WHILE THE HWRF MODEL SUGGESTS INTENSIFICATION TO TROPICAL STORM STATUS IS A POSSIBILITY. MODEL TRACKS HOWEVER ARE IN GOOD AGREEMENT WITH THE FORECAST RECURVATURE SCENARIO. AS THIS IS THE INITIAL FORECAST WITH LIMITED AVAILABLE GUIDANCE, THE JTWC FORECAST CONFIDENCE IS ASSESSED AS LOW.// NNNN NNNN