MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS) WARNING NR 06// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 06W (DANAS), LOCATED APPROXIMATELY 421 NM SOUTH- SOUTHWEST OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THAT CONVECTION WRAPPING IN FROM THE EAST HAS OBSCURED THE LOW LEVEL CIRCULATION CENTER (LLCC). THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION WHICH IS BASED ON A 171051Z GMI 89 GHZ MICROWAVE IMAGE WHICH REVEALS THE CONVECTION IS ABOUT 25 NM TO THE EAST OF THE LLCC. A PARTIAL 171251Z METOP-A ASCAT PASS DEPICTS AN EXPANSIVE REGION OF 30 KT WINDS AND POCKETS OF 35 KT WINDS TO THE SOUTHEAST OF THE LLCC. THE CONVECTION TO THE WEST (INVEST 91W) NOW APPEARS LIKELY TO BREAK AWAY FROM 06W, POSSIBLY FORMING A DISTINCT TROPICAL CYCLONE IN THE NEXT 24 TO 48 HOURS. THE INITIAL INTENSITY OF 35 KTS IS SLIGHTLY ABOVE MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES THAT ARE T2.0 AND BELOW (30 KTS OR LESS) BASED ON THE AFOREMENTIONED ASCAT PASS. THE ENVIRONMENT IS FAVORABLE WITH WARM (30-31 CELSIUS) SEA SURFACE TEMPERATURE, MODERATE (10-20 KTS) VERTICAL WIND SHEAR (VWS), AND FAIR EQUATORWARD AND POLEWARD OUTFLOW CHANNELS. TS 06W IS TRACKING ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 06W WILL CONTINUE TRACKING POLEWARD THROUGH TAU 48 BEFORE BEGINNING A NORTHEASTWARD TURN AS IT ROUNDS THE STR AXIS. CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS SHOULD SUPPORT INTENSIFICATION AND TS 06W IS EXPECTED TO REACH ABOUT 50 KTS AROUND TAU 48. AFTER TAU 48, DIMINISHED OUTFLOW AND LAND INTERACTION SHOULD CAUSE GRADUAL WEAKENING. WITH THE EXCEPTION OF A WESTERN OUTLIER (NAVGEM), TRACK GUIDANCE HAS COME INTO BETTER AGREEMENT FOR THIS PORTION OF THE FORECAST. AT TAU 72, CROSS-TRACK SPREAD AMONG THE BULK OF THE MEMBERS IS AROUND 120 NM (OF NOTE, ALONG-TRACK UNCERTAINTY AMONG THE MEMBERS IS HIGHER). THE JTWC TRACK FORECAST CLOSELY FOLLOWS THE CONSENSUS TRACK WITH FAIR CONFIDENCE, OWING TO THE HIGH ALONG-TRACK SPREAD, THROUGH TAU 72. C. BEYOND TAU 72, TS 06W IS EXPECTED TO RECURVE NORTHEASTWARD AND BEGIN GRADUALLY UNDERGOING EXTRATROPICAL TRANSITION AS IT PASSES NEAR JAPAN. SLIGHT WEAKENING IS ANTICIPATED, ALTHOUGH BAROCLINIC INTERACTION WITH A MID-LATITUDE TROUGH SHOULD MAINTAIN 35 KNOTS OR GREATER THROUGHOUT THE TRANSITION. REGARDING THE TRACK, BOTH CROSS- TRACK AND ALONG-TRACK UNCERTAINTY INCREASES SIGNIFICANTLY FOR THIS PORTION OF THE FORECAST AND THE CONSENSUS TRACK BECOMES UNREPRESENTATIVE OF A TYPICAL RECURVING CYCLONE. BECAUSE THE CONSENSUS TRACK IS UNREALISTIC FOR THE LATER TAUS, THE JTWC TRACK FORECAST FOLLOWS A BLEND OF TRACKS FROM SEVERAL MEMBERS (ECMWF, GFS, AND THEIR ENSEMBLE MEANS) WITH LOW CONFIDENCE BEYOND TAU 72.// NNNN NNNN