MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (IN-FA) WARNING NR 04// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 27W (IN-FA), LOCATED APPROXIMATELY 90 NM SOUTH OF POHNPEI, HAS TRACKED WEST-NORTHWESTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (IR) SATELLITE IMAGERY SHOWS DEEP CONVECTION WRAPPING AND BUILDING OVER THE LOW LEVEL CIRCULATION CENTER. A 171405Z GCOM-W1 36H MICROWAVE PASS IS STARTING TO INDICATE THE DEVELOPMENT OF AN EYE FEATURE. THE IR LOOP DOES NOT CURRENTLY INDICATE THE PRESENCE OF AN EYE FEATURE. DVORAK ESTIMATES FROM PGTW AND RJTD INDICATE A MARGINAL INCREASE IN INTENSITY OVER THE PAST SIX HOURS. THE CURRENT INTENSITY OF 45 KNOTS IS BASED ON THE IMPROVING DVORAK ESTIMATES AND THE PREVIOUSLY MENTIONED GCOM IMAGE. UPPER LEVEL ANALYSIS INDICATES RADIAL OUTFLOW WITH VERY LOW VERTICAL WIND SHEAR. THE SYSTEM CONTINUES TO TRACK UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE (STR) EXTENSION TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE PREVIOUS FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 27W WILL CONTINUE TO TRACK TO THE WEST-NORTHWEST THROUGHOUT THE FORECAST PERIOD BEING STEERED BY THE STR EXTENSION AND IN THE LATER TAUS BY THE MORE DOMINANT LOBE OF THE STR ANCHORED TO THE WEST OF GUAM. THE RIDGE WILL MAINTAIN ITS INTEGRITY, BEING MODIFIED ONLY SLIGHTLY BY THE FAIRLY ZONAL MID-LATITUDE WESTERLIES. INTENSIFICATION IS EXPECTED THROUGH TAU 72, SURPASSING TYPHOON STRENGTH AS THE ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE. IT SHOULD BE NOTED THAT DUE TO THE CURRENT HIGHLY FAVORABLE ENVIRONMENTAL CONDITIONS, TS IN-FA MAY INCREASE ITS INTENSITY AT A MORE RAPID RATE; HOWEVER, MODELS DO NOT CURRENTLY REFLECT THAT SCENARIO. C. BEYOND TAU 72, EXPECT A GREATER RATE OF INTENSIFICATION AS THE STR DEEPENS TO THE NORTHEAST OF THE SYSTEM. THIS WILL ALLOW FOR MORE POSITIVE OUTFLOW AND THE SYSTEM TO REACH 110 KNOTS BY THE END OF THE FORECAST PERIOD. MODEL GUIDANCE CONTINUES TO IMPROVE AND HAS COME INTO TIGHT AGREEMENT THROUGH TAU 72, WITH ONLY MINOR VARIATION THROUGH TAU 120. BASED ON THE IMPROVING MODEL GUIDANCE, THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK.// NNNN NNNN