WDPN33 PGTW 270300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (NEOGURI) WARNING NR 035// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 31.5N 155.5E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 445 NM NORTH OF MINAMI TORI SHIMA MOVEMENT PAST 6 HOURS: EASTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM NEOGURI IS ENTERING THE BARE BEGINNINGS OF ITS NEXT PHASE OF INTERACTION WITH THE MID-LATITUDES AND THE EXTRA-TROPICAL TRANSITION (ETT) PROCESS. A VIGOROUS APPROACHING SHORT WAVE IS EVIDENT IN THE WATER VAPOR ANIMATION BUT THE ANIMATED VISUAL IMAGERY SHOWS THE CORE OF THE SYSTEM REMAINING ENSCONCED IN THE TROPICAL AIR MASS. THE WATER VAPOR SHOWS THE SYSTEM TAPPING INTO A POLEWARD OUTFLOW CHANNEL WHILE THE LOWER LEVELS HAVE INCREASED SYMMETRY OVER THE PAST SIX HOURS, WITH OVER-SHOOTING TOPS SHOWING OVER THE CORE. THERE ARE MINIMAL SIGNS OF STRETCHING OF THE CORE OR FRONTOGENESIS. THE SYSTEM HAS SHOWN THREE CONSECUTIVE FIXES OF EASTWARD MOVEMENT AND IS GRADUALLY ACCELERATING TOWARDS THE BAROCLINIC ZONE, WHICH REMAINS NORTH OF THE 40TH LATITUDE. THE INTENSITY ASSESSMENT IS RAISED A NOTCH ABOVE THE JTWC DVORAK DUE TO THE RELATIVELY SMALL SIZE OF THE SYSTEM, WHICH HAS BEEN RESULTING IN LOWER SUBJECTIVE AND OBJECTIVE ASSESSMENTS THROUGH THE STORMS LIFE-CYCLE. INITIAL WIND RADII BASIS: SCATTEROMETER DATA FROM A 262253Z ASCAT-B AND A 262341Z ASCAT-C THAT SANDWICHED BOTH PERIMETERS OF THE STORM BUT MISSED THE MIDDLE WERE STILL HELPFUL IN SETTING THE 35KT WIND RADII. CURRENT STEERING MECHANISM: THE WESTERN FLANK OF A SPLIT SUBTROPICAL RIDGE, WHICH IS ANCHORED IN 5990M H500 QS OVER THE DATELINE AND 34N AND BEGINNING TO INTERACT WITH A VIGOROUS MID-LATITUDE TROF APPROACHING FROM THE WEST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS RJTD: T3.5 - 55 KTS RCTP: T3.5 - 55 KTS KNES: T3.5 - 55 KTS CIMSS SATCON: 51 KTS AT 1730Z CIMSS ADT: 39 KTS AT 262030Z CIMSS AIDT: 57 KTS AT 262030Z CIMSS D-MINT: 49 KTS AT 262153Z CIMSS D-PRINT: 49 KTS AT 270000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 0-5 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL STORM NEOGURI WILL CONTINUE TRACKING POLEWARD AND GRADUALLY ACCELERATE TOWARDS THE BAROCLINIC ZONE. THE APPROACHING SHORT WAVE WILL SUCK DRY AIR INTO THE NORTHWEST QUADRANT AND BEGIN ERODING AND STRETCHING THE VORTEX. AS THE PATTERN CONTINUES TO AMPLIFY, TROPICAL STORM 25W WILL ACCELERATE AND WILL ENTER SIGNIFICANTLY COOLER WATERS NEAR TAU 24. THE EXTRA- TROPICAL TRANSITION PROCESS WILL THEN COMMENCE, BUT THE PROCESS WILL NOT COMPLETE UNTIL THE SYSTEM CROSSES THE 40TH LATITUDE. AS THE STORM MOVES INTO THE BAROCLINIC ZONE IT WILL ACTUALLY INTENSIFY DUE TO AN ENERGETIC POLAR FRONT JET AND TIGHT THERMAL PACKING AT THE GRADIENT LEVEL. THE SYSTEM IS EXPECTED TO TRANSITION INTO A HURRICANE FORCE MID-LATITUDE LOW AS IT COMPLETES THE ETT PROCESS. MODEL DISCUSSION: TRACKERS ARE TIGHT AND THERE IS VERY LITTLE ALONG-TRACK SPREAD DESPITE THE ACCELERATION. INTENSITY GUIDANCE IS ALSO UNANIMOUS IN SHOWING A STEEP INTENSIFICATION THROUGH THE FIRST 36 HOURS, WITH SOME AIDS INCLUDING HAFS-A REACHING 90KTS NEAR TAU 36. THE JTWC INTENSITY FORECAST FOLLOWS THE SAME TREND BUT LIMITS THE PEAK TO LOW TYPHOON STRENGTH. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: LOW// NNNN