MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (FRANCISCO) WARNING NR 11// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 09W (FRANCISCO), LOCATED APPROXIMATELY 602 NM EAST-SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY REVEALS THE LOW LEVEL CIRCULATION CENTER (LLCC) BECOMING LESS OBSCURED BY THE CENTRAL DENSE OVERCAST AS SOME RELATIVELY DRY AIR WRAPS IN FROM THE SOUTH. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION WHICH WAS EXTRAPOLATED FROM A 030441Z GMI 89 GHZ MICROWAVE IMAGE THAT SHOWED A DEEP CONVECTIVE BAND WRAPPING IN ALONG THE SOUTHERN EDGE OF THE LLCC AND MOSTLY SHALLOW BANDS TO THE NORTHEAST. THE INITIAL INTENSITY OF 45 KNOTS FALLS BETWEEN MULTI-AGENCY DVORAK FIXES FROM T2.5-T3.0 (35-45 KNOTS) AND A SATCON ESTIMATE OF 52 KNOTS. A 032359Z METOP-B ASCAT PASS CONFIRMS THIS INTENSITY ESTIMATE AND DISPLAYS AN ASYMMETRIC WIND FIELD WITH THE STRONGEST WINDS CONTAINED IN THE NORTHERN SEMICIRCLE. THE ENVIRONMENT IS MARGINALLY FAVORABLE WITH LOW (10-15 KNOTS) VERTICAL WIND SHEAR (VWS) AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE (SST) BEING OFFSET BY FAIR POLEWARD OUTFLOW AND DRY AIR ENTRAINMENT FROM AN AREA OF UPPER-LEVEL CONVERGENCE TO THE SOUTH. TS 09W IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE OVERALL FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. THROUGH TAU 48, TS 09W IS FORECAST TO TRACK GENERALLY NORTHWESTWARD TOWARD SASEBO UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR. MODEL GUIDANCE IS IN GOOD AGREEMENT FOR THIS PORTION OF THE FORECAST WITH THE SPREAD AT 48 HOURS AT APPROXIMATELY 55 NM. AFTER PASSING SASEBO AROUND TAU 48, TS 09W IS EXPECTED TO BEGIN A GRADUAL POLEWARD TURN AS IT ROUNDS THE STR AXIS. UNTIL LANDFALL IN JAPAN AROUND TAU 36, TS 09W IS EXPECTED TO SLOWLY INTENSIFY TO AROUND 55 KNOTS AS THE ENVIRONMENT REMAINS MARGINAL DUE TO POOR UPPER LEVEL DIVERGENCE AND THE EFFECTS OF DRY AIR ENTRAINMENT. AFTER MAKING LANDFALL, TS 09W SHOULD WEAKEN OVER KYUSHU DUE TO THE RUGGED TERRAIN. A SECOND LANDFALL SHOULD OCCUR NEAR BUSAN, KOREA AROUND TAU 54. BASED ON TIGHT GROUPING OF THE MODEL DATA AND THE STEADY INFLUENCE OF THE STR, THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST. C. AFTER TAU 72, TS 09W WILL CONTINUE RECURVING AS IT ROUNDS THE STR AXIS, ACROSS THE EASTERN SIDE OF SOUTH KOREA, AND PASS INTO THE SEA OF JAPAN. THROUGHOUT THIS PERIOD, LAND INTERACTION, INCREASING VWS, AND COOLER SST SHOULD WEAKEN THE SYSTEM. BY TAU 96, TS 09W WILL BEGIN INTERACTING WITH THE MID-LATITUDE BAROCLINIC ZONE AND START UNDERGOING EXTRATROPICAL TRANSITION (ETT). ETT SHOULD COMPLETE PRIOR TO TAU 120. AS THE SYSTEM ROUNDS THE STR AXIS, SPREAD IN MODEL GUIDANCE INCREASES SIGNIFICANTLY, PRIMARILY DUE TO DIFFERENCES IN ALONG-TRACK SPEED. FOR THIS REASON, THERE IS LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.// NNNN NNNN