Tropical Storm FRANCISCO Advisory Sat Aug 03

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (FRANCISCO) WARNING
NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 09W (FRANCISCO), LOCATED APPROXIMATELY 296 NM WEST
OF MINAMI TORI SHIMA, HAS TRACKED NORTHWESTWARD AT 18 KNOTS OVER THE
PAST SIX HOURS. THE LOW LEVEL CIRCULATION CENTER (LLCC) IS OBSCURED
BY CONVECTIVE CLOUD TOPS IN ANIMATED MULTISPECTRAL SATELLITE
IMAGERY. DESPITE THAT, THERE IS HIGH CONFIDENCE IN THE INITIAL
POSITION, WIND RADII, AND INTENSITY BASED ON A 030020Z METOP-B ASCAT
IMAGE. THE INTENSITY DEPICTED BY THE ASCAT IMAGE IS ON THE HIGH SIDE
OF MULTI-AGENCY DVORAK INTENSITY ESTIMATES OF T2.5 (35 KTS). THE
ENVIRONMENT, WITH GOOD EQUATORWARD OUTFLOW AND MODERATE (15-20 KT)
VERTICAL WIND SHEAR OFFSETTING CONVERGENCE ALOFT FROM A TUTT CELL
JUST WEST OF THE SYSTEM, IS MARGINAL FOR DEVELOPMENT. 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. NOTABLY, DESPITE THE MAX
WIND DEPICTED ON THE WARNING GRAPHIC BEING 65 KTS, WIND SPEEDS OF 75-
80 KTS ARE EXPECTED AROUND TAU 60, AS TS 09W MAKES LANDFALL ON
KYUSHU. THE TIMING OF THE STRONGER WINDS FALLS BETWEEN TAU 48 AND 72
AND IS NOT DISPLAYED ON THE WARNING GRAPHIC.
   B. THROUGH TAU 72, TS 09W IS FORECAST TO TRACK GENERALLY
NORTHWESTWARD TOWARD SASEBO UNDER THE STEERING INFLUENCE OF THE
AFOREMENTIONED STR. WITH THE EXCEPTION OF JGSM, WHICH IS A SOUTHERN
OUTLIER, MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT FOR THIS
PORTION OF THE FORECAST AND THE SPREAD IS WELL BELOW 200 NM AT TAU
72. TS 09W SHOULD INTENSIFY SLOWLY THROUGH ABOUT TAU 30 DUE TO THE
CONTINUED INFLUENCE OF THE FILLING TUTT CELL. AFTER TAU 30, TS 09W
SHOULD BE ABLE TO INTENSIFY AT A FASTER RATE, REACHING 75-80 KTS AS
IT MAKES LANDFALL OVER KYUSHU, JAPAN AROUND TAU 60. AFTER MAKING
LANDFALL, THE RUGGED TERRAIN SHOULD SIGNIFICANTLY WEAKEN THE
INTENSITY BY TAU 72.
   C. BEYOND TAU 72, TS 09W WILL GRADUALLY TURN POLEWARD AS IT
STARTS TO ROUND THE STR AXIS AND MAKE A SECOND LANDFALL NEAR BUSAN,
KOREA. ALTHOUGH NAVGEM AND GFS ARE EAST OF THE OTHER MEMBERS, MODEL
GUIDANCE IS IN FAIR AGREEMENT ABOUT THE TRACK. BY TAU 120, TS 09W
WILL BEGIN INTERACTING WITH THE MID-LATITUDE BAROCLINIC ZONE AND
START UNDERGOING EXTRATROPICAL TRANSITION. BASED ON GENERALLY GOOD
AGREEMENT IN THE MODEL GUIDANCE, THERE IS FAIR CONFIDENCE IN THE
JTWC TRACK FORECAST.//
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