Tropical Storm FRANCISCO Advisory Sun Aug 04

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (FRANCISCO) WARNING
NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (FRANCISCO), LOCATED APPROXIMATELY 288 NM
EAST-SOUTHEAST OF CHICHI JIMA, HAS TRACKED NORTHWESTWARD AT 17 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 BASED ON A 030535Z SSMIS MICROWAVE IMAGE SHOWING BANDING
WRAPPING INTO THE LLCC. THE INTENSITY IS HEDGED BETWEEN THE
MULTI-AGENCY DVORAK INTENSITY ESTIMATES OF T2.5 (35 KTS) AND A
022122Z SATCON ESTIMATE OF 44 KNOTS. THE ENVIRONMENT, WITH GOOD
POLEWARD OUTFLOW AND LOW (10-15 KT) VERTICAL WIND SHEAR OFFSETTING
CONVERGENCE ALOFT FROM A TUTT CELL JUST TO THE WEST OF TS 09W, 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 60 KTS, WIND SPEEDS OF 65-
70 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 STAYS FAR
LEFT OF CONSENSUS THROUGH TAU 72, MODEL GUIDANCE IS IN GOOD AGREEMENT
FOR THIS PORTION OF THE FORECAST AND THE SPREAD IS LOW AT AROUND 150
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,
DESPITE POOR UPPER LEVEL DIVERGENCE, TS 09W SHOULD INTENSIFY AT A
SLIGHTLY FASTER RATE, REACHING 65-70 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 WEST OF
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 OVER COOLER (23-25 DEGREE
CELSIUS) SEAS. BASED ON GENERALLY GOOD AGREEMENT IN THE MODEL
GUIDANCE, THERE IS FAIR CONFIDENCE IN THE JTWC TRACK FORECAST.//
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