Tropical Storm FRANCISCO Advisory 05.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (FRANCISCO) WARNING
NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (FRANCISCO), LOCATED APPROXIMATELY 369 NM
EAST-SOUTHEAST OF SASEBO, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT
17 KNOTS (KTS) OVER THE PAST SIX HOURS. THERE IS HIGH CONFIDENCE IN
THE INITIAL POSITION BASED ON ANIMATED MULTISPECTRAL SATELLITE
IMAGERY THAT REVEALS A TIGHTLY WRAPPED SYSTEM WITH A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) OCCASIONALLY OBSCURED BY
FLARING CONVECTION. THE INITIAL INTENSITY OF 55 KTS IS CONSISTENT
WITH THE PGTW DVORAK ESTIMATE OF T3.5 (55 KTS). THE ENVIRONMENT IS
MARGINALLY FAVORABLE WITH LOW (5-10 KT) VERTICAL WIND SHEAR (VWS),
WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE (SST), AND FAIR RADIAL
OUTFLOW BEING OFFSET BY DRY AIR ENTRAINMENT FROM AN AREA OF UPPER-
LEVEL CONVERGENCE TO THE SOUTHWEST. 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. IN THE NEAR TERM, TS 09W WILL CONTINUE ON A SIMILAR TRACK
ALONG THE SOUTHWEST PERIPHERY OF THE STR, MAKE LANDFALL OVER KYUSHU
AROUND TAU 18, AND PASS NEAR SASEBO JUST AFTER TAU 24. SECOND
LANDFALL WILL OCCUR NEAR BUSAN, KOREA AROUND TAU 36 AS THE CYCLONE
STARTS ROUNDING THE STR AXIS. SHORTLY AFTER TAU 48, TS 09W WILL HAVE
ROUNDED THE STR AXIS, BEGIN TRACKING NORTHEASTWARD OVER THE SEA OF
JAPAN, AND START EXTRATROPICAL TRANSITION (ETT) AS IT INTERACTS WITH
THE MID-LATITUDE BAROCLINIC ZONE. THE MARGINAL ENVIRONMENT SHOULD
INHIBIT FURTHER INTENSIFICATION BEFORE LANDFALL. AFTER LANDFALL, THE
SYSTEM WILL WEAKEN DUE TO LAND INTERACTION AS IT RAPIDLY TRACKS OVER
JAPAN AND KOREA. BY THE TIME TS 09W EMERGES INTO THE SEA OF JAPAN,
INTENSITY IS EXPECTED TO BE AROUND 35 KTS. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT THROUGH TAU 72, LENDING TO HIGH CONFIDENCE IN THIS
PORTION OF THE JTWC TRACK FORECAST.
   C. AFTER TAU 72, TS 09W WILL TRACK EAST-NORTHEASTWARD AND
COMPLETE ETT AROUND TAU 96. DESPITE COOL SST AND HIGH VWS, THE
INTENSITY SHOULD INCREASE SLIGHTLY AS IT TRANSITIONS INTO A COLD-
CORE LOW. FOR THIS PORTION OF THE FORECAST, SPREAD IN THE MODEL
GUIDANCE INCREASES SLIGHTLY DUE TO DIFFERENCES IN ALONG-TRACK SPEED,
LENDING TO FAIR CONFIDENCE IN THE EXTENDED TRACK FORECAST.//
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