Tropical Storm FRANCISCO Advisory 24.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FRANCISCO) WARNING NR 33//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 26W (FRANCISCO), LOCATED APPROXIMATELY 129 NM SOUTHEAST
OF KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT 02 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS AN ALMOST QUASI-STATIONARY SYSTEM WITH SLIGHTLY IMPROVED
CENTRAL CONVECTION OVER A LOW-LEVEL CIRCULATION CENTER (LLCC) THAT
HAS SLIGHTLY DEVOLVED OVER THE PAST 12 HOURS. OVERALL, DEEP
CONVECTION HAS SHALLOWED DUE TO THE CONTINUED EFFECTS OF MARGINAL
SEA SURFACE TEMPERATURES (NEAR 26 DEGREES CELSIUS) AND DRY AIR
ENTRAINMENT, HOWEVER, TY 26W HAS MAINTAINED ITS STRUCTURE RELATIVELY
WELL AS IT SLOWLY TRACKS AROUND THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR). A 232316Z SSMIS MICROWAVE IMAGE REVEALS THE
DEVOLVING STRUCTURE OF THE BROADENED LLCC AS THE CONVECTION HAS
SIGNIFICANTLY SHALLOWED. THE CURRENT POSITION IS BASED UPON THE MSI
LOOP, RADAR FIXES FROM RJTD, AND THE AFOREMENTIONED MICROWAVE IMAGE
WITH HIGH CONFIDENCE. THE CURRENT INTENSITY HAS BEEN MAINTAINED AT
65 KNOTS BASED ON THE HIGH END OF DVORAK INTENSITY ESTIMATES FROM
PGTW AND RJTD. UPPER LEVEL ANALYSIS INDICATES A STRONG POLEWARD
OUTFLOW CHANNEL CONTINUES TO BE ENHANCED BY THE MID-LATITUDE
WESTERLIES ALTHOUGH VERTICAL WIND SHEAR (VWS) HAS STARTED TO
INCREASE TO MODERATE (15-25 KNOTS) LEVELS.  TY 26W HAS SIGNIFICANTLY
SLOWED AS THE STR LOCATED TO THE NORTHEAST OF THE SYSTEM BEGINS TO
MODIFY IN RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH THAT IS
CURRENTLY LOCATED OVER THE KOREAN PENINSULA.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING.
   B. IN THE NEXT 12 HOURS, TY 26W IS EXPECTED TO SLOWLY TURN NORTH
AND ROUND THE MODIFYING STR. MEANWHILE, THE APPROACHING MID-LATITUDE
TROUGH WILL CONTINUE TO PROPAGATE EASTWARD TOWARDS JAPAN. AS TY 26W
GAINS LATITUDE, THE MODIFYING STR WILL ACCELERATE TY 26W TO THE
NORTHEAST. FURTHER DECREASING SSTS AND INCREASING VWS FROM THE
TROUGH WILL LEAD TO A SLOW WEAKENING TREND THROUGH TAU 72. AFTER TAU
72, TY 26W WILL CONTINUE TO ACCELERATE TO THE NORTHEAST UNDER THE
INFLUENCE OF THE MODIFYING STR AND PRESSING MID-LATITUDE TROUGH.
FURTHER WEAKENING IS EXPECTED AS THE SYSTEM TRACKS TO THE NORTHEAST
AND ENVIRONMENTAL PARAMETERS CONTINUE TO ERODE THE SYSTEM. EXTRA-
TROPICAL TRANSITION AND INTERACTION WITH THE BAROCLINIC ZONE WILL
BEGIN AROUND TAU 48, WITH COMPLETE TRANSITION TO A COLD-CORE SYSTEM
EXPECTED BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48, LENDING TO HIGH CONFIDENCE IN THE EARLY PORTION OF
THE FORECAST. AFTER TAU 48, THE MODELS BEGIN TO DIVERGE AS THERE ARE
SLIGHT VARIANCES IN THE EXTENT OF THE STR AS THE TROUGH MOVES INTO
THE AREA. DUE TO THIS, LOW CONFIDENCE REMAINS IN THE LATER TAUS
WHICH IS LAID CLOSE TO, BUT SLIGHTLY FASTER THAN, MULTI-MODEL
CONSENSUS.//
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