Tropical Storm NEOGURI Advisory 10月22日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (NEOGURI) WARNING
NR 022//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 21W (NEOGURI), LOCATED APPROXIMATELY 247
NM SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED EAST-NORTHEASTWARD
AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS AN EXPOSED, ELONGATED LOW-LEVEL
CIRCULATION WITH DEEP CONVECTION SHEARED 180NM TO THE NORTHEAST.
THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION BASED ON THE
EXPOSED LLC IN EIR IMAGERY. THE SYSTEM IS EMBEDDED WITHIN A
MIDLATITUDE SHORTWAVE TROUGH AND ITS STRUCTURE HAS CONTINUED TO
DEFORM UNDER A HOSTILE ENVIRONMENT CHARACTERIZED BY STRONG (55
KNOTS) VERTICAL WIND SHEAR. HOWEVER, A 211241Z METOP-B ASCAT PASS
SHOWED A LARGE SWATH OF 45-50 KT WINDS TO THE NORTH OF THE SYSTEM,
WHICH MAINTAINS A BROAD, GALE-FORCE WIND FIELD. THE CURRENTINTENSITY
IS ASSESSED AT 45 KNOTS BASED ON THE AFOREMENTIONED ASCAT PASS, A
211649Z SATCON OF 47 KTS, AND THE PGTW EXTRATROPICAL METHOD FIX OF
T3.0 (45 KTS). THE SYSTEM IS ASSESSED AS EXTRATROPICAL BASED ON A
211100Z AMSU EDGE OF SWATH CORE TEMPERATURE CROSS SECTION SHOWING A
LOW LEVEL WARM FRONTAL ANOMALY AND A COLD CORE ALOFT, AS WELL AS THE
ASYMMETRIC WIND FIELD, DRY AIR FLOWING INTO THE DRY SLOT IN THE
CIMSS PRECIPITABLE WATER PRODUCT, SEA SURFACE TEMPERATURES BEING
UNFAVORABLY COLD AT 24-26 DEGREES CELSIUS, AND CONVECTION SHEARED
POLEWARD OF THE LOW-LEVEL CIRCULATION, ALL CHARACTERISTIC OF
EXTRATROPICAL SYSTEMS. TS 21W IS TRACKING NORTHEASTWARD ALONG THE
NORTHERN FLANK OF THE SUBTROPICAL RIDGE WITHIN THE STRONG
MIDLATITUDE WESTERLY FLOW.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE. WIND RADII WERE ADJUSTED
USING A 211241Z METOP-B ASCAT PASS.
   B. TS 21W IS FORECAST TO CONTINUE TRACKING NORTHEASTWARD THROUGH
THE FORECAST PERIOD AS AN EXTRATROPICAL SYSTEM. THE SYSTEM WILL
TRACK SOUTH OF TOKYO AND THEN EAST OF HONSHU MAINTAINING GALE-FORCE
WINDS. MODELS ARE HAVING DIFFICULTY RESOLVING THE EXACT POSITION IN
THE NEAR TERM, AS THE SYSTEM DEFORMS UNDER THE MID-LATITUDE WESTERLY
JET. THE JTWC FORECAST TRACK IS PLACED AHEAD OF THE MULTIMODEL
CONSENSUS, CLOSE TO THE UKMET AND GALWEM SOLUTIONS, AS CONSENSUS IS
BEING DRAGGED SLOWER BY GFS, WHICH PREDICTS A SIGNIFICANTLY SLOWER
AND MORE SOUTHERN TRACK. THERE IS LOW CONFIDENCE IN THE JTWC
FORECAST
TRACK.//
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