Tropical Storm TALAS Advisory 9月24日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (TALAS)
WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 32.9N 137.2E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 190 NM SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
RAPIDLY-WEAKENING, RAGGED LOW-LEVEL CIRCULATION (LLC) EMBEDDED IN
THE FRONTAL BOUNDARY WITH DEEP CONVECTION SHEARED 140NM
NORTH-NORTHEAST. ANIMATED RADAR IMAGERY SHOWS A FRONTAL BAND
EXTENDING FROM HONSHU SOUTHWARD WITH NO DEFINED LLC DUE TO THE
SHALLOW, WEAK NATURE OF THE SYSTEM. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE EIR IMAGERY. THE INITIAL
INTENSITY OF 25 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
DVORAK DATA-T ESTIMATES AND CIMSS ADT ESTIMATE. TD 17W IS LOCATED
WITHIN AN UNFAVORABLE ENVIRONMENT UNDER THE UPPER-LEVEL WESTERLIES
WITH MODERATE TO STRONG VERTICAL WIND SHEAR, AND IS INTERACTING
WITH THE BAROCLINIC ZONE.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF THE LOW- TO
MID-LEVEL SUBTROPICAL RIDGE (STR)
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   CIMSS SATCON: 35 KTS AT 231714Z
   CIMSS ADT: 25 KTS AT 231750Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: BAROCLINIC INTERACTION AND DRY AIR ENTRAINMENT
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TD 17W WILL CONTINUE TRACKING EAST-NORTHEASTWARD
ALONG THE NORTHWESTERN PERIPHERY OF THE LOW-LEVEL STR THROUGH THE
FORECAST PERIOD. THE SYSTEM IS RAPIDLY WEAKENING AND IS FORECAST TO
DISSIPATE WITHIN THE NEXT 06-24 HOURS AS IT BECOMES ABSORBED IN THE
FRONTAL BOUNDARY. THE NEXT WARNING AT 240000Z WILL LIKELY BE THE
FINAL WARNING ON THIS SYSTEM.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT AND
GENERALLY SUPPORTS THE JTWC FORECAST TRACK SOUTH OF HONSHU WITH
MEDIUM CONFIDENCE. THE BULK OF THE INTENSITY GUIDANCE INDICATES
STEADY WEAKENING WITH THE EXCEPTION OF HWRF, WHICH SHOWS AN
INCREASE TO 33 KNOTS AT TAU 12 THEN STEADY WEAKENING. THIS
INTENSIFICATION IS ASSOCIATED WITH A SURGE OF STRONGER NORTHERLY
WINDS OVER THE NORTHWEST QUADRANT ASSOCIATED WITH THE BAROCLINIC
ZONE.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
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