Advisories

WDPN33 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (CHAN-HOM) WARNING NR 
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 36.0N 140.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 27 NM NORTHWEST OF NARITA AIRPORT
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 17 KTS

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 14W (CHAN-HOM) FULLY EXPOSED AND SCRAPING ACROSS CENTRAL
HONSHU. THE PLUME OF CENTRAL DEEP CONVECTION DISSIPATED IMMEDIATELY
FOLLOWING LANDFALL, LEAVING 14W COMPLETELY BARREN. SURFACE
OBSERVATIONS FROM THE REGION SUPPORT AN INTENSITY BETWEEN 30-35
KTS, WITH THE STRONGEST WINDS CONFINED TO THE NORTHERN SEMICIRCLE.
THE ENVIRONMENT REMAINS HIGHLY UNFAVORABLE, DOMINATED BY MOUNTAINOUS
TERRAIN, 30-35 KT VERTICAL WIND SHEAR, SUBSTANTIAL AMOUNTS OF
MID-LEVEL DRY AIR ENTRAINMENT, AND POOR DIVERGENCE ALOFT. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE FULLY
EXPOSED LLCC IN ANIMATED EIR. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE HOURLY SURFACE
OBSERVATIONS PROVIDED BY JAPAN.

INITIAL WIND RADII BASIS: ADJUSTED WIND RADII BASED OFF OF SURFACE
OBSERVATIONS IN HONSHU

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH
AND A DEEP UPPER LOW TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   CIMSS D-PRINT: 35 KTS AT 111130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30-35 KTS
   SST: OVER LAND
   OUTFLOW: WEAK EQUATORWARD
   OTHER FACTORS: SIGNIFICANT MID-LEVEL DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS 14W IS FORECAST TO CONTINUE SHREDDING ITSELF
OVER HONSHU WHILE IT REMAINS STEERED BY THE STR TO THE NORTH AND
DEEP-LAYER LOW TO THE SOUTH, WHICH ARE INDUCING A TIGHT STEERING
GRADIENT AND DRIVING 14W DUE WEST. 14W IS FORECAST TO REEMERGE OVER
WATER IN THE SEA OF JAPAN JUST AFTER TAU 12. HOWEVER, THE
ENVIRONMENT OVER WATER WILL BE NO MORE FAVORABLE THAN THE CURRENT
ONE, WITH UPWARDS OF 40 KTS OF VERTICAL WIND SHEAR AND
ADDITIONAL DRY AIR ENTRAINMENT. GIVEN THOSE FACTORS, 14W IS NOT
EXPECTED TO REINTENSIFY AFTER TAU 12, AND MAY NOT SURVIVE THE
JOURNEY TO THE SEA AT ALL. DISSIPATION IS FORECAST TO OCCUR NO
LATER THAN TAU 24.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGHOUT THE FORECAST PERIOD, SUPPORTING THE JTWC TRACK
FORECAST WITH HIGH CONFIDENCE. LIKEWISE, THE RELIABLE INTENSITY
AIDS ARE IN STRONG AGREEMENT IN STEADY WEAKENING THROUGH
DISSIPATION AT TAU 24. AS A RESULT, THE JTWC INTENSITY FORECAST IS
PLACED IN LINE WITH THE HAFS-A SOLUTION AND IS ASSESSED WITH HIGH
CONFIDENCE.


FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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