WDPN32 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (MUIFA) WARNING NR 030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.3N 123.6E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 174 NM NORTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
APPROXIMATELY 35NM RAGGED EYE, WITH WELL DEFINED SPIRAL CONVECTIVE
BANDS WRAPPING TIGHTLY INTO THE CIRCULATION CENTER. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE
EVIDENT IN MULTISPECTRAL IMAGERY AND RADAR IMAGERY ALONG WITH
AGENCY DVORAK FIX DATA. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE, CONSERVATIVELY SET AT THE LOWER END OF
SUBJECTIVE DVORAK AND AUTOMATED INTENSITY ESTIMATES RANGING FROM 84
TO 94 KNOTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   CIMSS SATCON: 84 KTS AT 131740Z
   CIMSS ADT: 94 KTS AT 131430Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 14W IS EXPECTED TO CONTINUE GENERALLY
NORTH-NORTHWESTWARD FOR THE DURATION OF THE FORECAST PERIOD UNDER
THE PRONOUNCED STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST. OVER THE NEXT 12 HOURS, THE SYSTEM IS
EXPECTED TO MAINTAIN INTENSITY OR PERHAPS WEAKEN SLIGHTLY UNDER THE
MARGINAL ENVIRONMENTAL FACTORS SUCH AS STRONG POLEWARD OUTFLOW AND
LOW VERTICAL WIND SHEAR, WITH DECREASING SEA SURFACE TEMPERATURES
(SST) AS A POTENTIAL LIMITING FACTOR. AS 14W PROGRESSES ALONG ITS
TRACK, INCREASING VERTICAL WIND SHEAR BASED ON LATEST DECAY SHIPS
GUIDANCE SHOWS A STEADY INCREASE 15-20 KNOTS AND DECREASING SEA
SURFACE TEMPERATURES (SST) WILL CONTINUE TO INDUCE WEAKENING PRIOR
TO LANDFALL. HOWEVER, THE SYSTEM IS STILL EXPECTED TO MAKE LANDFALL
JUST SOUTH OF SHANGHAI AT OR NEAR MINIMAL TYPHOON INTENSITY AROUND
TAU 24. AFTER, STEADY WEAKENING WILL OCCUR AS THE SYSTEM MOVES
INLAND ALONG THE COASTLINE OF SOUTHEASTERN CHINA, WITH DISSIPATION
ANTICIPATED BY TAU 72.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD
AGREEMENT THROUGH TAU 48, WITH THE EXCEPTION OF NAVGEM AND
COAMPS-TC (COTI), THE ONLY NOTEWORTHY OUTLIERS ON THE WESTERN SIDE
OF THE GUIDANCE ENVELOPE. AFTER TAU 72 MODEL TRACK FORECAST
GUIDANCE DIVERGES GREATLY, GIVEN THE SYSTEM IS WELL INLAND BEING
IMPACTED BY HIGH VERTICAL WIND SHEAR AND LAND INTERACTION, LIKELY
RESULTING IN A MEANDERING MOTION OF THE REMNANT CIRCULATION.
ADDITIONALLY, BOTH GFS AND ECMWF ENSEMBLE MEMBERS ARE IN GOOD
AGREEMENT THROUGH THE NEAR TERM, WITH INCREASING SPREAD IN THE
EXTENDED TERM. THEREFORE, THE JTWC FORECAST IS PLACED WITH HIGH
CONFIDENCE THROUGH TAU 48, WITH MEDIUM CONFIDENCE BY TAU 72.
NUMERICAL MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT
THE FORECAST PERIOD. FOR THIS REASON THE JTWC INTENSITY IS PLACED
WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH//
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