WDPN31 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 01W (EWINIAR) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.9N 126.7E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 401 NM SOUTH OF KADENA AB, OKINAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) HAS MOSTLY
MAINTAINED ITS CONVECTIVE SYMMETRICAL STRUCTURE WITH SLIGHT
DEGRADATION ALONG THE NORTHWEST QUADRANT AS IT ACCELERATED
NORTHEASTWARD. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON A MICROWAVE EYE IN THE 280517Z AMSR2 36GHZ PASS. THE
INITIAL INTENSITY IS PLACED WITH MEDIUM CONFIDENCE BASED ON OVERALL
ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK ESTIMATES AND REFLECTS
THE SLIGHT 6-HR DEGRADATION. ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT WITH WARM SST, LOW VWS, AND MODERATE OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS SATCON: 54 KTS AT 280540Z
   CIMSS ADT: 49 KTS AT 280520Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON EWINIAR WILL CONTINUE ITS ACCELERATED
TRACK NORTHEASTWARD ON THE POLEWARD SIDE OF THE STEERING STR. THE
ENVIRONMENT WILL GRADUALLY BECOME UNFAVORABLE AS VWS INCREASES AND
ALONG-TRACK SSTS DECREASE. SHORTLY AFTER TAU 48, THE SYSTEM WILL
BEGIN TO INTERACT WITH A BAIYU FRONTAL BOUNDARY AND BEGIN EXTRA-
TROPICAL TRANSITION (ETT) AND COMPLETE ETT BY BY TAU 96. THESE 
COMBINED DYNAMICS WILL GRADUALLY ERODE THE SYSTEM AND REDUCE TY 01W 
TO A MODERATE GALE-FORCE COLD-CORE LOW.   

MODEL DISCUSSION: NUMERICAL MODELS ARE IN EXTREMELY TIGHT AGREEMENT
LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST. HOWEVER, GIVEN
THE UNCERTAINTIES ASSOCIATED WITH ETT, THERE IS ONLY MEDIUM
CONFIDENCE IN THE INTENSITY FORECAST. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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