WDPN31 PGTW 281500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 01W (EWINIAR) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.4N 128.0E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 306 NM SOUTH OF KADENA AB, OKINAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 19 KTS
   SIGNIFICANT WAVE HEIGHT: 31 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS CONTINUED
DETERIORATION ALONG THE NORTHERN HEMISPHERE DUE TO SUBSIDENCE CAUSED 
BY A MIDLATITUDE TROUGH DIRECTLY ALOFT, AS EVIDENCED BY EROSION AND 
WARMING CLOUD TOPS OVER THE CENTRAL CONVECTION THAT IS OFFSET 
NORTHEASTWARD FROM THE LOW LEVEL CIRCULATION CENTER. THE INITIAL 
POSITION, EXTRAPOLATED FROM A MICROWAVE EYE IN THE 280911Z SSMIS 
36GHZ IMAGE, IS PLACED WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS 
PLACED WITH MEDIUM CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY 
AND OBJECTIVE DVORAK ESTIMATES THAT INDICATE A WEAKENING TREND, AND 
REFLECTS THE 6-HR DETERIORATION. ANALYSIS REVEALS A MARGINAL 
ENVIRONMENT WITH WARM SST, LOW VWS, AND MODERATE OUTFLOW OFFSET BY 
SUBSIDENCE ASSOCIATED WITH THE MIDLATITUDE TROUGH.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: SOUTHWESTWARD EXTENSION OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 47 KTS AT 281200Z
   CIMSS ADT: 58 KTS AT 281230Z
   CIMSS DMINT: 65 KTS AT 280911Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: A MIDLATITUDE TROUGH DIRECTLY ALOFT IS CAUSING
SUBSIDENCE ALONG THE NORTHERN HEMISPHERE OF THE SYSTEM.

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. BY TAU 48, THE SYSTEM WILL INTERACT WITH
A BAIYU FRONTAL BOUNDARY AND BEGIN EXTRA-TROPICAL TRANSITION (ETT)
AND COMPLETE ETT BY BY TAU 72. THESE COMBINED DYNAMICS WILL GRADUALLY 
ERODE THE SYSTEM AND REDUCE TY 01W TO A MODERATE GALE-FORCE COLD-CORE 
LOW BY END OF FORECAST.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY 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
   INTENSITY 0 - 72 HR: MEDIUM//
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