WDPN31 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (KROSA) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.4N 145.3E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 716 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BANDING 
EYE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. 
ANIMATED WATER VAPOR IMAGERY INDICATES IMPROVING POLEWARD AND EASTWARD 
OUTFLOW AS THE UPPER-LEVEL TROUGH TO THE WEST CONTINUES TO FILL. 
HOWEVER, THERE IS SOME PRESSURE OVER THE SOUTHWESTERN QUADRANT, WITH 
NEGLIGIBLE IMPACT ON THE SYSTEM CURRENTLY. A 271604Z GMI 89GHZ COLOR 
COMPOSITE MICROWAVE IMAGE REVEALS TIGHTLY CURVED BANDING WRAPPING INTO 
A WELL-DEFINED SYMMETRIC MICROWAVE EYE FEATURE, WHICH SUPPORTS THE 
INITIAL POSITION WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 80 KTS 
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE T4.5-5.O (77 TO 90
KNOTS) DVORAK ESTIMATES AND THE CIMSS ADT, AIDT OBJECTIVE ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 79 KTS AT 271730Z
   CIMSS AIDT: 79 KTS AT 271730Z
   CIMSS D-MINT: 68 KTS AT 271828Z
   CIMSS D-PRINT: 76 KTS AT 271900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EASTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: PEAK INTENSITY HAS INCREASED FROM 70
KNOTS TO 90 KNOTS IN THE EARLY PORTION OF THE FORECAST PERIOD.

FORECAST DISCUSSION: TYPHOON (TY) 12W IS FORECAST TO TRACK NORTHWARD 
TO NORTH-NORTHWESTWARD THROUGH TAU 48 ALONG THE WESTERN PERIPHERY OF 
THE DEEP-LAYERED STR TOWARD A BREAK IN THE STR. TY 12W WILL INTENSIFY 
OVER THE NEXT 24 HOURS TO A PEAK OF 90 KNOTS AS THE SYSTEM CONTINUES 
TO CONSOLIDATE. AFTER TAU 24, THE STR IS FORECAST TO BUILD TO THE
NORTH, WHICH WILL RESULT IN A SIGNIFICANT DECREASE IN TRACK SPEEDS.
SLIGHT WEAKENING IS EXPECTED AFTER TAU 24 DUE TO DRY AIR ENTRAINMENT 
AND EVENTUALLY UPWELLING COOL WATER, WHICH WILL WEAKEN THE SYSTEM AS 
IT SLOWS FROM TAU 36 TO TAU 72. AFTER TAU 72, A MIDLATITUDE SHORTWAVE 
TROUGH WILL DEEPEN TO THE NORTH ALLOWING TY 12W TO RESUME A POLEWARD 
TRACK THROUGH TAU 120.   

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC GUIDANCE IS IN
FAIR AGREEMENT THROUGH TAU 24 THEN POOR AGREEMENT THEREAFTER. RELIABLE 
INTENSITY GUIDANCE IS IN POOR AGREEMENT THROUGH TAU 120.   

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW
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