WDPN31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (KROSA) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.8N 145.2E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 637 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAGGED
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 272025Z RCM-3 SAR IMAGE REVEALS A WELL-DEFINED CENTER,
WITH MAXIMUM WINDS OF 80-82 KNOTS OVER THE EASTERN QUADRANT, WHICH
SUPPORTS THE INITIAL INTENSITY ASSESSMENT OF 80 KTS WITH HIGH
CONFIDENCE.

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
   CIMSS ADT: 74 KTS AT 280000Z
   CIMSS AIDT: 70 KTS AT 280000Z
   CIMSS D-MINT: 68 KTS AT 271828Z
   CIMSS D-PRINT: 54 KTS AT 280030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG EASTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 (TY) 12W IS FORECAST TO TRACK
NORTH-NORTHWESTWARD TO NORTHWESTWARD THROUGH TAU 24 ALONG THE
WESTERN PERIPHERY OF THE DEEP-LAYERED STR TOWARD A BREAK IN THE
STR. TY 12W WILL MAINTAIN AN INTENSITY NEAR 75-80 KNOTS OVER THE
NEXT 24 HOURS. 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 12 DUE TO DRY AIR
ENTRAINMENT AND EVENTUALLY UPWELLING COOL WATER, WHICH WILL WEAKEN
THE SYSTEM AS IT SLOWS FROM TAU 24 TO TAU 48. AFTER TAU 48, 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: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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