WDPN31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (HINNAMNOR) 
WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.5N 124.7E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 206 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A WELL
DEFINED SYSTEM WITH SPIRAL BANDS OF CONVECTION AND DRY AIR IMPEDING
ITS WESTERN FLANK. A 030944Z SSMIS 89GHZ COLOR COMPOSITE MICROWAVE
IMAGE INDICATES A SMALL MICROWAVE EYE FEATURE WITH DEEP BANDS OF
CONVECTION HEAVILY FAVORING THE EASTERN SIDE. THE INITIAL POSITION
IS PLACED WITH MEDIUM CONFIDENCE BASED ON EIR AND SSMIS MICROWAVE
IMAGERY. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON AGENCY DVORAK INTENSITY ESTIMATES REMAINING
CONSERVATIVE AT (75-77KTS) WHILE CIMSS REMAINS HIGHER AT 87 KTS.
THIS REGION OF DVORAK INTENSITY AND METHOD SHIFT FROM WRAPPING TO
EYE METHOD IS NOTORIOUSLY TRICKY. IF AN EYE CONSOLIDATES AND CLEARS
THIS CAN CAUSE DVORAK INTENSITY ESTIMATES TO JUMP TO T5.0 - T5.5.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP SUBTROPICAL
RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 87 KTS AT 030840Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 12W IS CURRENTLY TRACKING GENERALLY
NORTHWARD UNDER THE STEERING INFLUENCE OF A STR TO THE EAST.
SURFACE OBSERVATION FROM ISHIGAKIJIMA AND MIYAKOJIMA INDICATE WINDS
FROM RECIPROCAL DIRECTIONS CONFIRMING THAT 12W IS DIRECTLY BETWEEN
THE TWO ISLANDS AND SET TO ENTER THE EAST CHINA SEA IN THE COMING
HOURS. THE SYSTEM IS STILL BATTLING SIGNIFICANT DRY AIR ON ITS
WESTERN FLANK DUE TO A DEEP LAYERED STR TO ITS WEST. THIS NORTHERLY
DRY AIR IS NOT ONLY INHIBITING CONVECTION BUT ALSO PREVENTING
SIGNIFICANT OUTFLOW TO THE WEST. HOWEVER AS THE SYSTEM PROGRESSES
NORTHWARD THROUGH TAU 24 THIS INTERACTION WILL DECREASE AND
INTENSITIES WILL BE ABLE TO RISE. BY TAU 36, THE SYSTEM WILL REACH
ITS PEAK NEAR 105KTS OR POSSIBLY HIGHER AS IT BRIEFLY TAPS INTO A
GOOD POLEWARD OUTFLOW CHANNEL WHICH IS THE HERALD OF ITS IMPEDING
EXTRATROPICAL TRANSITION. BY TAU 48, TY 12W WILL BE TRACKING
NORTHEASTWARD AS ITS STEERING RIDGE REORIENTS DUE TO A STRONG
MID-LATITUDE TROUGH APPROACHING FROM THE WEST, THIS INTERACTION
WILL ALSO GREATLY INCREASE TRACK SPEEDS. AS THIS TROUGH DIGS DOWN
OVER THE KOREAN PENINSULA, 12W WILL EXPERIENCE DRAMATICALLY HIGHER
SHEAR AND WILL BEGIN TO INTERACT WITH THE PENINSULA ITSELF FURTHER
WEAKENING THE SYSTEM. AS 12W CROSSES THE SOUTHERN COAST OF KOREA
NEAR TAU 60 IT INTERACTS WITH AND INCORPORATES INTO THE
MID-LATITUDE WESTERLY FLOW ALOFT AND WILL BEGIN EXTRA-TROPICAL
TRANSITION. THIS TRANSITION CONTINUES THROUGH TAU 72 AND BY TAU 96
THE SYSTEM WILL COMPLETE EXTRATROPICAL TRANSITION IN THE NORTHERN
SEA OF JAPAN.

MODEL DISCUSSION: WITH THE EXCEPTION OF COAMPS-TC (NAVGEM VERSION),
NUMERICAL MODELS ARE IN TIGHT AGREEMENT THROUGH TAU 48 WITH A 65NM
SPREAD IN SOLUTIONS, BY TAU 72 THIS SPREAD DOUBLES AND BY TAU 96
ALONG TRACK AND CROSS TRACK SOLUTIONS SPREAD AGAIN. FOR THESE
REASONS THE INITIAL JTWC TRACK FORECAST IS PLACED WITH HIGH
CONFIDENCE, AND THE EXTENDED TRACK IS PLACED WITH MEDIUM
CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT
WITH A FEW ACCEPTATIONS. BOTH VERSIONS OF DECAY-SHIPS (GFS AND
NVGM) INDICATE STAGNATION AND EVENTUAL WEAKENING UNTIL DISSIPATION
WHILE THE REMAINING GUIDANCE INDICATES SOME LEVEL OF
INTENSIFICATION THROUGH TAU 24 - TAU 36 WITH THE NOTABLE ADDITION
OF TWO RAPID INTENSIFICATION AIDS.  AFTER TAU 36, THE BULK OF THE
GUIDANCE TRENDS DOWNWARD THROUGH THE FORECAST PERIOD. DUE TO THE
SPREAD IN INTENSITY GUIDANCE THE JTWC FORECAST INTENSITY IS PLACED
WITH MEDIUM CONFIDENCE.

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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