WDPN31 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (HINNAMNOR) 
WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.8N 127.7E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 102 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
A WELL ORGANIZED SYSTEM WITH TIGHTLY WRAPPING CLOUD LINES FORMING
AROUND AN 8NM EYE. ANIMATED RADAR IMAGERY INDICATES THAT 12W IS
UNDERGOING AN EYE WALL REPLACEMENT CYCLE SHOWING A WELL DEFINED
INNER EYE WALL, A SIZEABLE MOAT AND SECONDARY EYE WALL ABOUT 25NM
OUT FROM THE CENTER. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON EIR AND ANIMATED RADAR IMAGERY. THE INITIAL
INTENSITY OF 125 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
PGTW DVORAK INTENSITY ESTIMATES SHOWING T6.0 AND CIMSS SATCON AND
ADT SHOWING 124 KTS AND 122 KTS RESPECTIVELY WHILE KNES REPORTS
T5.5. FURTHERMORE, BASED ON THE ONGOING ERC, WE WOULD EXPECT SOME
DEGREE OF WEAKENING AS THIS PROCESS DEVELOPS AND THE INNER EYE IS
CHOKED OFF AND REPLACED.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE WEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 124 KTS AT 310752Z
   CIMSS ADT: 122 KTS AT 311140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 WEST-SOUTHWESTWARD 
UNDER THE GROWING INFLUENCE OF A STR TO THE WEST. THROUGH TAU 36, 12W 
WILL EVENTUALLY BE TRACKING GENERALLY SOUTHWESTWARD IN A COMPETING 
STEERING ENVIRONMENT, ALL THE WHILE TD 13W WHICH IS ATTEMPTING TO 
DEVELOP TO ITS SOUTH WILL INCREASES ITS INTERACTION WITH 12W FURTHER 
EXACERBATING ITS EQUATORWARD TREND. AFTER TAU 24, 12W WILL FIND 
ITSELF IN A NEAR QUASI-STATIONARY ENVIRONMENT TRAPPED BETWEEN 
COMPETING RIDGES TO THE WEST AND EAST, AND A NEAR EQUATORIAL RIDGE 
(NER) BUILDING IN TO THE SOUTH, THIS COUPLED WITH ONGOING ERC AND 
INCREASING SHEAR WILL STEADILY WEAKEN THE SYSTEM. IN THIS ENVIRONMENT 
UP WELLING OF COOLER WATER WILL ALSO HAVE A MAJOR IMPACT ON THE 
SYSTEMS INTENSITY. NEAR TAU 36, A MID-LATITUDE SHORTWAVE TROUGH WILL 
BEGIN TO DEVELOP OVER NORTHWEST CHINA, AND BEGIN TO ERODE THE WESTERN 
RIDGE, MEANWHILE THE ENHANCED SOUTHWEST MONSOONAL FLOW WILL BUILD A 
STRONG RIDGE TO THE NORTHEAST OF THE SYSTEM. THESE TWO FACTORS 
COALESCE AND FORCE 12W TO MOVE GENERALLY NORTHWARD. BY TAU 72 AS 
TRACK SPEEDS INCREASE THERE IS A NOTABLE POTENTIAL FOR THE SYSTEM TO 
REINTENSIFY THROUGH THE FORECAST PERIOD THOUGH IT IS UNLIKELY TO 
REACH ITS FORMER PEAK INTENSITY.


MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE CONTINUES TO TIGHTEN
AROUND THE JTWC FORECAST TRACK, WITH THE EXCEPTION OF NAVGEM AND
COAMPS-TC (NAVGEM VERSION) WHICH MAKE AN UNREALISTIC TURN INTO THE
NER TO THE SOUTH BEFORE TURNING POLEWARD. THIS INCREASING
CONSOLIDATION OF MEMBERS HAS LED TO A HIGH CONFIDENCE IN THE NEAR
TERM AND A MEDIUM TRACK CONFIDENCE IN THE EXTENDED FORECAST.
SIMILAR TO TRACK GUIDANCE, RELIABLE MODEL INTENSITY GUIDANCE HAS
ALSO TIGHTENED, THERE IS NOW ONLY A 20 KNOT ENVELOPE THROUGH TAU
48, AND THIS CONSENSUS WOULD EXTEND NEARLY THROUGH THE FORECAST
PERIOD BUT COAMPS-TC AND HWRF TAKE A SHARP NOSE DIVE AFTER TAU 36
BEFORE REJOINING THE PACK NEAR TAU 96. THERE REMAINS SIGNIFICANT
DISCREPANCY AFTER TAU 96 AS THE GUIDANCE IS SPLIT BETWEEN GRADUAL
WEAKENING AND CONTINUED INTENSIFICATION. FOR THESE REASONS THE JTWC
INTENSITY FORECAST IS PLACED INITIALLY WITH MEDIUM CONFIDENCE AND
IN THE EXTENDED FORECAST WITH LOW CONFIDENCE.

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