WDPN31 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.7N 126.7E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 412 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLIGHTLY
ASYMMETRIC TYPHOON STRENGTH CIRCULATION WITH A RAGED 5-10NM EYE.
EQUATORWARD OUTFLOW IS DRIVING INCREASED CONVECTION TO THE SOUTH OF
THE LLCC WHILE INCREASING MID-LEVEL VWS AND DRY AIR ENTRAINMENT ARE
PUTTING PRESSURE ON THE NORTHERN QUADRANT, RESULTING IN THIS
ASYMMETRIC APPEARANCE. THE SSMIS IMAGERY ALSO INDICATES AN EYE
WALL HAS FORMED AND THE BEGINNINGS OF A MOAT BEYOND THAT. THOUGH
CIMSS M-PERC VALUES HAVE CLIMBING TO ROUGHLY 30 PERCENT, IT IS
UNLIKELY THE SYSTEM WILL REMAIN IN THE REQUISITE INTENSITY BAND TO
PROGRESS THOUGH AN ERC. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY OF
105 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE MAJORITY OF
INTENSITY ESTIMATES INCLUDING AGENCY DVORAK AND CIMSS AUTOMATED
ESTIMATES INDICATING 105KTS WITH MINIMAL DEVIATION.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 104 KTS AT 020220Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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 14W (KOINU) IS FORECAST TO CONTINUE ON
A GENERALLY NORTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE
DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. AS
EVIDENCED BY THE ASYMMETRIC APPEARANCE IN MSI AND MICROWAVE
IMAGERY, 14W IS EXPERIENCING INCREASED MID-LEVEL VERTICAL WIND
SHEAR AND DRY AIR ENTRAINMENT. OVER THE NEXT 12 HOURS, THESE
NEGATIVE FACTORS ARE GENERALLY NEGATED BY FAVORABLE OUTFLOW ALOFT
WHICH IS FORECAST TO ALLOW FOR ADDITIONAL INTENSIFICATION. BY TAU
24 HOWEVER, AFTER REACHING A PEAK INTENSITY NEAR 110KTS, FAVORABLE
EQUATORWARD OUTFLOW IS LOST WHICH WHEN COUPLED WITH INCREASING
MID-LEVEL VWS AND DRY AIR ENTRAINMENT, THE SYSTEM WILL BEGIN TO
GRADUALLY WEAKEN. AS THE STR TO THE EAST BUILDS WESTWARD, 14W WILL
BE FORCED TOWARDS THE SOUTHERN TIP OF TAIWAN AS IT CONTINUES TO
SLOWLY WEAKEN. AFTER MAKING LANDFALL NEAR TAU 60, THE MOUNTAINOUS
EASTERN COAST OF TAIWAN WILL QUICKLY WEAKEN 14W TO 80KTS BY TAU 72.
IN THE EXTENDED TRACK, 14W IS FORECAST TO SLOWLY TRANSIT THE TAIWAN
STRAIT AS MORE COOL DRY AIR STEAMS INTO THE SYSTEM FROM THE NORTH,
RESULTING IN CONTINUED WEAKENING THROUGH TAU 120 AS THE SYSTEM
APPROACHES MAINLAND CHINA.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH ALL
MEMBERS CLOSELY FOLLOWING THE JTWC FORECAST TRACK THROUGH TAU 36.
BY TAU 72, MEMBER GUIDANCE REMAINS IN FAIR AGREEMENT WITH A 150NM
SPREAD IN SOLUTIONS. FOR THIS REASON THE JTWC FORECAST TRACK IS
PLACED INITIALLY WITH HIGH CONFIDENCE AND WITH MEDIUM CONFIDENCE
THEREAFTER. RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT
WITH MOST MEMBERS INDICATING LIMITED INTENSIFICATION THROUGH TAU
24, AFTER WHICH CONTINUOUS WEAKENING THROUGH THE FORECAST PERIOD.
THE ONE EXCEPTION TO THIS HAPPY STORY IS COAMPS-TC (GFS VERSION),
WHICH IS THE ONLY MEMBERS TO NOT MAKE LANDFALL OVER TAIWAN AND AS A
RESULT SHOWS CONTINUOUS INTENSIFICATION THROUGH TAU 120. DESPITE
THIS HOLDOUT, THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL
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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