WDPN33 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (KRATHON) WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
 
SUMMARY:
   INITIAL POSITION: 20.1N 122.0E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 301 NM SOUTH OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET
 
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATED 
AND WELL-ORGANIZED TYPHOON 20W (KRATHON) WITH A 20-NM DIAMETER EYE 
THAT HAS SHRUNK BY 2 NM AND WARMED FROM 12 TO 17 DEGREES CELSIUS, DUE 
TO COMPRESSIONAL WARMING OF THE SUBSIDING AIR, INDICATING STEADY 
INTENSIFICATION. THE MSI LOOP ALSO SHOWS CONTINUED STRONG RADIAL 
OUTFLOW WITH ASSOCIATED SPIRAL BANDS OF DEEP CONVECTION BECOMING MORE 
COMPACT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
BASED ON THE WELL-DEFINED EYE IN THE MSI LOOP THAT LINED UP WELL WITH  
A MICROWAVE EYE IN THE 292138Z F17 SSMIS IMAGE SUITE. THE INITIAL 
INTENSITY OF 115 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON 
CLOSELY-VALUED AGENCY AND AUTOMATED DVORAK FIXES, AS LISTED BELOW.
 
INITIAL WIND RADII BASIS: PERSISTENCE
 
CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE 
NORTHEAST.
 
AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 117 KTS AT 300100Z
   CIMSS ADT: 129 KTS AT 300100Z
 
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
 
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW
 
3. FORECAST REASONING.
 
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
 
FORECAST DISCUSSION: TYPHOON KRATHON WILL CONTINUE TO STEADILY
INTENSIFY AND REACH PEAK INTENSITY WITHIN THE NEXT 12 HOURS. HOWEVER, 
FURTHER RAPID INTENSIFICATION IS UNLIKELY AS INDICATED BY UNANIMOUS 
INTENSITY GUIDELINES. AS KRATHON SLOWS DOWN, IT WILL BE FUELED BY 
SLIGHTLY COOLER WATER DUE TO UPWELLING AND WILL WEAKEN TO 110 KTS BY 
TAU 48, JUST PRIOR TO MAKING LANDFALL OVER SOUTHERN TAIWAN. AS THE 
SYSTEM PROGRESSES THROUGH THE CENTRAL MOUNTAIN RANGE OF THE ISLAND, 
THE TERRAIN INTERACTION WILL CAUSE FURTHER DETERIORATION OF THE CORE
AND THE WIND FIELD OF THE SYSTEM, LEADING TO INTENSITY BELOW 75 KTS
AS THE SYSTEM RE-EMERGES OVER THE WATERS OF EAST CHINA SEA BETWEEN
TAUS 72 AND 96. FURTHER WEAKENING IS FORECAST TOWARDS THE END OF
THE FORECAST PERIOD.
 
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN FAIR
AGREEMENT IN REGARD TO THE INITIAL TRACK OF TYPHOON 20W, WITH
MAJORITY OF THE SOLUTIONS FORECASTING THE BEGINNING OF THE
NORTHEASTWARD TURN JUST SOUTH OF TAIWAN. EXCLUDING NAVGEM AND
GALWEM THE CROSS-TRACK SPREAD BETWEEN THE MULTI-MODEL CONSENSUS
MEMBERS IS 42 NM JUST PRIOR TO LANDFALL. AS THE SYSTEM TRACKS OVER
TAIWAN IT IS CURRENTLY FORECAST TO REEMERGE OVER WATER, JUST EAST
OF TAIPEI, PAST TAU 72. SIGNIFICANT MODEL GUIDANCE UNCERTAINTY
EXISTS IN REGARD TO THE TRACK PAST TAU 96, WITH SOME MODELS
SUGGESTING A NORTHWESTWARD DIRECTION, WHILE OTHERS FORECAST MORE
NORTHERLY TRACK, DUE TO UNRESOLVED SIGNIFICANCE AND DOMINANCE OF
THE COMPETING STEERING MECHANISMS IN THE FORM OF UPPER-LEVEL TROUGH
OVER WESTERN JAPAN AND THE UPPER-LEVEL RIDGE OVER EASTERN CHINA.
IN TERMS OF INTENSITY GUIDELINES, JTWC FORECAST IS PLACED IN
CLOSED PROXIMITY TO THE MULTI-MODEL CONSENSUS, WHICH DOES NOT
INDICATE ANY SIGNIFICANT CHANCE OF RAPID INTENSIFICATION, AND PAST
TAU 12 SUGGESTS STEADY WEAKENING.
 
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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