WDPN31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.4N 142.8E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 500 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 39 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONTINUED
ROBUST STRUCTURE, WITH A 20 NM DIAMETER EYE SURROUNDED BY A NEARLY
SYMMETRIC RING OF DEEP CONVECTION. HOWEVER, INFRARED SATELLITE DATA
INDICATES THAT CLOUD TOPS IN THE NORTHWESTERN PORTION OF THE
EYEWALL HAVE WARMED A BIT, SUGGESTING THAT THE PREVIOUSLY OBSERVED
INTENSIFICATION TREND HAS ENDED. TY 07W IS ALSO BEGINNING TO LOSE
SUPPORT FROM AN UPPER-LEVEL LOW TO THE NORTH, WHICH IS RACING AWAY
FROM THE SYSTEM AND HAVING LESS OF AN APPARENT IMPACT ON THE
OUTFLOW PATTERN. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE CLEAR EYE EVIDENT IN VISIBLE AND MICROWAVE
SATELLITE IMAGERY. THE INITIAL INTENSITY OF 115 KTS IS ASSESSED
WITH HIGH CONFIDENCE BASED ON SUPPORTIVE, MULTI-AGENCY SUBJECTIVE
DVORAK AND UW-CIMSS OBJECTIVE SATELLITE INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND 110308Z
AMSR2-BASED WIND SPEED DATA

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 108 KTS AT 110600Z
   CIMSS ADT: 119 KTS AT 110530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST TRACK HAS SHIFTED
WESTWARD, IN LINE WITH SHIFTING OBJECTIVE GUIDANCE. THE PREDICTED
LANDFALL POINT IS COINCIDENTALLY LOCATED ABOUT 75 NM TO THE WEST OF
ITS LOCATION IN THE PREVIOUS WARNING. 

FORECAST DISCUSSION: TY 07W WILL TURN NORTHWESTWARD OVER THE NEXT
SIX TO TWELVE HOURS. THE PATTERN IS EXPECTED TO FAVOR RIDGE
BUILDING TO THE NORTHEAST, WITH THE MID-LATITUDE JET POSITIONED FAR
TO THE NORTH AND NO APPARENT INHIBITING FEATURES DEVELOPING IN THE
NEAR TERM. TY 07W IS EXPECTED TO FOLLOW THE RIDGE THROUGHOUT THE
FORECAST PERIOD, TURNING INCREASINGLY POLEWARD AFTER TAU 48 AND
BEGINNING TO ACCELERATE IN THE EXTENDED PERIOD. THE FEATURES
IMPACTING INTENSITY HAVE NOT CHANGED FROM THE PREVIOUS FORECAST.
DECLINING OCEAN HEAT CONTENT, CONTENTION WITH DRY AIR UPSTREAM, AND
REDUCED DIVERGENCE ALOFT ARE ALL EXPECTED TO DRIVE A WEAKENING
TREND. HOWEVER, NONE OF THESE FEATURES ARE EXPECTED TO BE IMPACTFUL 
ENOUGH TO WEAKEN THE SYSTEM BELOW TYPHOON INTENSITY PRIOR TO 
LANDFALL. IN THE EXTENDED RANGE, HOWEVER, PASSAGE OVER LAND AND 
INTERACTION WITH A DEVELOPING TROUGH TO THE NORTHWEST WILL CONTRIBUTE 
TO A MORE PRONOUNCED WEAKENING TREND AND INDUCE THE EARLY STAGE OF 
EXTRATROPICAL TRANSITION. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE, INCLUDING GLOBAL MODEL
ENSEMBLE SOLUTIONS, NOW FAVOR THE SCENARIO OF RIDGE BUILDING TO
THE NORTHEAST, AND TRACK GUIDANCE HAS SHIFTED WESTWARD AS A RESULT. 
THE CURRENT FORECAST IS CONSISTENT WITH THE SHIFT IN GUIDANCE AND 
LIES NEAR THE MULTI-MODEL CONSENSUS. SOLUTIONS LIE WITHIN A MOSTLY 
NARROW RANGE THROUGH TAU 72 BUT DIVERGE THEREAFTER DUE TO UNCERTAINTY 
REGARDING THE TIMING OF THE EXPECTED TURN TO THE NORTH AND POST-TURN 
TRACK SPEED. THEREFORE, CONFIDENCE IN THE TRACK FORECAST IS MEDIUM 
EARLY ON AND LOW IN THE EXTENDED PERIOD. INTENSITY FORECASTS ARE IN 
GOOD AGREEMENT THROUGH MOST OF THE FORECAST PERIOD, AND THE 
ENVIRONMENTAL FACTORS AT PLAY ARE FAIRLY STRAIGHTFORWARD, LENDING 
MEDIUM TO HIGH CONFIDENCE TO THE PREDICTED INTENSITY. 

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