WDPN31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (DAMREY) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.5N 155.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 190 NM SOUTH-SOUTHEAST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
TROPICAL STORM STRENGTH CIRCULATION APPEARING TO BE STRETCHED
LONGITUDINALLY AS THE UPPER LEVEL OUTFLOW TO THE NORTH CONTINUES TO
CRANK. THE WESTERN PERIPHERY OF THE CIRCULATION REMAINS MOSTLY
EXPOSED DUE TO THE SUBSIDENCE AND DRY AIR BEING PROVIDED BY THE
TROPICAL UPPER TROPOSPHERIC TROUGH TO THE SYSTEM NORTHWEST. A
RECENT 250846Z SCATTEROMETRY PASS REVEALED AN ASYMMETRIC WIND FIELD
WITH THE STRONGEST WINDS (35-40KTS) IN THE EASTERN QUADRANT WHILE
10-15KT WINDS DOMINATE THE WESTERN QUADRANT. THE INITIAL POSITION
IS PLACED WITH MEDIUM CONFIDENCE BASED ON EIR AND SCATTEROMERY
DATA. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON SCATTEROMERY DATA ALONG WITH PGTW AND KNES
DVORAK INTENSITY ESTIMATES INDICATING 45KTS, WHILE THE REAMING
GUIDANCE IS 10-15 KTS LOWER.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A NEAR
EQUATORIAL RIDGE (NER) CENTERED TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 42 KTS AT 251058Z
   CIMSS ADT: 33 KTS AT 251140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TS 08W (DAMREY) IS FORECAST TO CONTINUE
TRACKING GENERALLY NORTHWARD UNDER THE STEERING INFLUENCE OF THE
NER CENTERED TO THE SOUTHEAST. BY TAU 12 THE SYSTEM WILL SHIFT
STEERING TO A SUBTROPICAL RIDGE (STR) TO THE NORTH AND TRACK SPEEDS
WILL GRADUALLY INCREASE. BY TAU 48, 08W WILL APPROACH THE AXIS OF
THE STR AND TURN DUE NORTH, AS THE SYSTEM CONTINUES FURTHER INTO
THE SUBTROPICS, IT WILL INITIATE EXTRATROPICAL TRANSITION (ETT) BY
TAU 72 AND WILL COMPLETE ETT BY TAU 96. IN TERMS OF INTENSITY, OVER
THE NEXT 12 HOURS, AS 08W WILL MOVE EAST OF THE AFOREMENTIONED TUTT
CELL, WHICH IS ALREADY PROVIDING A TREMENDOUS POLEWARD OUTFLOW
CHANNEL, WHICH WILL CONTINUE TO FUEL THE SYSTEMS INTENSIFICATION TO
AN ESTIMATES 65KTS BY TAU 48, DESPITE MODERATE SHEAR VALUES. GFS IN
PARTICULAR INDICATES THAT THE TUTT CELL TO THE NORTHWEST COMBINED
WITH AN UPPER LEVEL ANTICYCLONE TO THE NORTHEAST WILL PROVIDE IN
EXCESS OF 95KTS OF SOUTHEASTERLY FLOW. THIS FORTUITOUS SETUP COULD
FUEL 08W FAR BEYOND THE ANTICIPATED PEAK INTENSITY OF 65KTS, THOUGH
THE EXACT PLACEMENT OF ALL THREE ATMOSPHERIC BODIES DURING THIS
PERIOD WILL DETERMINE THE EXACT PLACEMENT OF THE LLCC IN RELATION
TO THE JET MAX AND THUS SHEAR WILL DRIVE THE ULTIMATE INTENSITY.
THE SYSTEM WILL GRADUALLY WEAKEN BEYOND TAU 72 AS IT BEGINS ETT,
BUT IS STILL ANTICIPATED TO BECOME A STORM FORCE EXTRATROPICAL LOW
BY THE END OF THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH ALL
MEMBERS CLOSELY FOLLOWING THE JTWC FORECAST TRACK WITH MINIMAL
CROSS TRACK DEVIATION AND WORSENING ALONG TRACK DEVIATION WITH
RESPECT TO TIME. FOR THIS REASON THE JTWC FORECAST TRACK IS PLACED
WITH OVERALL MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE
IS IN POOR AGREEMENT WITH A FEW MEMBERS ROCKETING THE SYSTEM UP TO
70KTS BY TAU 48. THOUGH THERE IS A LARGE SPREAD BETWEEN THE MOST
AND LEAST AGGRESSIVE MEMBERS, THE GENERAL TREND OF THE JTWC
INTENSITY FORECAST IS ECHOED BY THE BULK OF THE MODELS. FOR THESE
REASON THE JTWC INTENSITY FORECAST IS PLACED INITIALLY WITH MEDIUM
CONFIDENCE AND WITH LOW CONFIDENCE THEREAFTER.

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