WDPN31 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (DAMREY) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 155.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 262 NM SOUTH-SOUTHEAST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS IMPROVED
DEEP CONVECTIVE BANDING WRAPPING INTO A DISCRETE CIRCULATION
CENTER. A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL CENTERED
TO THE NORTHWEST IS BOTH ENHANCING THE OUTFLOW OF THE EASTERN
PORTION OF 08W AND INTRODUCING DRY COOL AIR ALONG WITH ELEVATED
VERTICAL WIND SHEAR INTO THE WESTERN PORTION. A 250456Z SSMIS 91GHZ
COLOR COMPOSITE MICROWAVE IMAGE INDICATES A NEARLY COMPLETE
MICROWAVE EYE WITH TIGHTLY WRAPPING LOW LEVEL CLOUD LINES EVIDENT
BENEATH. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY DVORAK INTENSITY
ESTIMATES ALL INDICATING 45KTS WHILE AUTOMATED INTENSITY ESTIMATES
LAG SLIGHTLY BEHIND (33-44KTS).

INITIAL WIND RADII BASIS: PERSISTENCE 

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: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 37 KTS AT 250217Z
   CIMSS ADT: 34 KTS AT 250530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: TUTT CELL TO THE NORTHWEST PROVIDING VIGOROUS
POLEWARD OUTFLOW

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TS 08W (DAMREY) IS FORECAST TO CONTINUE
TRACKING GENERALLY NORTH-NORTHEASTWARD AND EVENTUALLY NORTHWARD
UNDER THE STEERING INFLUENCE OF THE NER CENTERED TO THE SOUTHEAST.
BY TAU 24 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 MOVES
EAST OF THE AFOREMENTIONED TUTT CELL, PROVIDING A TREMENDOUS
POLEWARD OUTFLOW CHANNEL, WHICH WILL 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 SEVERAL MEMBERS ALONG WITH RAPID
INTENSIFICATION (RI) AIDS ROCKETING THE SYSTEM UP TO 70KTS BY TAU
36. 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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