WDPN31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (MALOU) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.1N 138.6E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 374 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD,
ELONGATED CIRCULATION WITH DEEP CONVECTIVE BANDING WRAPPING IN FROM
THE SOUTH AND A DEVELOPING OUTFLOW CHANNEL TO THE NORTH. THE INITIAL
INTENSITY IS BASED ON A 250844Z SMAP IMAGE SHOWING 37-40 KT WINDS
IN THE NORTHEASTERN QUADRANT OF THE CIRCULATION. THE INITIAL
POSITION IS BASED ON THE WRAPPING OF THE NORTHERN CONVECTIVE BAND
IN A 25904Z 91GHZ SSMIS IMAGE AND IS SUPPORTED BY THE PGTW POSITION
FIX.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A BUILDING
SUBTROPICAL RIDGE POSITIONED TO THE EAST-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 42 KTS AT 250930Z
   CIMSS ADT: 32 KTS AT 251140Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM 25W WILL CONTINUE TO TRACK
NORTH-NORTHEASTWARD UNTIL ABOUT TAU 48, AT WHICH POINT IT WILL
BEGIN TO ROUND THE SUBTROPICAL RIDGE AXIS AND ACCELERATE TO THE
NORTHEAST IN THE WAKE OF A MIDLATITUDE LOW PRESSURE SYSTEM. TS 25W
WILL REMAIN IN A FAVORABLE ENVIRONMENT UNTIL ABOUT TAU 72, ALLOWING
FOR A PEAK INTENSITY OF 80 KTS AT THAT TIME. AFTERWARDS, COOLING
SEA SURFACE TEMPERATURES AND INCREASING VERTICAL WIND SHEAR WILL
BEGIN TO WEAKEN THE SYSTEM AS IT BEGINS EXTRATROPICAL TRANSITION
(ETT). IT IS EXPECTED TO COMPLETE ETT BY TAU 96 AS IT BECOMES
FURTHER EMBEDDED IN THE BAROCLINIC ZONE AND WEAKENS TO 65 KTS.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT IN REGARDS
TO FORECAST TRACK WITH ALL MODELS DEPICTING A GENERALLY
NORTH-NORTHEASTWARD TRACK FOLLOWED BY A TURN TO THE NORTHEAST
AROUND TAU 48. AT TAU 96, THE CROSS-TRACK SPREAD IS 140NM. HOWEVER,
THE MODELS ARE IN DISAGREEMENT IN REGARDS TO TRACK SPEED, AS EACH
MODEL BEGINS TO ACCELERATE THE SYSTEM INTO THE BAROCLINIC ZONE AT
DIFFERENT TIMES. NUMERICAL MODELS ARE IN GOOD AGREEMENT IN REGARDS
TO THE INTENSITY GUIDANCE WITH MOST MODELS SHOWING A PERIOD OF
STEADY INTENSIFICATION PEAKING AROUND TAU 72 AT ABOUT 70-85 KTS
FOLLOWED BY A WEAKENING TREND FOR THE REMAINDER OF THE FORECAST.
THE EXCEPTION IS COTI WHICH BEGINS TO WEAKEN THE STORM MUCH EARLIER
AT TAU 36. 

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