WDPN31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (MALOU) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.5N 138.7E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 349 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FRAGMENTED
BANDS OF MODERATE TO DEEP CONVECTION WRAPPING INTO THE ASSESSED LOW
LEVEL CIRCULATION CENTER (LLCC), THOUGH THE BULK OF THE CONVECTION
IS CONFINED TO THE EASTERN SEMICIRCLE OF THE BROAD CENTRAL
CIRCULATION. THE INITIAL POSITION IS ASSESSED WITH ONLY MEDIUM
CONFIDENCE DUE TO THE OBSCURATION OF THE LLCC BY HIGH-LEVEL
CLOUDINESS AND THE BROAD AND DISORGANIZED NATURE OF THE CIRCULATION
AS EVIDENCED IN EARLIER SCATTEROMETER IMAGERY. AGENCY AND OBJECTIVE
FIX POSITIONS ARE WIDELY SCATTERED ACROSS A 70-NM CIRCLE,
CONTRIBUTING TO THE UNCERTAINTY IN THE INITIAL POSITION. THE
INITIAL INTENSITY OF 50 KNOTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON A CONGRUENCE OF THE BULK OF THE AGENCY FIXES AND THE
OBJECTIVE ADT AND SATCON ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 52 KTS AT 260332Z
   CIMSS ADT: 51 KTS AT 260230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE INITIAL POSITION AS WELL AS PREVIOUS BEST
TRACK POSITIONS HAVE BEEN ADJUSTED ABOUT 50-NM FURTHER SOUTH BASED
ON 0000Z ASCAT DATA WHICH INDICATED A BROAD, AND SOMEWHAT
DISORGANIZED CIRCULATION HIDDEN BY A DENSE UPPER-LEVEL CIRRUS
SHIELD. BASED ON THE ADJUSTED TRACK POSITIONS, THE SYSTEM HAS
SIGNIFICANTLY SLOWED, IN RESPONSE TO THE DEVELOPMENT OF A WEAK
MESOSCALE, MID-LEVEL RIDGE TO THE NORTH. THIS RIDGE SHOULD WEAKEN
AND RETROGRADE OVER THE NEXT FEW HOURS, AND TS 25W IS EXPECTED TO
RESUME A NORTH-NORTHEASTWARD TRACK ALONG THE WESTERN PERIPHERY OF
THE LARGE DEEP-LAYER STR TO THE EAST. WATER VAPOR IMAGERY AND
ATMOSPHERIC MOTION VECTORS INDICATE THE PRESENCE OF A DEEP 200MB
TROUGH TO THE WEST, WHICH IS SERVING TO ENHANCE POLEWARD OUTFLOW.
INTENSITY GUIDANCE IS STARTING TO PICK UP ON THE IMPROVED OUTFLOW,
TRIGGERING THE RAPID INTENSIFICATION PREDICTION AID (RIPA) IN
RESPONSE TO QUICKLY IMPROVING OUTFLOW. ONCE THE LOW LEVEL
CIRCULATION CONSOLIDATES, THE SYSTEM IS EXPECTED TO QUICKLY
INTENSIFY TO A PEAK OF 80 KNOTS BY TAU 48. TS 25W WILL BEGIN TO
INTERACT WITH THE BAROCLINIC ZONE BETWEEN TAU 48 AND TAU 72 AS IT
MOVES OVER COOLER WATERS, ENCOUNTERS INCREASING VWS AND STARTS TO
ENTRAIN A COOLER, DRIER AIR MOVING QUICKLY SOUTHWARD FROM JAPAN.
THE SYSTEM WILL FULLY TRANSITION TO AN EXTRA-TROPICAL CYCLONE NO
LATER THAN TAU 96, AND POTENTIALLY AS EARLY AS TAU 72.   

MODEL DISCUSSION: TRACK GUIDANCE IS IN OVERALL GOOD AGREEMENT ON
THE OVERALL NORTH-NORTHEASTWARD TRACK THROUGH THE FORECAST PERIOD,
WITH CROSS-TRACK SPREAD LIMITED TO 110NM AT TAU 48 INCREASING TO
165NM AT TAU 96, WITH NAVGEM THE EASTERN OUTLIER. ALONG-TRACK
SPREAD INCREASES SIGNIFICANTLY AFTER TAU 72 AS THE SYSTEM
ACCELERATES WHILE UNDERGOING EXTRA-TROPICAL TRANSITION. THE JTWC
TRACK FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST AND
LIES SLIGHTLY WEST OF THE CONSENSUS MEAN THROUGH TAU 48, AND
SLIGHTLY SLOWER THAN THE MEAN THROUGH TAU 96. THE BULK OF THE
INTENSITY GUIDANCE REMAINS TIGHTLY CLUSTERED ABOUT THE MEAN, AND
THE JTWC FORECAST TRACKS THE CONSENSUS CLOSELY FOR THE DURATION OF
THE FORECAST. AS PREVIOUSLY MENTIONED, THE RIPA GUIDANCE HAS
TRIGGERED ON THIS RUN, INDICATING A PEAK INTENSITY OF 100 KNOTS BY
TAU 48, WHICH IS OVER 20 KNOTS HIGHER THAN THE CONSENSUS MEAN AND
THE INDIVIDUAL INTENSITY GUIDANCE MEMBERS. WHILE THE ENVIRONMENT IS
FAVORABLE FOR DEVELOPMENT, THE BROAD NATURE OF THE CIRCULATION AND
LACK OF A WELL-DEFINED CONVECTIVE CORE ARGUE AGAINST NEAR-TERM
RAPID INTENSIFICATION TO THE DEGREE THAT RIPA IS INDICATING.   

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