WDPN31 PGTW 261500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (MALOU) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 139.0E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 309 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A STEADILY
IMPROVING CONVECTIVE STRUCTURE, WITH BANDS OF DEEP CONVECTION NOW
WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC) WHEN EARLIER
THEY WERE RESTRICTED TO THE EASTERN SEMICIRCLE. A 261054Z ASCAT-A
PASS INDICATED THAT THE LLCC HAS SHRUNK AND BECOME MORE ORGANIZED,
THOUGH IT REMAINS SLIGHTLY ELONGATED. THE BULK OF THE CONVECTION
HOWEVER IS DISPLACED TO THE NORTHEAST UNDER 10-15 KNOTS
SOUTHWESTERLY SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON EXTRAPOLATION OF THE PREVIOUSLY MENTIONED ASCAT
PASS. THE INITIAL INTENSITY OF 55 KNOTS IS ASSESSED WITH MEDIUM
CONFIDENCE, HEDGED SLIGHTLY HIGHER THAN THE MAJORITY OF AGENCY
FIXES AND THE ADT, BASED ON THE SCATTEROMETER PASS WHICH SHOWED
50-55 KNOT WINDS IN THE NORTHEAST QUADRANT OF THE SYSTEM. A STRONG
MID-LATITUDE LOW PRESSURE SYSTEM AND ACCOMPANYING UPPER-LEVEL
TROUGH IS PROVIDING A KICK TO THE ALREADY STRONG POLEWARD OUTFLOW
CHANNEL, WITH ANIMATED WATER VAPOR IMAGERY SHOWING A ROBUST OUTFLOW
CHANNEL EXTENDING UP TO 40 NORTH.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 49 KTS AT 261130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: MODERATE EQUATORWARD OUTFLOW. 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING. HOWEVER, THE FORECAST HAS
BEEN SHORTENED TO 72 HOURS. 

FORECAST DISCUSSION: TS 26W IS TRACKING JUST A BIT EAST OF DUE
NORTH AT THE MOMENT, AND IS EXPECTED TO SLOWLY TACK OVER TO A
NORTHEASTWARD TRACK, ALONG THE WESTERN SIDE OF THE DEEP STR TO THE
EAST THROUGH THE DURATION OF THE FORECAST. TS 26W HAS STEADILY
CONSOLIDATED OVER THE PAST SIX HOURS, WITH THE LLCC SHRINKING AND
BECOMING MORE ORGANIZED BASED ON THE ASCAT DATA. WHILE THE
STRUCTURE IS IMPROVING THE CONVECTIVE CORE IS STILL STRUGGLING
AGAINST 10-15 KNOT SOUTHWESTERLY SHEAR, AND THUS THE SYSTEM HAS NOT
INTENSIFIED MUCH SINCE THE PREVIOUS ANALYSIS. UNDER OTHERWISE
FAVORABLE CONDITIONS OF WARM SSTS, LOW TO MODERATE VWS AND ROBUST
POLEWARD OUTFLOW, THE ONLY HINDRANCE TO RAPID DEVELOPMENT IS THE
CONSOLIDATION OF A VERTICALLY STACKED CORE. THUS, THE FORECAST
CALLS FOR STEADY INTENSIFICATION TO A PEAK OF 75 KNOTS BY TAU 48.
JUST AFTER TAU 48 THE SYSTEM WILL CROSS THE 26C ISOTHERM INTO MUCH
COOLER WATERS, WHICH COMBINED WITH RAPIDLY INCREASING VWS AND DRY,
COOL AIR ENTRAINMENT, WILL LEAD TO A RAPID WEAKENING TREND.
SIMULTANEOUSLY WITH REACHING PEAK INTENSITY, THE SYSTEM WILL BEGIN
TO THE EXTRA-TROPICAL TRANSITION (ETT) PROCESS AS IT BEGINS TO FEEL
THE EFFECTS OF WEAK THERMAL ADVECTION. TS 26W WILL COMPLETE ETT BY
TAU 72 AS A TYPHOON STRENGTH EXTRA-TROPICAL LOW PRESSURE SYSTEM AS
IT MOVES UNDER THE 200MB JET STREAM, BECOMES EMBEDDED UNDER A 500MB
TROUGH AND DEVELOPS FRONTAL CHARACTERISTICS.   

MODEL DISCUSSION: TRACK GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH
THE FORECAST, WITH CROSS-TRACK SPREAD OF 85NM AT TAU 72.
ALONG-TRACK SPREAD UNSURPRISINGLY INCREASES AFTER TAU 48 AS THE
SYSTEM UNDERGOES ETT AND ACCELERATES NORTHEASTWARD, BUT STILL
REMAINS RELATIVELY MODEST. THE JTWC FORECAST REMAINS CONSISTENT
WITH THE PREVIOUS TRACK, SLIGHTLY WEST OF THE CONSENSUS MEAN
THROUGH THE FORECAST, AND SLIGHTLY FASTER THAN THE MEAN AFTER TAU
48, WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT,
WITH ALL CONSENSUS MEMBERS NOW COMING INTO AGREEMENT ON A SLIGHTLY
LOWER PEAK INTENSITY. THE JTWC FORECAST CLOSELY TRACKS THE
CONSENSUS MEAN, AND WITHIN THE TIGHT GROUPING OF THE INDIVIDUAL
MEMBERS, WITH HIGH CONFIDENCE.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH//
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