WDPN31 PGTW 260300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (KULAP)            
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.8N 143.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 163 NM SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 19W HAS CONTINUED TO STEADILY CONSOLIDATE AS 
INDICATED IN ANIMATED ENHANCED INFRARED SATELLITE IMAGERY, WHICH 
SHOWS DEEP CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE WRAPPING 
INTO THE NORTHERN QUADRANT. A 260024Z MHS 89GHZ MICROWAVE IMAGE 
PROVIDES CLEAR EVIDENCE THAT A DEFINED LOW-LEVEL CIRCULATION CENTER 
HAS FORMED WITH EXTENSIVE DEEP CONVECTIVE BANDING LOCATED OVER THE 
EASTERN SEMICIRCLE. ADDITIONALLY, A 260028Z ASCAT-B BULLSEYE IMAGE 
SHOWS A SYMMETRIC CIRCULATION WITH A SWATH OF 30-35 KNOT WINDS OVER 
THE EASTERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL POSITION AND 
INITIAL INTENSITY WITH HIGH CONFIDENCE. ENVIRONMENTAL CONDITIONS ARE 
FAVORABLE WITH ROBUST EQUATORWARD AND POLEWARD OUTFLOW CHANNELS AND 
LOW VERTICAL WIND SHEAR (VWS). 

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: COMBINED STEERING INFLUENCE WITH A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND A WEAK STR 
TO THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 36 KTS AT 252159Z
   CIMSS ADT: 35 KTS AT 260140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TS 19W IS FORECAST TO TRACK GENERALLY 
NORTHWESTWARD THROUGH TAU 24 WITHIN THE COMBINED STEERING INFLUENCE 
OF THE BROAD STR TO THE EAST AND THE WEAK STR POSITIONED TO THE 
NORTH. AFTER TAU 24, A DEEP MIDLATITUDE SHORTWAVE TROUGH WILL 
APPROACH CENTRAL JAPAN AND WEAKEN THE STR TO THE NORTH ALLOWING THE 
SYSTEM TO TURN POLEWARD THROUGH TAU 36 THEN RECURVE NORTHEASTWARD 
ALONG THE NORTHWESTERN FLANK OF THE RE-ORIENTED STR TO THE SOUTHEAST. 
BY TAU 48, TS 19W WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT 
INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE. THE 
SYSTEM WILL COMPLETE ETT BY TAU 72 AS IT GAINS FRONTAL 
CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE 
WESTERLIES. TS 19W SHOULD INTENSIFY STEADILY THROUGH TAU 48 UNDER 
FAVORABLE CONDITIONS TO A PEAK OF 70 KNOTS. AFTER TAU 48, COOLER SEA 
SURFACE TEMPERATURE VALUES (26C) AND MODERATE VWS WILL WEAKEN THE 
SYSTEM. HOWEVER, THE SYSTEM IS EXPECTED TO REMAIN A LARGE STORM-FORCE 
EXTRA-TROPICAL LOW.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH 
A SPREAD OF LESS THAN 90NM THROUGH TAU 48. AFTER TAU 48, MODEL 
GUIDANCE DIVERGES SLIGHTLY WITH NAVGEM THE PRIMARY OUTLIER OVER THE 
SOUTHERN EDGE OF THE AIDS ENVELOPE. THE REMAINDER OF THE GUIDANCE IS 
IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH OVERALL CONFIDENCE IN THE 
JTWC FORECAST TRACK. ADDITIONALLY, THE 251800Z ECMWF ENSEMBLE (EPS) 
AND GFS ENSEMBLE (GEFS) ARE IN GOOD AGREEMENT SUPPORTING THE JTWC 
FORECAST TRACK. THE 251800Z COAMPS-TC ENSEMBLE INDICATES A MODERATE 
PROBABILITY (40 TO 60 PERCENT) FOR RAPID INTENSIFICATION PEAKING IN 
THE TAU 36 TO TAU 60 TIMEFRAME.  

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