WDPN31 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (KULAP) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.8N 141.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 123 NM NORTH-NORTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SLOWLY
CONSOLIDATING SYSTEM WITH CONVECTIVE FEEDER BANDS ON THE EASTERN
PERIPHERY WRAPPING INTO A RAGGED LOW LEVEL CIRCULATION CENTER
(LLCC). A 261906Z SSMIS 91 GHZ MICROWAVE IMAGE REVEALS DEEP
CONVECTIVE BANDING OVER THE NORTHERN QUADRANTS WRAPPING INTO A LOW
LEVEL CIRCULATION CENTER POSITIONED ALONG THE SOUTHWESTERN EDGE OF
A CURVED CONVECTIVE BAND. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON EIR IMAGERY AND THE SSMIS MICROWAVE
IMAGERY. THE INITIAL INTENSITY IS ALSO PLACED WITH MEDIUM IS BASED
A BLEND OF AUTOMATED DVORAK ESTIMATES INTENSITIES FROM CMISS ADT
WHICH SHOW 41 KNOTS, WHILE SATCON SHOWS UP TO 45 KNOTS. WITH AGENCY
DVORAK INTENSITIES FROM PGTW T2.5, RJTD T3.0, AND KNES T3.5.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 45 KTS AT 261619Z
   CIMSS ADT: 41 KTS AT 261740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   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 19W (KULAP) IS FORECAST TO
TRACK GENERALLY POLEWARD ALONG THE OUTER PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST, AS THE SYSTEM CONTINUES
TO DO SO IT WILL ROUND THE RIDGE AXIS WITHIN THE NEXT 12 HOURS. AS
THIS OCCURS, A SHORTWAVE TROUGH WILL WEAKEN THE STR ALLOWING 19W TO
RECURVE AND ACCELERATE NORTHEASTWARD. AS THE SYSTEM TRANSITS
NORTHEASTWARD, THE ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE
FOR 19W INTENSIFY TO A MAXIMUM INTENSITY OF 70 KTS BY TAU 48. AFTER
TAU 48, 19W WILL BEGIN TO INTERACT WITH THE SHORTWAVE TROUGH AND
BEGIN TO BECOME EMBEDDED IN THE MID-LATITUDE WESTERLIES AND
BAROCLINIC ZONE. BY TAU 72, THE SYSTEM WILL COMPLETE EXTRA-TROPICAL
TRANSITION (ETT) AS IT GAINS FRONTAL CHARACTERISTICS WHILE
DECREASING IN INTENSITY DUE TO COOLER SEA SURFACE TEMPERATURE
VALUES (25-26C) AND STRONG VERTICAL WIND SHEAR.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE ARE IN VERY GOOD THROUGH
TAU 36, WITH ONLY A 50 NM SPREAD IN MODEL TRACK SOLUTIONS. WITH A
GRADUAL SPREAD IN CROSS TRACK UNCERTAINTY TO 320NM BY TAU 72.
THEREFORE, THE JTWC TRACK FORECAST REMAINS GENERALLY HIGH THROUGH
OUT THE FORECAST PERIOD. THE INTENSITY FORECAST IS ASSESSED WITH
MEDIUM CONFIDENCE WITH GFS DECAY SHIPS (DSHA) REPRESENTING THE LOW
END OF GUIDANCE WITH A PEAK OF 55 KNOTS BY TAU 36, AND THE GFS
(AHNI) AND HWRF INDICATING A PEAK OF 75 KNOTS. 

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