WDPN31 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SEPAT) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.0N 140.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 198 NM NORTH-NORTHWEST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 02W WITH EXPOSED LOW-LEVEL CLOUD BANDS IN THE NORTHERN
PERIPHERY OF THE SYSTEM AND DEEP CONVECTION SHEARED TO THE SOUTH.
WATER VAPOR IMAGERY REVEALS COMPETING VERTICAL WIND SHEAR IMPOSING
ON TS 02W BETWEEN AN UPPER-LEVEL TROUGH TO THE NORTH AND A TROPICAL
UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE SOUTHWEST. THE SHALLOW
NATURE OF TS 02W IS HIGHLIGHTED IN 240341Z N-20 ATMS 89GHZ
MICROWAVE IMAGE REVEALING LOW-LEVEL CLOUD BANDING WRAPPING INTO THE
CIRCULATION CENTER. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED CLOUD BANDING HIGHLIGHTED IN
ANIMATED MSI. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH LOW
CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) TO THE
EAST-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 44 KTS AT 240318Z
   CIMSS ADT: 43 KTS AT 240530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 24-25 CELSIUS
   OUTFLOW: STRONG WESTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 02W WILL CONTINUE TO TRACK NORTHWESTWARD
FOR THE NEXT 24 HOURS WHILE UNDER THE STEERING INFLUENCE OF THE STR TO 
THE NORTHEAST. BY TAU 24, THE SYSTEM WILL HAVE CROSSED THE RIDGE AXIS 
AND TRANSITION TO A NORTHEASTERLY TRACK FOR THE REMAINDER OF THE 
FORECAST PERIOD. THE SYSTEM WILL BEGIN EXTRATROPICAL TRANSITION AFTER 
CROSSING INTO COOL SEA SURFACE TEMPERATURES BETWEEN TAU 24-36, AND 
BECOME INCREASINGLY BAROCLINIC AS AN UPPER-LEVEL TROUGH APPROACHES 
FROM THE WEST. TS 02W IS FORECAST TO WEAKEN TO 30KTS DURING THE FIRST 
24 HOURS OF THE FORECAST DUE TO STRONG VERTICAL WIND SHEAR FROM THE
APPROACHING UPPER-LEVEL TROUGH. HOWEVER, BAROCLINIC FORCING WILL
ALLOW THE SYSTEM TO SLIGHTLY INTENSIFY TO 35KTS BY TAU 36 AS
EXTRATROPICAL TRANSITION COMMENCES. THE SYSTEM IS ANTICIPATED TO
MAINTAIN AN INTENSITY OF 35KTS FOR THE REMAINDER OF THE FORECAST
PERIOD. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN STRONG
AGREEMENT THAT THE SYSTEM WILL ROUND THE STR TO THE NORTHEAST, BUT
THE TRACK SPEED VARIES SLIGHTLY BETWEEN THE JTWC CONSENSUS MEMBERS.
THE TWO PRIMARY OUTLIERS ARE NAVGEM AND GALWEM, WHICH REFLECT
TRACKS LYING WEST OF CONSENSUS. THE ALONG-TRACK SPEEDS VARY
SLIGHTLY WITH GFS LYING 100NM BEHIND ECMWF BY THE END OF THE
FORECAST PERIOD. THE INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT,
INDICATING A CONSISTENT INTENSITY BETWEEN 30-35TS FOR THE REMAINDER
OF THE FORECAST PERIOD.

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