WDPN31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.2N 140.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 606 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS BUILDING
DEEP CONVECTION OVER A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC). STRONG (15-20KST) VERTICAL WIND SHEAR FROM THE
NORTHWEST HAS SLIGHTLY DISLOCATED THE DEEP CONVECTION TO THE
SOUTHEAST OF THE CENTER. WATER VAPOR IMAGERY REVEALS MODERATE
EQUATORWARD OUTFLOW AND AN OVERALL MOIST ENVIRONMENT. THIS SYSTEM HAS
REMAINED QUASI-STATIONARY OVER THE LAST SIX HOURS. AN 111640Z
NOAA-21 ATMS 88GHZ MICROWAVE IMAGE REINFORCES THE DISLOCATED NATURE
OF THE CONVECTION TO THE SOUTHEAST OF TROPICAL STORM (TS) 06W. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED ANIMATED EIR AND MICROWAVE IMAGERY. 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 CONFUSED AND WEAK STEERING
ENVIRONMENT BETWEEN AN ELONGATED RIDGE TO THE SOUTH AND A WEAK
SUBTROPICAL RIDGE TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 36 KTS AT 111638Z
   CIMSS ADT: 33 KTS AT 111730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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 06W WILL REMAIN IN A WEAK STEERING
ENVIRONMENT FOR THE FIRST 24 HOURS OF THE FORECAST PERIOD. DURING
THIS TIME, TS 06W WILL REMAIN SLOW AND QUASI-STATIONARY,
POTENTIALLY RESULTING IN IRREGULAR MOTION. THE SUBTROPICAL RIDGE TO
THE NORTHEAST WILL BUILD OVER THE FIRST 36 HOURS OF THE FORECAST,
ALLOWING FOR FASTER MOVEMENT NORTH-NORTHEASTWARD. BETWEEN TAU
36-48, THE TRACK MOTION WILL BE STEERED NEARLY NORTHWARD FOR THE
REMAINDER OF THE FORECAST PERIOD. THE SYSTEM WILL REMAIN TROPICAL
UNTIL TAU 48, WHEN TS 06W BEGINS EXTRATROPICAL TRANSITION. A
LONGWAVE TROUGH WILL CAUSE THE SYSTEM TO BECOME BAROCLINIC, AND THE
SYSTEM WILL LOSE THE FAVORABLE HEAT SOURCE OF WARM SEA SURFACE
TEMPERATURES (SST) BETWEEN TAU 48-72. EXTRATROPICAL TRANSITION IS
ANTICIPATED TO BE COMPLETED BY TAU 72. TS 06W WILL STRUGGLE TO
INTENSIFY OVER THE FIRST 36 HOURS OF THE FORECAST WHILE IN A
HIGH-SHEAR ENVIRONMENT. ONCE SHEAR DECREASES, THE SYSTEM WILL
GRADUALLY INTENSIFY TO A PEAK OF 55KTS BY TAU 48. SLIGHT WEAKENING
TO 45KTS IS ANTICIPATED AS THE SYSTEM BECOMES EXTRATROPICAL.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE HAS A LARGE SPREAD
AT THE END OF THE FORECAST PERIOD, WITH GALWEM LYING SIGNIFICANTLY
FAR TO THE WEST OF THE MAIN BULK OF THE JTWC MULTI-MODEL CONSENSUS
MEMBERS. THE COMPLETE TRACK SPREAD BY TAU 72 IS 560NM. THE
INTENSITY GUIDANCE REPRESENTS SLOW INTENSIFICATION IN THE EARLY
TERM FORECAST, BUT BEGINS TO SPREAD AFTER TAU 36. THE PEAK
INTENSITY SPREAD IS 20KTS BETWEEN 45-65KTS AT TAU 48.

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