WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.2N 140.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 50 NM WEST-NORTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: EASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS BUILDING
CONVECTION OVER A PARTIALLY OBSCURED LOW LEVEL CIRCULATION CENTER
(LLCC). DEEP CONVECTION IS SHEARED TO THE SOUTHEAST BY
NORTHWESTERLY STRONG (15-20KTS) VERTICAL WIND SHEAR. WATER VAPOR
IMAGERY REVEALS STRONG EQUATORWARD OUTFLOW ALOFT. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED
ANIMATED MSI REVEALING THE LLCC. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON A 120200Z METOP-B ASCAT PASS
THAT REVEALS 35KT WINDS IN THE SOUTHEASTERN QUADRANT WHILE
SUPPLEMENTED BY THE OBJECTIVE AND AGENCY FIXES BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: CURRENTLY IN A WEAK STEERING
ENVIRONMENT WITH A NEAR EQUATORIAL RIDGE TO THE SOUTH AND A WEAK
SUBTROPICAL RIDGE TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 33 KTS AT 112030Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 06W IS IN A WEAK STEERING
ENVIRONMENT FOR THE FIRST 24 HOURS OF THE FORECAST, GENERALLY
TRACKING TOWARDS THE NORTHEAST. BETWEEN TAU 24-36, THE SUBTROPICAL
RIDGE TO THE EAST WILL BUILD, DRIVING TS 06W NORTHWARD THROUGH TAU
48. AT TAU 48, 06W WILL CURVE NORTH-NORTHEASTWARD ON THE NORTHWEST
PERIPHERY OF THE SUBTROPICAL RIDGE. EXTRATROPICAL TRANSITION WILL
START AT TAU 48 DUE TO AN UPPER-LEVEL TROUGH CAUSING THE SYSTEM TO
BECOME BAROCLINIC. TS 06W WILL BE FULLY EXTRATROPICAL BY TAU 72,
WITH AN UPPER-LEVEL CYCLONE AND IN COOL SEA SURFACE TEMPERATURES.
THE HIGH SHEAR ENVIRONMENT WILL HINDER INTENSIFICATION DURING THE
FIRST 36 HOURS OF THE FORECAST. AFTER SHEAR DECREASES, TS 06W WILL
PEAK AT 55KTS AT TAU 48. SLIGHT WEAKENING WILL OCCUR AS THE SYSTEM
UNDERGOES EXTRATROPICAL TRANSITION, REACHING 45KTS AT THE END OF
THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD
AGREEMENT, WITH THE EXCEPTION OF GALWEM AND UKMET LYING TO THE WEST
OF THE CONSENSUS MEAN. JTWC FORECAST TRACK ALIGNS WITH THE BULK OF
THE MULTI-MODEL CONSENSUS GUIDANCE. INTENSITY AIDS ARE IN GOOD
AGREEMENT WITH A PEAK INTENSITY BETWEEN 45-65KTS. THE INTENSITY
GUIDANCE IS ALSO IN GOOD AGREEMENT ABOUT THE GRADUAL
INTENSIFICATION OF TS 06W IN THE EARLY TERM FORECAST AND THE
WEAKENING AS THE SYSTEM UNDERGOES EXTRATROPICAL TRANSITION.

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