WDPN31 PGTW 082100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 03W (GUCHOL) WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.9N 130.4E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 560 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 40 NM
DIAMETER RAGGED EYE THAT CONTINUES TO HAVE MID TO UPPER-LEVEL CLOUD
DEBRIS CIRCULATING INSIDE IT. A 1658Z AMSR2 MICROWAVE PASS SHOWED
THAT THE EYEWALL IS MORE CLOSED THAN IT HAS BEEN IN THE PAST 12
HOURS, BUT REMAINS WEAK IN THE NORTHWEST QUADRANT. UPPER-LEVEL
OUTFLOW IS BEGINNING TO BE SUPPRESSED SOMEWHAT ON THE NORTHERN SIDE
DUE TO A BUILDING UPPER-LEVEL RIDGE OVER TAIWAN. THE INITIAL
INTENSITY IS HELD STEADY AT 80 KT BASED ON THE LOWER END OF
SUBJECTIVE DVORAK ESTIMATES. THE SATELLITE PRESENTATION HAS NOT 
IMPROVED SIGNIFICANTLY IN THE PAST 6 HOURS.

INITIAL WIND RADII BASIS: SAR AND SMOS

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 67 KTS AT 081642Z
   CIMSS ADT: 102 KTS AT 081730Z

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

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: TYPHOON 03W (GUCHOL) IS IN THE PROCESS OF
MAKING A SLOW TURN NORTHWARD AROUND THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE TO ITS NORTHEAST. A NORTHEASTWARD HEADING AND
ACCELERATING FORWARD MOTION IS EXPECTED AFTER 48 HOURS AS GUCHOL
APPROACHES THE MID-LATITUDE WESTERLIES. IN THE SHORT TERM, THE
NORTHWESTWARD TO NORTHWARD TRACK WILL TAKE GUCHOL OUT OF THE DEEP,
WARM WATER IT HAS BEEN TRACKING OVER, AND INTO THE AREA THAT
TYPHOON 02W RECENTLY TRACKED OVER, LEAVING A COLD WAKE BEHIND IT.
TYPHOON 03W (GUCHOL) IS ALREADY BEGINNING TO MOVE OVER THIS AREA OF
COOLER WATER WITH A SHALLOWER WARM LAYER, AND THIS IS LIKELY TO PUT
A CEILING ON ITS INTENSITY FAIRLY SOON. SOME ADDITIONAL
STRENGTHENING IS POSSIBLE DURING THE NEXT 12 HOURS, AND THE JTWC
FORECAST SHOWS A PEAK OF 90 KT DURING THE 12-24 HOUR PERIOD, A
LITTLE LOWER THAN THE PREVIOUS FORECAST. THEREAFTER, OCEANIC
CONDITIONS AND AN UPTICK IN VERTICAL WIND SHEAR ARE LIKELY TO
INDUCE GRADUAL WEAKENING. AFTER 72 HOURS, GUCHOL WILL PASS OVER
WATERS COLDER THAN 26 DEGREES CELSIUS, AND IS EXPECTED TO
TRANSITION INTO A SUBTROPICAL CYCLONE BY 120 HOURS AS IT CONTINUES
TO TRACK SOUTH OF THE MID-LATITUDE JET STREAM.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH
72 HOURS, AND HAS TIGHTENED IN THE 72-120 HOUR RANGE SINCE THE
PREVIOUS FORECAST. CONFIDENCE IS GENERALLY HIGH IN THIS FORECAST,
THOUGH SOME UNCERTAINTY REMAINS BEYOND 72 HOURS AS GUCHOL
APPROACHES THE MID-LATITUDE JET IN A WAY THAT MAKES ITS EXACT
FORWARD SPEED A LITTLE UNCERTAIN. THE JTWC FORECAST IS SLIGHTLY TO
THE RIGHT OF THE MULTI-MODEL CONSENSUS, CLOSER TO THE ECMWF, GFS,
AND GFS ENSEMBLE GROUPING OF MODELS. THE JTWC INTENSITY FORECAST IS
CLOSE TO THE MULTI-MODEL CONSENSUS THROUGHOUT THE FORECAST PERIOD.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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