WDPN31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W (GUCHOL) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.7N 132.4E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 476 NM NORTH-NORTHWEST OF KAYANGEL
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A DEEP
CONVECTIVE CLOUD STRUCTURE WITH SPIRAL CONVECTIVE BANDING TO THE
SOUTH WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A TIGHT
GROUPING OF AGENCY POSITION FIXES. THE INITIAL INTENSITY REMAINS 60
KT BASED ON A COMBINATION OF OBJECTIVE AND SUBJECTIVE DVORAK
INTENSITY ESTIMATES RANGING FROM T3.0 (45 KTS) TO T4.0 (65 KTS).
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH MODERATE EASTWARD
OUTFLOW AND LOW VERTICAL WIND SHEAR (VWS) AS WELL AS WARM SEA
SURFACE TEMPERATURES (SSTS) AND HIGH OCEAN HEAT CONTENT (OHC).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: AN EXTENSION OF THE SUBTROPICAL RIDGE
(STR) TO THE NORTH AND A NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 57 KTS AT 071700Z
   CIMSS ADT: 57 KTS AT 071740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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: TS 03W IS FORECAST TO TRACK WEST-NORTHWEST
THEN TRACK NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERIES OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTH AND A NEAR-EQUATORIAL RIDGE
(NER) TO THE SOUTH, WITH AN INCREASING INFLUENCE ON THE STEERING
FLOW THROUGH TAU 24. AFTER TAU 24, TS 03W IS EXPECTED TO TURN AND
TRACK NORTH-NORTHWESTWARD, AS A MAJOR SHORTWAVE TROUGH MOVING OVER
JAPAN WILL CREATE A BREAK IN THE STR TO THE NORTH. ADDITIONALLY, A
STR NEAR 30N 160E IS EXPECTED TO AMPLIFY AND BUILD. AS A RESULT,
THE SYSTEM WILL RAPIDLY TURN POLEWARD AND ACCELERATE NORTHEASTWARD
ALONG THE WESTERN PERIPHERY OF THE STR THROUGHOUT THE FORECAST. TS
03W WILL CONTINUE TO CONSOLIDATE FURTHER AND RAPIDLY INTENSIFY OVER
THE NEXT 36 HOURS, UNDER FAVORABLE CONDITIONS CHARACTERIZED BY
ROBUST OUTFLOW, LOW VWS, WARM SSTS. THIS WILL ALLOW THE SYSTEM TO
REACH A PEAK INTENSITY OF NEAR 90 KNOTS AT TAU 36. AFTER TAU 36, A
COMBINATION OF COOLER SSTS, INCREASING NORTHWESTERLY VWS, AND
CONSTRICTED OUTFLOW ALOFT, WILL COMBINED TO SLOWLY WEAKEN THE
SYSTEM. BY TAU 120 THE SYSTEM IS EXPECTED TO BEGIN SUBTROPICAL
TRANSITION.


MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE REMAINS
IN OVERALL GOOD AGREEMENT ON THE OVERALL RECURVE SCENARIO BUT SHOWS
HIGH UNCERTAINTY IN THE LATER TAUS. THE JTWC TRACK FORECAST IS
CLOSE TO THE MULTI-MODEL CONSENSUS THROUGH 36 HOURS WITH HIGH
CONFIDENCE AS THERE IS ONLY A 70 NM SPREAD IN MANY OF THE CONSENSUS
MEMBERS. AFTER TAU 36, MODEL SPREAD INCREASES WITH GFS, COAMPS-TC,
AND NAVGEM MAKING UP THE EASTERN EDGE OF THE ENVELOPE, WHILE JGSM,
UEM2 AND EEM2 MAKE UP THE WESTERN OUTLIER. BEYOND TAU 48,
CONFIDENCE REMAINS MEDIUM DUE TO THE LARGE SPREAD IN TRACK
GUIDANCE. THE JTWC INTENSITY FORECAST FOLLOWS THE MULTI-MODEL
CONSENSUS THROUGH 36 HOURS DUE TO THE EXPECTED INTENSIFICATION
TREND AND MULTIPLE RAPID INTENSIFICATION (RI) AIDS BEING TRIGGERED.
THE AGGRESSIVE HWRF SOLUTION CALLS FOR TYPHOON INTENSITY IN 12
HOURS BASED ON THE IMPROVING CONVECTIVE STRUCTURE. THE INTENSITY
FORECAST LIES NEAR CONSENSUS THROUGH THE REMAINDER OF THE FORECAST
WITH MEDIUM CONFIDENCE.


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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