WDPN32 PGTW 092100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (MUIFA) 
WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 126.8E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 388 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT THE
OVERALL STRUCTURE CONTINUES TO IMPROVE AND CONSOLIDATE WITH
RADIALLY EXPANDING CENTRAL CONVECTION THAT IS OBSCURING THE LOW
LEVEL CIRCULATION CENTER (LLCC). AN EARLIER 091005Z SSMIS 37GHZ
MICROWAVE IMAGE REVEALED A WEAK MICROWAVE EYE FEATURE, WHILE THE
91GHZ MICROWAVE IMAGE REVEALS AN OVERALL IMPROVED CONVECTIVE
STRUCTURE, WITH CURVED DEEP CONVECTION FOCUSED AROUND THE NORTHERN
PERIPHERY OF 14W. ADDITIONALLY, AN EARLIER 091232Z METOP-B ASCAT 
IMAGE INDICATES A SYMMETRIC WELL DEFINED WIND FIELD, AND EXTRAPOLATION 
OF THIS FEATURE ALONG WITH DVORAK AGENCY POSITION FIXES PROVIDES HIGH
CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY OF 65 KTS
IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE IMPROVED CONVECTIVE
STRUCTURE AS WELL AS A BLEND OF AGENCY DVORAK CURRENT INTENSITY
ESTIMATES WITH PGTW SPECIFICALLY INDICATING T4.0.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WEST PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON 14W HAS TRACKED GENERALLY
NORTHWESTWARD OVER THE PAST 12 HOURS ALONG THE WESTERN PERIPHERY OF
AN ELONGATED MID-LEVEL SUBTROPICAL RIDGE TO THE EAST. OVERALL, THE
CURRENT ENVIRONMENT IS FAVORABLE BASED ON ANIMATED WATER VAPOR
IMAGERY WHICH SHOWS AN ELONGATED TROPICAL UPPER TROPOSPHERIC TROUGH
(TUTT) NOW POSITIONED TO THE NORTHWEST OF THE LLCC, IMPARTING
INCREASED POLEWARD OUTFLOW, ALLOWING FOR BETTER CONSOLIDATION AND
THUS A MORE SYMMETRICAL EXPANDED CONVECTIVE STRUCTURE. OVER THE
NEXT 24 HOURS, THE GENERAL MOTION OF 14W IS FORECAST TO CONTINUE
NORTHWESTWARD AS THE SUBTROPICAL RIDGE (STR) BUILDS SOUTH OF HONSHU
AND REORIENTS IN A MORE SOUTHEAST TO NORTHWEST AXIS, AT THE SAME
TIME THE SYSTEM WILL CONTINUE TO INTENSIFY. BY TAU 48, THE STEERING
PATTERN CHANGES SIGNIFICANTLY, WITH A NEAR-EQUATORIAL RIDGE (NER)
DEVELOPING TO THE SOUTH, WITH ANOTHER STR DEVELOPING OVER SOUTHERN
CHINA AND A TROUGH TO THE NORTHWEST. AS THESE SYNOPTIC FEATURES SET
IN PLACE, IT WILL RESULT IN CONSIDERABLY SLOWER TRACK SPEED THROUGH
TAU 72 AND ALLOW 14W TO BECOME QUASI-STATIONARY BEFORE THEN
DRIFTING SLOWLY NORTH-NORTHWESTWARD. THE SYSTEM WILL ALSO MOVE OVER
THE RELATIVELY COOL, VERY LOW OHC POOL LEFT IN THE WAKE OF STY 12W,
AND REMAIN OVER THIS COOL POOL WHICH WILL WEAKEN THE SYSTEM. BY TAU 
96, 14W WILL BEGIN TO BE INFLUENCED BY A MID LATITUDE SHORTWAVE 
TROUGH TO THE NORTH, WHICH WILL ALLOW A WEAKNESS IN THE STEERING 
RIDGE, ULTIMATELY ALLOWING THE SYSTEM TO TRANSIT IN A FASTER TRACK 
SPEED NORTHWARD. AS THE SYSTEM CONTINUES INTO THE EAST CHINA SEA, IT 
WILL HAVE LOST A SIGNIFICANT AMOUNT OF INTENSITY DUE TO THE
AFOREMENTIONED IMPACT FROM THE QUASI-STATIONARY MOTION OVER LOW
OHC, BUT WILL LIKELY STILL MAINTAIN TYPHOON STRENGTH.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT THROUGH
TAU 48 WITH ONLY A 90NM SPREAD IN THE SOLUTIONS. HOWEVER, AS
EXPLAINED IN THE FORECAST DISCUSSION, THE STEERING DYNAMICS BECOME
MORE COMPLEX RESULTING IN NUMERICAL MODEL GUIDANCE SPREAD OF 200NM
AFTER TAU 72 INCREASING BY THE END OF THE FORECAST. SPECIFICALLY,
COAMPS-TC (GFS VERSION) REPRESENTS THE WESTERN OUTLIER, WHERE AS
THE NAVGEM IS THE EASTERN OUTLIER. THEREFORE, THE JTWC FORECAST IS
PLACED WITH HIGH CONFIDENCE THROUGH TAU 48, HOWEVER THE EXTENDED
TRACK FORECAST IS PLACED WITH LOWER CONFIDENCE. RELIABLE INTENSITY
GUIDANCE IS IN GOOD AGREEMENT OF ALL MEMBERS WITH THE EXCEPTION OF
COAMPS-TC (GFS VERSION) SHOWING RAPID INTENSIFICATION (RI) THROUGH
TAU 48. AFTER WHICH, ALL INTENSITY GUIDANCE AFTER TAU 72 SHOWS A
DECREASE IN INTENSITY THROUGH OUT THE REMAINDER OF THE FORECAST.
THE MAIN CONTRIBUTING FACTOR TO THIS DECREASE IN INTENSITY WILL BE
THE DURATION THE SYSTEM IS QUASI-STATIONARY EAST OF TAIWAN. FOR THESE 
REASONS THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE.    

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