WDPN31 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.1N 122.7E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 192 NM SOUTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 39 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
14W AS A SWIFTLY INTENSIFYING TYPHOON OVER THE PAST SIX HOURS, SHOWING 
IMPROVING OUTFLOW ALOFT AND BECOMING MUCH MORE STRUCTURALLY SYMMETRIC. 
CIRRUS CLOUD FILAMENTS, OBSERVABLE ON HIMAWARI-9 DERIVED WATER
VAPOR SATELLITE IMAGERY, CONTINUE TO BE PROPELLED OUTWARD ALOFT AND
QUICKLY DRIFT AWAY INTO THE STRONG EQUATORWARD FLOW.  THE SYSTEMS
EYE CONTINUES TO BECOME MORE CIRCULAR IN NATURE (28 X 30 NM) AND
HAS INTERMITTENTLY CLEARED, VIEWABLE ON ANIMATED HIMAWARI-9
VISIBLE SATELLITE IMAGERY. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON 040600Z HIMAWARI-9 VISIBLE AND ENHANCED
INFRARED (EIR) SATELLITE IMAGERY. THE INITIAL INTENSITY OF 115 KTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON MULTI-AGENCY SUBJECTIVE
DVORAK INTENSITY ESTIMATES OF 115KTS, AS WELL AS CIMSS AIDT AND
DPRINT ESTIMATING 116 KTS AND 118KTS, RESPECTIVELY.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
BUILDING TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 126 KTS AT 040450Z
   CIMSS ADT: 122 KTS AT 040530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: AS TY 14W CONTINUES TO TRACK WESTWARD UNDER
THE STEERING INFLUENCE OF THE BUILDING STR TO THE NORTH, SLIGHT
INTENSIFICATION COULD OCCUR FOR A SHORT TIME SPAN (040600Z TO 041200Z) 
UNTIL THE TAIWAN TOPOGRAPHY COMES INTO THE PICTURE. THE CENTRAL 
MOUNTAIN RANGE OF TAIWAN, WITH HIGHEST SUMMIT AT 12,660 FEET, WILL 
LIKELY INFLUENCE THE VERTICAL STRUCTURE FROM 700MB TO THE SURFACE.  
THE AMOUNT OF INFLUENCE THIS TOPOGRAPHICAL FEATURE WILL HAVE ON THE 
STORMS INTENSITY GREATLY DEPENDS ON HOW FAR NORTH OR SOUTH THE SYSTEM 
TRACKS PRIOR TO MAKING LANDFALL ALONG THE EASTERN COAST OF TAIWAN 
BETWEEN TAU 12 AND TAU 24. SHOULD THE SYSTEM TRACK MORE WEST-
SOUTHWESTWARD VICE WESTWARD OR WEST-NORTHWESTWARD, THEN THE SYSTEM 
WILL LIKELY REMAIN STRONGER AND MORE INTENSE. FROM TAU 24 TO TAU 72, 
THE SYSTEM IS FORECAST TO TRACK WESTWARD ACROSS THE TAIWAN STRAIT, 
GRADUALLY LOWERING IN INTENSITY ALONG THE WAY AS COOLER, MORE STABLE 
AIR IS INTRODUCED TO THE SYSTEM FROM THE NORTH.

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN GOOD
AGREEMENT TYPHOON 14W WILL CONTINUE TO TRACK WESTWARD THROUGH TAU
72, SKIRTING THE SOUTHERN REGIONS OF TAIWAN BETWEEN TAU 12 AND TAU
24.  THE TAU 72 CROSS-TRACK SPREAD OF 86NM, AND WITH THE EXCEPTION OF 
THE GFS DETERMINISTIC SOLUTION, ALONG-TRACK SPREAD OF 98NM CONTRIBUTED 
TO A FORECAST CONFIDENCE FOR BOTH TRACK AND INTENSITY OF MEDIUM. AFTER 
TAU 72, THE TRIFURCATION MENTIONED IN THE WARNING 019
PROGNOSTIC REASONING STILL EXISTS, BUT MOST GUIDANCE FAVORS A 
SOUTHWESTWARD TRACK AFTER TAU 72. THE GFS DETERMINISTIC SOLUTION 
TRACKS THE SYSTEM NORTHWESTWARD THROUGH TAU 120 FROM TAU 72, WHILE THE 
JGSM SOLUTION CHECKMARKS THE SYSTEM ONTO A RECIPROCAL HEADING NEAR TAU 
96 AND MAINTAINS THROUGH TAU 120. WITH THESE TWO EXCEPTIONS, THE BULK 
OF NUMERICAL GUIDANCE SUGGESTS TY 14W WILL SKIRT THE SOUTH CHINA COAST 
NEAR TAU 72 AND THEN TAKE A SOUTHWESTWARD TRACK THROUGH TAU 120. AFTER 
TAU 72, THE TRACK FORECAST CONFIDENCE IS HELD AT MEDIUM FOR THIS 
REASON.

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