WDPN31 PGTW 040300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.1N 123.6E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 214 NM SOUTH-SOUTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 14W HAS CONSOLIDATED QUICKLY OVER THE PAST SIX HOURS
WITH A RAPIDLY MOISTENING CORE AND NO EVIDENCE OF THE DRY AIR
ENTRAINMENT THAT WAS PRESENT EARLIER OVER THE NORTHEAST QUADRANT. IN 
ADDITION TO THE ROBUST EQUATORWARD OUTFLOW CHANNEL, ANIMATED WATER 
VAPOR IMAGERY SHOWS STRONG RADIAL OUTFLOW WITH A SUDDEN BURST OR 
EXPANSION OF POLEWARD OUTFLOW. THIS HAS OBVIOUSLY LED TO SIGNIFICANT 
IMPROVEMENTS IN THE CONVECTIVE STRUCTURE AS INDICATED IN ANIMATED 
ENHANCED INFRARED (EIR) SATELLITE IMAGERY, WHICH NOW DEPICTS A 20 TO 
25 NM EYE WITH IMPROVED EYEWALL STRUCTURE. CONSEQUENTLY, DVORAK 
ESTIMATES HAVE JUMPED TO 102 KNOTS FROM ALL AGENCIES. THE LATEST 
IMAGERY (AFTER 040000Z) WOULD LIKELY YIELD A T6.0 (115 KNOTS). CIMSS 
OBJECTIVE INTENSITY ESTIMATES (ADT, AIDT) HAVE ALSO INCREASED AND 
RANGE FROM 109 TO 112 KNOTS. THE INITIAL INTENSITY IS ASSESSED AT 100 
KNOTS (WITH MEDIUM CONFIDENCE) BASED ON THE DVORAK ESTIMATES AT 
040000Z BUT CLEARLY COULD NOW BE IN THE 110 TO 115 KNOT RANGE. THE 
SYSTEM IS ACCELERATING TOWARD TAIWAN SO HAS A BRIEF WINDOW OF 
OPPORTUNITY BEFORE WEAKENING WILL COMMENCE. THE INITIAL POSITION AND 
RECENT TRACK MOTION IS BASED ON RADAR IMAGERY AND RADAR FIXES WITH 
HIGH CONFIDENCE.          

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 112 KTS AT 040000Z
   CIMSS AIDT: 109 KTS AT 040000Z

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

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: TY 14W IS TRACKING GENERALLY WESTWARD AND IS 
FORECAST TO MAKE LANDFALL OVER SOUTHERN TAIWAN JUST AFTER TAU 24. AS 
IT APPROACHES AND CROSSES SOUTHERN TAIWAN, TY 14W WILL WEAKEN 
SIGNIFICANTLY HINDERED SOMEWHAT BY MODERATE TO HIGH VERTICAL WIND 
SHEAR (VWS) OFFSET BY STRONG OUTFLOW. AFTER TAU 36, THE SYSTEM WILL 
CONTINUE TRACKING SLOWLY WESTWARD THEN WEST-SOUTHWESTWARD TOWARD HONG 
KONG WITH FURTHER WEAKENING DUE TO INTERACTION WITH THE COOLER, MORE 
STABLE NORTHEAST SURGE FLOW ENTRAINING INTO THE WESTERN SEMICIRCLE 
AND EVENTUALLY FRICTIONAL EFFECTS ALONG THE SOUTHEAST COAST OF CHINA. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT 
THROUGH ONLY TAU 36 WITH A 75 NM CROSS-TRACK SPREAD IN THE CONSENSUS 
VORTEX TRACKERS. AFTER TAU 36, GUIDANCE DIVERGES QUICKLY WITH A LARGE 
SPREAD AND LOW CONFIDENCE. THERE IS BASICALLY A TRIFURCATION WITH 
GROUP ONE (NVGM, AEMN AND EEMN) INDICATING A SOUTHWESTWARD TRACK, 
GROUP 2 (EGRR, ECMF) STALLING THE SYSTEM NORTHEAST OF HONG KONG, AND 
GROUP THREE (JGSM, AVNO AND UEMN) TRACKING THE SYSTEM POLEWARD. 
PROBABILISTIC GUIDANCE FROM THE ECMWF ENSEMBLE (031200Z RUN) SHOWS A 
GRADUAL SOUTHWESTWARD TURN WHILE THE GFS ENSEMBLE (031800Z RUN) IS 
ALL OVER THE PLACE. IF TY 14W TRACKS SOUTH OF TAIWAN AS INDICATED BY
THE MESOSCALE MODELS (COAMPS-TC AND HAFS-A), THERE IS SOME POTENTIAL
FOR THE SYSTEM TO MAINTAIN TYPHOON INTENSITY FOR A LONGER DURATION
AS IT MAY AVOID ANY DELETERIOUS EFFECTS FROM THE NORTHEAST SURGE
FLOW.    

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