WDPN33 PGTW 022100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (KRATHON) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.2N 119.7E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 39 NM SOUTHWEST OF KAOHSIUNG, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
REMAINS SYMMETRICAL; HOWEVER, STRIATIONS AND WARMING CLOUD TOPS
ALONG THE NORTHERN SECTORS HAVE BECOME PROMINENT AS THAT AREA OF
THE CYCLONE HAS BECOME EXPOSED TO INCREASING VWS AS TY KRATHON
CLOSED IN ON TAIWAN. THE 10-NM EYE HAS BECOME MORE RAGGED BUT STILL
WELL-DEFINED. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON A DEFINED LLCC FEATURE IN A COMPOSITE RADAR LOOP THAT
LINED UP WELL WITH THE EYE, ADJUSTED FOR A SLIGHT FORWARD TILT. THE
INITIAL INTENSITY OF 90KTS IS ALSO PLACED WITH HIGH CONFIDENCE
BASED ON CLOSELY-VALUED AGENCY AND AUTOMATED DVORAK ESTIMATES THAT
CAPTURE THE WEAKENING TREND AND REFLECTS THE 6-HR CONVECTIVE
DETERIORATION EVIDENT ON THE EIR ANIMATION.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 98 KTS AT 021437Z
   CIMSS ADT: 90 KTS AT 021730Z
   CIMSS DPRNT: 90 KTS AT 021730Z
   CIMSS DMNT: 88 KTS AT 02103Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 20W WILL TRACK GENERALLY NORTH-NORTHEASTWARD 
UNDER THE STEERING INFLUENCE OF THE STR TO THE EAST, MAKE LANDFALL 
NEAR KAOHSIUNG JUST BEFORE TAU 12, AND THEN TRACK INTO CENTRAL TAIWAN. 
AFTER TAU 36, A NORTHEASTWARD EXTENSION OF THE STR TO THE WEST WILL 
BUILD AND ASSUME STEERING, DRIVING THE SYSTEM WESTWARD INTO THE TAIWAN 
STRAIT THEN SOUTHWESTWARD TOWARD THE SOUTH CHINA SEA. THE UNFAVORABLE 
ENVIRONMENT WILL GET WORSE WITH INCREASING VWS AND LAND INTERACTION 
WITH THE EXCEPTIONALLY RAGGED TERRAIN OF TAIWAN, RAPIDLY ERODING THE 
SYSTEM DOWN TO 40KTS BY TAU 36. BY TAU 48, AS THE SYSTEM EXITS BACK 
OVER WATER IN THE TAIWAN STRAIT, COOLER SST AND INTRUSION OF COOL DRY 
AIR IN ADDITION TO THE HIGH VWS, WILL DISSIPATE THE SYSTEM BY TAU 72 
AS IT MEANDERS TOWARD THE SOUTH CHINA SEA. 

MODEL DISCUSSION: NUMERICAL MODELS ARE NOT IN GOOD AGREEMENT WITH
JUST A SLIGHT MAJORITY SUPPORTING THE JTWC FORECAST TRACK.
SIGNIFICANT OUTLIERS INCLUDE AFUM THAT SHOOTS THE VORTEX
SOUTHEASTWARD, UEMN GOING FOR A NORTHEASTWARD TRAJECTORY TOWARD
JAPAN, AND NVGM ON A MORE WESTWARD TRACK TOWARD CENTRAL CHINA. IN
VIEW OF THESE, THERE IS LOW CONFIDENCE IN THE JTWC TRACK AND
INTENSITY FORECASTS.  

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