WDPN31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 034//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.4N 114.9E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 67 NM SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AS INDICATED IN RECENT ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY, TYPHOON (TY) 14W HAD MAINTAINED A PINHOLE EYE UNTIL ABOUT
071700Z. A 071018Z RCM-3 IMAGE DEPICTED A COMPACT SYSTEM WITH A
RADIUS OF MAXIMUM WINDS OF 8 NM AND A MAXIMUM INTENSITY OF 107 KTS,
WHICH WAS HIGHER THAN MANY OF THE SUBJECTIVE AND OBJECTIVE INTENSITY 
ESTIMATES AS IS TYPICAL WITH THIS TYPE OF SMALL SYSTEM. TO FURTHER 
COMPLICATE THE SITUATION, RADAR IMAGERY DEPICTS CONCENTRIC EYEWALLS, 
WITH A VERY SMALL INNER EYEWALL BOUNCING AROUND INSIDE THE OUTER 
EYEWALL AND A CLEARLY DEFINED MOAT BETWEEN THE TWO EYEWALLS. THE 
CIMSS M-PERC PRODUCT INDICATES AN EYEWALL REPLACEMENT CYCLE (ERC) 
WITH TWO DISTINCT WEAK PEAKS IN ERC ONSET PROBABILITIES TO ABOUT 30 
TO 35 PERCENT. THE SYSTEM DOES APPEAR TO BE WEAKENING NOW WITH A 
CLOUD-FILLED EYE EVIDENT IN EIR. SUBJECTIVE AND OBJECTIVE DVORAK 
INTENSITY ESTIMATES HAVE DECREASED, ALTHOUGH LIKELY TOO LOW, 
THEREFORE THE INITIAL INTENSITY IS ASSESSED AT 95 KNOTS JUST ABOVE 
THE RJTD CURRENT INTENSITY ESTIMATE OF 5.0 (90 KNOTS) BUT ALIGNED 
WITH THE RECENT RCM-3 SAR DATA.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING INFLUENCE WITH A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND A
WEAK STR POSITIONED TO THE WEST.  

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 76 KTS AT 071735Z
   CIMSS ADT: 74 KTS AT 071730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: MINOR INTERACTION WITH LAND

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 14W IS FORECAST TO TRACK SLOWLY THROUGH TAU
24 WITHIN THE COMPETING STEERING ENVIRONMENT WITH GRADUAL WEAKENING
AS THE INNER EYEWALL ERODES AND THE ERC COMPLETES. RECENT RADAR
IMAGERY AFTER 071800Z INDICATES THAT THE SMALL INNER EYEWALL IS
DETERIORATING. AFTER TAU 24, A WEAK EXTENSION OF THE LOW- TO
MID-LEVEL STR IS FORECAST TO BUILD TO THE NORTH, WHICH WILL
ACCELERATE THE SYSTEM WEST-SOUTHWESTWARD THROUGH THE FORECAST
PERIOD. AS THE SYSTEM SKIRTS THE SOUTHEAST COAST OF CHINA AND
TRACKS OVER HAINAN ISLAND, SIGNIFICANT WEAKENING WILL OCCUR WITH
EVENTUAL DISSIPATION NEAR TAU 120 AS TY 14W TRACKS INTO VIETNAM AND
LAOS.       

MODEL DISCUSSION: WITH THE EXCEPTION OF THE UK-MET ENSEMBLE MEAN 
(UEMN) AND THE GALWEM TRACKER (AFUM), DETERMINISTIC GUIDANCE REMAINS 
IN FAIR AGREEMENT LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK 
FORECAST THROUGH TAU 120. THE 071200Z GFS AND ECMWF ENSEMBLES (GEFS 
AND EPS) ARE ALSO IN FAIR AGREEMENT AND SHOW RAPID WEAKENING AFTER 
TAU 24. 

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