WDPN32 PGTW 220300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 24W (RAGASA) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.3N 122.9E
   INITIAL INTENSITY: 145 KTS
   GEOGRAPHIC REFERENCE: 520 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
THE CIMSS M-PERC PRODUCT NOW INDICATES THE EYEWALL REPLACEMENT CYCLE 
(ERC) PREVIOUSLY INDICATED HAS ENDED WITH NO SIGNIFICANT CHANGE IN 
THE INTENSITY. ANIMATED INFRARED (EIR) SATELLITE IMAGERY INDICATES 
SLIGHT WEAKENING OF THE CORE CONVECTION, WITH COOLING CLOUD TOP 
TEMPERATURES AND A MORE ASYMMETRIC APPEARANCE. HOWEVER, SUPER TYPHOON 
(STY) 24W HAS MAINTAINED A SYMMETRIC 40NM DIAMETER EYE WHILE TRACKING 
STEADILY WESTWARD. A 212149Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE 
IMAGE REVEALS SPIRAL BANDING WRAPPING INTO A COMPACT CORE, WITH A 
WELL-DEFINED MICROWAVE EYE FEATURE. ENVIRONMENTAL CONDITIONS REMAIN 
HIGHLY FAVORABLE, WITH STRONG RADIAL OUTFLOW AND LOW VERTICAL WIND 
SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
THE EYE FEATURE IN EIR SATELLITE IMAGERY. THE INITIAL INTENSITY OF 
145 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY CURRENT 
INTENSITY ESTIMATES RANGING FROM 7.0-7.5 (140-155 KNOTS) AND THE 
CIMSS OBJECTIVE ESTIMATES RANGING FROM 137 TO 153 KNOTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.5 - 155 KTS
   RJTD: T7.0 - 140 KTS 
   RCTP: T7.5 - 155 KTS
   KNES: T7.0 - 140 KTS 
   DEMS: T7.5 - 155 KTS
   CIMSS SATCON: 153 KTS AT 220030Z
   CIMSS ADT: 137 KTS AT 220010Z
   CIMSS AIDT: 143 KTS AT 220010Z
   CIMSS D-MINT: 152 KTS AT 212213Z
   CIMSS D-PRINT: 142 KTS AT 220030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: STY 24W WILL TRACK WESTWARD THROUGH THE
FORECAST PERIOD ALONG THE SOUTHERN PERIPHERY OF THE STR. HOWEVER, A
MIDLATITUDE SHORTWAVE TROUGH EMBEDDED WITHIN ZONAL WESTERLIES IS
FORECAST TO BRIEFLY WEAKEN THE STR AFTER TAU 48, WHICH MAY PRODUCE
A SHORT-TERM WEST-NORTHWESTWARD TRACK MOTION AS THE SYSTEM TRACKS
NEAR THE LEIZHOU PENINSULA. AFTER THIS TROUGH PROPAGATES EASTWARD,
THE STR WILL QUICKLY REBUILD OVER CHINA DRIVING THE SYSTEM INTO
NORTHERN VIETNAM. STY 24W WILL MAINTAIN STY INTENSITY THROUGH TAU
24, WITH STEADY WEAKENING AFTER TAU 36 DUE TO UPWELLING COOLER
WATER AND FRICTIONAL EFFECTS. AFTER TAU 48, THE SYSTEM WILL WEAKEN
MORE RAPIDLY AS IT SKIRTS THE SOUTHERN COAST OF CHINA. AFTER
LANDFALL NEAR TAU 84 OVER VIETNAM, THE SYSTEM WILL RAPIDLY WEAKEN
AS IT TRACKS INLAND.       

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, NUMERICAL MODEL
GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD,
WITH AN 95-100NM CROSS-TRACK SPREAD FROM TAU 72 TO TAU 96. THE
211800Z GEFS AND EPS ENSEMBLES SUPPORTS THE JTWC FORECAST TRACK
WITH MEDIUM CONFIDENCE AND INDICATE A HIGH PROBABILITY OF THE TRACK
PASSING NORTH OF HAINAN ISLAND. RELIABLE INETNSITY GUIDANCE
SUPPORTS THE JTWC INTENSITY FORECAST WITH MEDIUM CONFIDENCE.  

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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