WDPN32 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (CHABA) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.6N 111.6E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 177 NM SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND ANIMATED RADAR
DATA DEPICT PERSISTENT DEEP CONVECTION WRAPPING AROUND A WELL-
DEFINED 
LOW-LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS PLACED WITH 
MEDIUM CONFIDENCE BASED ON RECENT SATELLITE POSITION FIXES FROM 
MULTIPLE REPORTING AGENCIES AND THE ANIMATED RADAR IMAGERY. THE 
INITIAL INTENSITY OF 75 KTS IS ASSESSED WITH MEDIUM CONFIDENCE 
BETWEEN AUTOMATED DVORAK ESTIMATES AT 87 KNOTS ON THE HIGH END AND 
SUBJECTIVE DVORAK EQUIVALENT VALUES OF 65 KNOTS ON THE LOW END. THE 
CIRCULATION AND ASSOCIATED CONVECTIVE BANDING HAVE BECOME NOTICEABLY 
MORE COMPACT,
SUPPORTING THE ESTIMATED 10 KNOT INTENSIFICATION OVER THE PAST SIX
HOURS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF MID TO
UPPER-LEVEL
SUBTROPICAL RIDGING TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 87 KTS AT 012340Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 04W IS EXPECTED TO MAKE JUST TO THE EAST OF
ZHANJIANG, CHINA WITHIN THE NEXT SIX TO TWELVE HOURS UNDER THE
CONTINUED STEERING INFLUENCE OF THE MID TO UPPER-LEVEL SUBTROPICAL
RIDGING TO THE EAST. THE SYSTEM WILL CONTINUE INLAND AND DISSIPATE
RAPIDLY THEREAFTER, WITH FULL DISSIPATION ANTICIPATED BY TAU 48.
ADDITIONAL INTENSIFICATION IS POSSIBLE PRIOR TO LANDFALL AS THE
SYSTEM PASSES OVER VERY WARM WATER WITH FAVORABLY LOW VERTICAL WIND
SHEAR AND SUPPORTIVE DIFFLUENCE ALOFT. HOWEVER, ANY
INTENSIFICATION IS EXPECTED TO BE MINIMAL AS LAND INTERACTION IS
ALREADY STARTING TO OCCUR.

MODEL DISCUSSION: MODEL TRACK AND INTENSITY FORECAST GUIDANCE, BOTH
DETERMINISTIC AND ENSEMBLE-BASED, ARE IN GOOD AGREEMENT, LENDING
HIGH CONFIDENCE TO THE CURRENT FORECAST. THE TRACK FORECAST IS
SITUATED NEAR BOTH THE CURRENT MULTI-MODEL CONSENSUS AND THE
PREVIOUS JTWC OFFICIAL FORECAST.

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