WDPN31 PGTW 040300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W (EIGHT) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.5N 115.1E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 51 NM EAST-NORTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 8 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CONSOLIDATING LOW-LEVEL CIRCULATION (LLC) WITH IMPROVED CONVECTIVE
BANDING OVER THE SOUTHERN SEMICIRCLE OVER WARM SST (29-30C) AND
FLARING CONVECTION OVERLAND. ANIMATED RADAR IMAGERY FROM THE HONG
KONG RADAR CLEARLY SHOWED IMPROVING CONVECTIVE STRUCTURE AS THE
SYSTEM APPROACHED AND SKIRTED THE SOUTHERN COAST OF CHINA. RECENT
RADAR IMAGERY SHOWS A DEFINED CENTER MAKING LANDFALL NORTHEAST OF
HONG KONG NEAR DANSHUI ON A WEST-NORTHWESTWARD TRAJECTORY. BASED ON 
THE RADAR IMAGERY, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION. 
SURFACE OBSERVATIONS ARE SPARSE IN THE LANDFALL REGION, HOWEVER, 
SHANWEI (59501) REPORTED A SIGNIFICANT 24-HOUR DECREASE IN SLP FROM 
1007MB TO 1003MB, AND A 032000Z SHIP OBSERVATION IN THE EASTERN 
PERIPHERY (22.4N 116.2E) OF THE SYSTEM (31NM ENE FROM THE 032000Z 
POSITION) REPORTED SOUTHEASTERLY WINDS AT 30 KNOTS. UPPER-LEVEL 
CONDITIONS ARE MARGINALLY-FAVORABLE WITH MODERATE EQUATORWARD 
OUTFLOW, WEAK POLEWARD OUTFLOW AND LOW TO MODERATE (15-20 KNOTS) 
VERTICAL WIND SHEAR. INTERACTION WITH LAND IS THE PRIMARY HINDRANCE. 
THE INITIAL INTENSITY OF 25 KTS IS ASSESSED WITH HIGH CONFIDENCE 
BASED ON THE PGTW DVORAK ESTIMATE.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: INTERACTION WITH LAND

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 08W IS FORECAST TO CONTINUE TRACKING INLAND
THROUGH THE FORECAST PERIOD WITH DISSIPATION EXPECTED BY TAU 24 DUE
TO INTERACTION WITH LAND. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT
WITH ALL MODELS INDICATING A WEST-NORTHWESTWARD TO NORTHWESTWARD
TRACK THUS THERE IS MEDIUM CONFIDENCE IN THE JTWC FORECAST TRACK.
ENSEMBLE GUIDANCE SHOWS A SIMILAR TRACK WITH NO SOLUTIONS TRACKING
THE SYSTEM BACK OVER WATER. INTENSITY GUIDANCE IS LIMITED BUT
INDICATES A 20-30 KNOT INTENSITY AT TAU 12 THEN STEADY WEAKENING
THROUGH TAU 24.

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