WDPN31 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (CONSON) WARNING NR 
017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.8N 112.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 248 NM EAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS
MAINTAINED OVERALL CONVECTIVE SIGNATURE WITH THE MAIN FEEDER BAND
WRAPPING IN FROM THE NORTH AND INTO THE DEEP CENTRAL CONVECTION
THAT IS OBSCURING THE LOW LEVEL CIRCULATION (LLC). THE INITIAL 
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A RAGGED BUT 
DEFINED LLC IN THE 092327Z SSMIS 89GHZ MICROWAVE IMAGE. THE INITIAL 
INTENSITY IS ALSO PLACED WITH MEDIUM CONFIDENCE BASED ON THE MEDIAN 
OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SUSTAINED 
CONVECTIVE SIGNATURE. THE ENVIRONMENT IS MARGINALLY FAVORABLE WITH 
LOW VWS AND WARM SSTS OFFSET BY WEAK RADIAL OUTFLOW. THE CYCLONE IS 
TRACKING ALONG THE SOUTHERN PERIPHERY OF THE STR TO THE NORTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 45 KTS AT 092350Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK RADIAL

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: TS CONSON WILL GENERALLY TRACK WESTWARD UNDER
THE STR TOWARD CENTRAL VIETNAM AND MAKE LANDFALL JUST BEFORE TAU 72
NEAR DANANG. AFTERWARD, IT WILL TURN MORE WEST-NORTHWESTWARD AS THE
STR IS WEAKENED BY A MIDLATITUDE TROUGH. THE MARGINALLY FAVORABLE
ENVIRONMENT WILL FUEL A SLOW INTENSIFICATION TO A PEAK OF 65KTS BY
TAU 24; AFTERWARD, INCREASING VWS WILL GRADUALLY WEAKEN IT DOWN TO
35KTS BY LANDFALL. CONCURRENTLY, INTERACTION WITH THE SOUTHWESTERLY
MONSOON IN THE GULF OF TONKIN WILL MAINTAIN THE WESTWARD TRACK,
EFFECTIVELY DELAYING THE WEST-NORTHWESTWARD TRACK UNTIL AFTER
LANDFALL. TS 18W WILL DISSIPATE DUE TO FRICTIONAL EFFECTS OVER LAND
BY TAU 96.

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN POOR AGREEMENT WITH AN
UNEVEN SPREAD TO OVER 200NM BY TAU 96, LENDING MEDIUM CONFIDENCE TO
THE WHOLE DURATION OF THE JTWC TRACK FORECAST THAT IS LAID CLOSE TO
THE MODEL CONSENSUS. THERE IS ALSO MEDIUM CONFIDENCE IN THE JTWC
INTENSITY FORECAST UP TO TAU 72, THEN LOW CONFIDENCE AFTERWARD DUE
TO THE VARIABILITY INTRODUCED BY LAND INTERACTION.

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