WDPN31 PGTW 101500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (CONSON) WARNING NR 
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.6N 111.4E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 181 NM EAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION SITUATED TO THE WEST OF THE PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON THE 101041Z AMSR2 89GHZ MICROWAVE IMAGE
WITH A SMALL CONSOLIDATED PATCH OF CONVECTION NEAR THE LLCC.
INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON SCATTEROMETRY BUT, HEDGED BELOW DVORAK INTENSITY ESTIMATES
FROM ADT AND PGTW. DESPITE WARM SEA SURFACE TEMPERATURES, THE WEAK
EQUATORWARD OUTFLOW AND HIGH VERTICAL WIND SHEAR MAINTAIN AN ONLY
MARGINALLY FAVORABLE ENVIRONMENT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 49 KTS AT 101140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TS CONSON WILL CONTINUE TO TRACK GENERALLY
WESTWARD UNDER THE STR UNTIL LANDFALL SHORTLY AFTER TAU 36 WHILE
PASSING THROUGH WARM (29-30 DEGREE CELSIUS) SEA SURFACE
TEMPERATURES UNDER A WEAK EQUATORWARD OUTFLOW CHANNEL. AFTERWARD,
IT WILL TURN MORE WEST-NORTHWESTWARD AS THE STR IS WEAKENED BY A
MIDLATITUDE TROUGH. THE MARGINALLY FAVORABLE ENVIRONMENT MAY FUEL A
SLIGHT INTENSIFICATION TO A PEAK OF 45 KNOTS BY TAU 12, HOWEVER,
SUSTAINED VWS WILL LIKELY HAMPER SIGNIFICANT DEVELOPMENT BEFORE
LANDFALL. TS 18W IS EXPECTED TO DISSIPATE DUE TO FRICTIONAL EFFECTS
OVER LAND BY TAU 72.

MODEL DISCUSSION: NUMERICAL MODELS HAVE MAINTAINED WITH AN UNEVEN
SPREAD TO OVER 130NM BY TAU 48, LENDING MEDIUM CONFIDENCE TO THE
DURATION OF THE JTWC TRACK FORECAST, THAT IS LAID CLOSE TO THE
MODEL CONSENSUS. THE DETERMINISTIC UK MODEL AND NAVGEM ARE THE
PRIMARY OUTLIERS, WHICH SHOW A MORE SOUTHWESTERLY TRACK. THERE IS
MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST DUE TO ITS CURRENT
COMPETING ENVIRONMENT AND THE VARIABILITY INTRODUCED BY LAND
INTERACTION.

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