WDPN31 PGTW 100900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (CONSON) WARNING NR 
018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.6N 112.0E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 215 NM EAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 8 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) 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 100559Z AMSR2 89GHZ MICROWAVE IMAGE.
INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A PARTIAL 100247Z METOP-C SCATTEROMETER PASS, HEDGED BELOW
DVORAK INTENSITY ESTIMATES FROM RJTD 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: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE POSITIONED TO THE
NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.5 - 55 KTS
   CIMSS SATCON: 49 KTS AT 100152Z
   CIMSS ADT: 49 KTS AT 100550Z

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 AT TAU 48 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 24, 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 BECOME SLIGHTLY MORE
FAVORABLE WITH AN UNEVEN SPREAD TO OVER 130NM BY TAU 72, LENDING
MEDIUM CONFIDENCE TO THE DURATION OF THE JTWC TRACK FORECAST, THAT 
IS LAID CLOSE TO THE MODEL CONSENSUS. THE DETERMINISTIC UK MODEL IS 
THE PRIMARY OUTLIER WHICH SHOWS 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//
NNNN