WDPN32 PGTW 031500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (ETAU) WARNING/
NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 031200Z6 TO 081200Z1 AUG 2003.
   A. TROPICAL STORM (TS) 11W (ETAU), LOCATED APPROXIMATELY 350 NM
WEST OF GUAM, HAS TRACKED NORTHWESTWARD OVER THE PAST 6 HOURS.
THE WARNING POSITION IS BASED ON 031130Z8 ENHANCED INFRARED
SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE
CURRENT INTENSITY ESTIMATES OF 45 KNOTS. TS 11W CONTINUES TO
INTENSIFY AS IT ENJOYS GOOD EQUATORWARD FLOW. A RECENT 031027Z3
SSMI PASS SHOWS DEEP CONVECTION OCCURRING IN THE SOUTHERN QUADRANT
WITH A .6 SPIRAL WRAP.
   B. TS 11W CONTINUES TO TRACK NORTHWESTWARDS AROUND THE SOUTH-
WEST QUADRANT OF A LOW TO MID LEVEL STEERING RIDGE TO THE NORTH-
EAST. TS 11W WILL TRANSITION TO A MORE POLEWARD TRACK AS THE RIDGE
BUILDS. AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, NCEP (GFS),
EGRR AND JTYM ARE IN GOOD AGREEMENT WITH THIS SCENARIO. EGGR IS A
SIGNIFICANT OUTLIER TO THIS SCENARIO. IT NEVER INTENSIFIES TS 11W
ENOUGH TO ALLOW IT TO BECOME INFLUENCED BY THE STEERING RIDGE TO
THE NORTHEAST AND FORECASTS 11W TO TRACK WESTWARD. THIS FORECAST
IS BASED ON PERSISTENCE AND A BLEND OF THE AVAILABLE DYNAMIC MODELS
WITH LESS EMPHASIS ON EGRR.
   C. TS 11W WILL INITIALLY CONTINUE TO ENJOY GOOD EQUATORWARD 
OUTFLOW AND IS FORECAST TO TRANSIT A REGION OF WEAK VERTICAL SHEAR
FOR THE ENTIRE FORECAST PERIOD. THIS SCENARIO SUPPORTS TS 11W
INTENSIFYING AT A CLIMATOLOGICAL RATE OF ONE DVORAK PER DAY. 
   D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN 
AVERAGE SIZED SYSTEM.
   E. THE EXTENDED FORECAST WILL SEE TS 11W LINKING UP WITH A
MID-LATITUDE TROUGH TRANSITING THROUGH JAPAN AND ALLOW TS 11W TO 
RECURVE AND ACCELERATE NORTHEASTWARDS AND BEGIN UNDERGOING EXTRA-
TROPICAL TRANSITION AS IT ENTERS THE BAROCLINIC ZONE. 
FORECAST TEAM: GRUBER/RONSSE/EDBERG//
BT
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