WDPN31 PGTW 191500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W (LINFA)
WARNING NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL STORM (TS) 03W (LINFA) HAS SLOWLY INCREASED ITS 
INTENSITY TO 50 KNOTS OVER THE LAST 12 HOURS. INTENSITY IS BASED ON 
DVORAK ESTIMATES FROM PGTW AND KNES ALONG WITH A 190609Z TRMM IMAGE 
SHOWING A MICROWAVE EYE-LIKE FEATURE. ANIMATED WATER VAPOR IMAGERY 
CONTINUES TO SHOW GOOD EQUATORWARD OUTFLOW. POLEWARD OUTFLOW 
CONTINUES TO BE HAMPERED BY MID-LEVEL ANTICYCLONE TO THE NORTH. TS 
03W HAS ACCELERATED TOWARDS THE NORTH AS THE LOW- TO MID-LEVEL 
SUBTROPICAL RIDGE (STR) TO THE EAST HAS STRENGTHENED AND A MID-LEVEL 
RIDGE TO THE NORTH HAS ERODED. 
3. FORECAST REASONING
    A. FORECAST PHILOSOPHY HAS CHANGED SINCE THE PREVIOUS PROGNOSTIC 
REASONING. FASTER THAN EXPECTED ERODING OF THE MID-LEVEL ANTICYCLONE 
OVER SOUTHERN CHINA HAS CAUSED THE SYSTEM TO TRACK MORE NORTHWARD 
THAN PREVIOUSLY PREDICTED. 
    B. TS 03W WILL CONTINUE TO TRACK SLOWLY OVER THE NEXT 24
TO 36 HOURS IN AN AREA OF COMPETING STEERING INFLUENCES. THE 
COMPETING STEERING ENVIRONMENT IS COMPRISED OF A MID-LEVEL 
ANTICYCLONE OVER SOUTHERN CHINA TO THE NORTH AND THE LOW- TO MID-
LEVEL SUBTROPICAL RIDGE TO THE EAST. AS THE ANTICYCLONE OVER CHINA 
CONTINUES TO WEAKEN THROUGH TAU 36, TS 03W WILL SLOWLY ACCELERATE 
AND TRACK NORTH-NORTHEASTERLY UNTIL COMING UNDER THE INFLUENCE OF 
STRONG WESTERLY FLOW NEAR THE MID-LATITUDES. BETWEEN TAU 36-48, THE
SYSTEM IS EXPECTED TO TURN MORE EASTERLY AND TRACK ALONG A WEAK 
BOUNDARY THAT EXTENDS FROM NORTHERN TAIWAN EASTWARD SOUTH OF HONSHU. 
MODEL GUIDANCE IS IN POOR AGREEMENT DURING THE FIRST 48 HOURS WITH 
TWO DISTINCT SCENARIOS. THE FIRST SCENARIO FAVORS A NORTHWARD TRACK 
INTO SOUTHERN CHINA AND IS SUPPORTED BY JGSM AND EGRR (UKMO). THE 
SECOND SCENARIO IS A DIRECT NORTHEASTERLY TRACK AS FAVORED BY WBAR, 
GFS, AND GFDN. THE FIRST SCENARIO IS UNLIKELY DUE TO THE RESIDUAL 
STRENGTH OF THE ANTICYCLONE OVER SOUTHERN CHINA AND THE SECOND 
SCENARIO IS UNLIKELY DUE TO THE CURRENT MOTION OF 03W. THIS FORECAST 
CLOSELY APPROXIMATES CONSENSUS, ECMWF AND NOGAPS WHICH SPLIT THE TWO 
SCENARIOS THROUGH TAU 48 AND TRACK THE SYSTEM TO THE NORTH-NORTHEAST 
THROUGH THE TAIWAN STRAIT, AND THEN IT FAVORS THE NORTHEAST TRACK OF 
GFDN, GFS AND ECMWF. CONSENSUS IS SKEWED AFTER TAU 48 BY UKMO WHICH 
TRACKS THE SYSTEM INTO CENTRAL ASIA.
     C. BEYOND TAU 72, TS 03W IS EXPECTED TO ACCELERATE AND WEAKEN 
TO TROPICAL DEPRESSION STRENGTH DUE TO UNFAVORABLE UPPER-LEVEL 
NORTHEASTERLY WINDS ALOFT AND WILL BEGIN TO INTERACT WITH THE 
BAROCLINIC ZONE AROUND TAU 96.
FORECAST TEAM: ECHO//
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