50-knot winds, eye forming on 85GHz
Posted by JAC on 6/19/2009, 11:10 am
    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// NNNN |
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In this thread:
TS Linfa - hanna, 6/18/2009, 8:58 am
- Possible Taipei direct hit - JAC, 6/19/2009, 10:54 am
- Quasi-stationary - JAC, 6/19/2009, 7:08 am
- Fluctuating eye-wall development - JAC, 6/18/2009, 9:12 am
- Hot Core - JAC, 6/18/2009, 9:09 am
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