A weakening mesoscale convective system moved into the Mid-South during the day on August 20th, 2009. Additional showers and thunderstorms redeveloped over the area along old convective boundaries from the system during the evening hours.
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The episode as NWS MEG wrote it up.
A weakening mesoscale convective system moved into the Mid-South during the day on August 20th, 2009. Additional showers and thunderstorms redeveloped over the area along old convective boundaries from the system during the evening hours. Some thunderstorms produced locally heavy rainfall which caused flash flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Memphis, TN wrote its last area forecast discussion before the first event at Aug 20, 5:01 PM CST, 2 hours 54 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 601 PM CDT THU AUG 20 2009 .PREV DISCUSSION... /ISSUED 245 PM CDT THU AUG 20 2009/ A COUPLE OF AREAS OF RAIN ARE MOVING ACROSS PORTIONS OF THE FORECAST AREA THIS AFTERNOON. FIRST AREA OF THUNDERSTORMS IS MOVING ACROSS PORTIONS OF NORTHEAST MISSISSIPPI WHILE ANOTHER AREA OF RAIN IS MOVING ACROSS PORTIONS OF NORTHEAST ARKANSAS AND THE MISSOURI BOOTHEEL. TEMPERATURES VARY QUITE A BIT ACROSS THE FORECAST AREA THIS AFTERNOON BASED ON PREVIOUS RAINFALL AND CLOUD COVER WITH READINGS FROM THE LOWER 70S TO MID 80S. COLD FRONT CURRENTLY EXTENDS FROM NEAR CHICAGO THROUGH CENTRAL MISSOURI AND INTO NORTHWEST TEXAS. THIS FRONT WILL MOVE THROUGH THE FORECAST AREA TONIGHT BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. ANY THREAT OF SEVERE WEATHER IS CONFINED TO MAINLY NORTH MISSISSIPPI AND THE ATMOSPHERE DOWN THERE IS RELATIVELY STABLE DUE TO THE THUNDERSTORMS THAT HAVE ALREADY COME THROUGH. SOME LOCALLY HEAVY DOWNPOURS ARE POSSIBLE THIS EVENING BUT THERE IS NOT ENOUGH OF A THREAT TO WARRANT A FLASH FLOOD WATCH. THE COLD FRONT SHOULD BE JUST SOUTH OF THE FORECAST AREA BY FRIDAY MORNING SO THERE MAY BE A FEW THUNDERSTORMS IN THE EXTREME SOUTHERN PART OF THE FORECAST AREA. BY FRIDAY AFTERNOON...DRIER AIR SHOULD MOVE INTO THE REGION BRINGING THE START OF A NICE WEEKEND WITH NO RAIN EXPECTED AND TEMPERATURES SEVERAL DEGREES BELOW NORMAL. BY MONDAY...HIGH PRESSURE WILL HAVE MOVED EAST OF THE FORECAST AREA BRINGING A RETURN OF SOUTH WINDS TO THE REGION AND A SLOW WARMING TREND WHICH WILL CONTINUE FROM MONDAY THROUGH THURSDAY WHILE DRY WEATHER SHOULD PREVAIL DURING THAT TIME. ARS && .AVIATION... 00Z TAF SET BIG QUESTION WITH THIS TAF SET WILL BE THE POTENTIAL FOR REDEVELOPMENT OF TSRA ALONG THE COLD FRONT. IN THE LAST 15 MINUTES A FEW QUICK MOVING SHRA HAVE DEVELOPED NEAR KJBR. IN ADDITION...A LINE OF SHRA HAS BEEN TRYING TO DEVELOP OVER SOUTHERN MO BUT HAS BEEN HAVING A HARD TIME GETTING GOING. THIS LINE IS WHERE THE FRONT IS CURRENTLY LOCATED. EXPECT THE DEVELOPMENT OVER NE AR AND SOUTHERN MO EVENTUALLY WILL COME TOGETHER AND FORM AN AREA OF SHRA AND TSRA. KJBR WILL LIKELY BE AFFECTED FROM NOW THROUGH 07Z WHILE BEST TIMING FOR KMEM AND KMKL WILL BE BETWEEN 05-9Z...AND KTUP BETWEEN 10-14Z. SOME LINGERING SHRA MAY OCCUR FOR A FEW HOURS THEREAFTER BEFORE SOME CLEARING OCCURS. CU DEVELOPMENT WILL LIKELY OCCUR AFTER 16-18Z TOMORROW BEHIND THE FRONT. WINDS WILL BE GENERALLY AROUND 5-7 KTS FROM THE S OR SW AHEAD OF FRONT SWITCHING TO THE NW BEHIND THE FRONT. SPEEDS WILL INCREASE TO 12 KTS AFTER 18Z. KRM && && .PRELIMINARY POINT TEMPS/POPS... MEM 71 86 65 82 / 70 10 10 0 MKL 67 86 61 81 / 70 10 10 0 JBR 67 85 61 81 / 70 10 0 0 TUP 72 87 64 85 / 70 30 10 0 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. &&
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE MEMPHIS TN 307 PM CDT THU AUG 20 2009 ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115- MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-212215- ALCORN-BENTON MS-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA- CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DESOTO-DECATUR-DUNKLIN-DYER- FAYETTE-GIBSON-GREENE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON-HENRY- ITAWAMBA-LAFAYETTE-LAKE-LAUDERDALE-LAWRENCE-LEE AR-LEE MS-MADISON- MARSHALL-MCNAIRY-MISSISSIPPI-MONROE-OBION-PANOLA-PEMISCOT- PHILLIPS-POINSETT-PONTOTOC-PRENTISS-QUITMAN-RANDOLPH-SHELBY- ST. FRANCIS-TALLAHATCHIE-TATE-TIPPAH-TIPTON-TISHOMINGO-TUNICA- UNION-WEAKLEY-YALOBUSHA- 307 PM CDT THU AUG 20 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST ARKANSAS... THE MISSOURI BOOTHEEL...NORTH MISSISSIPPI...AND WEST TENNESSEE. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEMPHIS TN
534 PM CDT THU AUG 20 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0855 PM FLASH FLOOD 4 E DECATURVILLE 35.58N 88.05W
08/19/2009 DECATUR TN EMERGENCY MNGR
5 LOW WATER CROSSING FLOODED.
&&
MBSThe national radar mosaic for the moment the first event began.
1 flash flood. Local standard time, as filed.
Heavy rain produced flash flooding in and around Decatur County. Five low water crossings were flooded as a result.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2009Every state in 2009This day in weather historyWarnings in Tennessee, August 2009
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 192949.