A vigorous upper level trough closed off across the Southwest United States leading up to the outbreak of flash flooding across portions of Southwest Arkansas during the overnight hours of March 20th and morning hours of March 21st.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SHV wrote it up.
A vigorous upper level trough closed off across the Southwest United States leading up to the outbreak of flash flooding across portions of Southwest Arkansas during the overnight hours of March 20th and morning hours of March 21st.
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 Shreveport, LA wrote its last area forecast discussion before the first event at Mar 20, 10:47 PM CST, 13 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SHREVEPORT LA
1147 PM CDT TUE MAR 20 2012
.DISCUSSION...
SENT UPDATED PRODUCTS TO INCLUDE A HEADLINE FOR TORNADO WATCH 95. LATEST
MESOANALYSIS CONTINUES TO INDICATE INCREASING SRH IN THE LOWEST
LEVELS SOUTH OF THE I-20 AND EAST OF I-49. DIRECTIONAL SHEAR HAS
INCREASED AS WINDS HAVE BECOME MORE BACKED IN THE 0-1 KM LAYER PER
THE WINNFIELD PROFILER. ENHANCED TORNADO POTENTIAL REMAINS HIGHEST
IN THIS AREA SHOULD ANY STRONGER CONVECTION ORGANIZE. SINCE THIS IS
WHERE THE STRONGEST STORMS HAVE BEEN OCCURING...FLASH FLOOD THREAT
WILL ALSO BE HIGHEST IN THIS AREA OVER THE NEXT COUPLE OF HOURS. /09/
&&
.PREV DISCUSSION... /ISSUED 1006 PM CDT TUE MAR 20 2012/
DISCUSSION...
02Z LAPS ANALYSIS INDICATES A MAXIMUM IN 0-1 KM SRH OF IN NRN
NATCHITOCHES/SRN RED RIVER PARISHES. THIS INCREASE IN SRH SEEMS
REASONABLE AS LATEST SFC OBS ALSO INDICATES BACKED INFLOW WINDS
INTO THE CONVECTION IS THIS AREA. DEVELOPMENT OF 50 KT LLJ AT 850
MB ON THE 00Z KLCH RAOB AND WINNFIELD PROFILER WOULD ALSO SUPPORT
AN INCREASE IN SHEAR. THIS HAS LIKELY HELPED TO SUSTAIN STRONGER
CONVECTION COMING NORTH INTO THE CWA AND HAS LED TO SOME QUICK SPIN
UPS ACROSS THE SRN ZONES WITHIN THE STRONGER CONVECTION. THIS
MAXIMUM OF SRH HAS BEEN PROPAGATING NORTH IN A LOOP OF THE LAPS
ANALYSIS OVER THE LAST COUPLE OF HOURS. IF THIS CONTINUES TO
OCCUR...ISOLATED TORNADO THREAT MAY PERSIST FARTHER NORTH TOWARDS
THE I-20 CORRIDOR.
OTHERWISE...NO UPDATES ARE PLANNED FOR TONIGHT/S FCST. LATEST SAT
LOOPS INDICATE THE WARM CONVEYOR...AND CONSEQUENTLY THE CONVECTIVE
COMPLEX...HAS SLOWED IT/S EWD ADVANCEMENT. IN FACT...SOME WESTWARD
EXPANSION OF THE PRECIP HAS BEEN NOTICED. UPPER TROUGH IS STILL IN
THE PROCESS OF CUTTING OFF OVER W TX. DEPENDING ON WHERE THE LOW
WOBBLES OVER THE NEXT SEVERAL HOURS...THIS WILL BE KEY DETERMINING
WHERE THE BACK EDGE OF THE PRECIP SETS UP FOR THE NIGHT.
THEREFORE...HEAVY RAINFALL AND FLASH FLOODING WILL CONTINUE TO BE
A THREAT ACROSS MOST OF THE AREA THROUGH THE OVERNIGHT HOURS. /09/
AVIATION...
AXIS OF MODERATE TO HEAVY RAINFALL CONTINUING ACROSS ALL OF NORTHERN
LOUISIANA AND S AR ATTM. COLD POOL BOUNDARY HAS MOVED EAST OF THE
REGION BUT SFC TROUGH REMAINS STALLED THROUGH THE MIDDLE OF OUR FA
ATTM AND LIKELY NOT TO MOVE OVERNIGHT. CEILINGS CONTINUE FLUCTUATING
FROM MVFR TO MVFR AND OCCASIONAL IFR AND EXPECT THOSE CONDITIONS TO
CONTINUE AS WELL. WILL CONTINUE TO PREVAIL MOSTLY MVFR ACROSS THE
TERMINALS OVERNIGHT. TSRA REMAINS CONFINED TO S LA BUT CANNOT RULE
OUT ISOLATED TSRA AT ELD/MLU TERMINALS OVERNIGHT. CONDITIONS NOT
EXPECTED TO IMPROVE UNTIL WED AFTN ACROSS OUR E TX TERMINAL
LOCATIONS AND LIKELY NOT UNTIL LATE WED NIGHT ACROSS OUR E TERMINAL
LOCATIONS. /13/
PREV DISCUSSION... /ISSUED 321 PM CDT TUE MAR 20 2012/
DISCUSSION...
ACTIVE FORECAST FOR THE SHORT TERM WITH UPPER-LEVEL LOW PROGGED TO
DRIFT EAST ACROSS NORTH TEXAS BEFORE LIFTING NORTHEAST INTO
OKLAHOMA BY 06Z THURSDAY. BECAUSE OF THE SLOW NORTHEASTWARD PROGRESSION OF
THE UPPER-LOW...ALONG WITH THE SIGNIFICANT AMOUNTS OF RAINFALL
THAT HAVE ALREADY FALLEN ACROSS EAST TEXAS...WENT AHEAD AND
EXTENDED FLASH FLOOD WATCH THROUGH 00Z THURSDAY IN ADVANCE OF
THE NEXT ROUND OF RAINFALL. RE-INTENSIFICATION OF RAINFALL...MAINLY
OVERNIGHT TONIGHT INTO THURSDAY MORNING...TO OCCUR ACROSS NORTH
LOUISIANA AND SOUTHERN ARKANSAS...WITH A SECONDARY SURGE ACROSS
PORTIONS OF EAST TEXAS AND PORTIONS OF NORTHWEST LOUISIANA.
FOR THIS FORECAST...WENT AHEAD AND CANCELLED LAKE WIND ADVISORY
AND REMOVED A NUMBER OF PARISHES FROM TORNADO WATCH NUMBER 92.
EXPECTING CONTINUED TRAINING OF HEAVY RAINFALL ACROSS PORTIONS OF
NORTHEAST LOUISIANA AND SOUTHERN ARKANSAS OVER THE NEXT SEVERAL
HOURS.
EXPECT IMPROVING CONDITIONS ON THURSDAY AS UPPER LOW SLIDES EAST.
REMAINDER OF THE LONG TERM FORECAST APPEARS DRY AS UPPER-LEVEL
RIDGE BUILDS ACROSS THE FOUR STATE REGION. OTHERWISE...UNDER THE
INFLUENCE OF THE RIDGE...EXPECT HIGH TEMPERATURES TO APPROACH THE MID
80S ON SATURDAY. /05/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 54 62 48 74 54 / 80 70 40 10 10
MLU 63 65 48 72 54 / 100 100 60 20 10
DEQ 49 61 45 69 47 / 70 60 40 20 20
TXK 51 61 47 70 53 / 80 70 40 20 20
ELD 55 60 45 71 51 / 100 90 60 20 10
TYR 47 63 50 73 53 / 40 60 20 10 10
GGG 48 64 48 75 52 / 70 60 20 10 10
LFK 50 65 47 77 51 / 60 70 20 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR THE FOLLOWING
ZONES: ARZ050-051-059>061-070>073.
LA...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR THE FOLLOWING
ZONES: LAZ001>006-010>014-017>022.
OK...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR THE FOLLOWING
ZONES: OKZ077.
TX...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR THE FOLLOWING
ZONES: TXZ096-097-108>112-124>126-136>138-149>153-165>167.
&&
09HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE SHREVEPORT LA 1129 PM CDT TUE MAR 20 2012 ARZ050-051-059>061-070>073-LAZ001>003-010-OKZ077-TXZ096-097- 108>112-124>126-136>138-149>153-165>167-211200- SEVIER-HOWARD-LITTLE RIVER-HEMPSTEAD-NEVADA-MILLER-LAFAYETTE- COLUMBIA-UNION AR-CADDO-BOSSIER-WEBSTER-DE SOTO-MCCURTAIN- RED RIVER-BOWIE-FRANKLIN-TITUS-CAMP-MORRIS-CASS-WOOD-UPSHUR- MARION-SMITH-GREGG-HARRISON-CHEROKEE-RUSK-PANOLA-NACOGDOCHES- SHELBY-ANGELINA-SAN AUGUSTINE-SABINE TX- 1129 PM CDT TUE MAR 20 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARKANSAS...SOUTHWEST ARKANSAS...NORTHWEST LOUISIANA...SOUTHEAST OKLAHOMA...EAST TEXAS AND NORTHEAST TEXAS. .DAY ONE...TONIGHT... A FLASH FLOOD WATCH IS IN EFFECT UNTIL EARLY WEDNESDAY EVENING. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS MUCH OF EAST TEXAS...SOUTHEAST OKLAHOMA...SOUTHWEST ARKANSAS...AND NORTHWEST LOUISIANA TONIGHT. FLASH FLOODING WILL REMAIN POSSIBLE AS MORE STORMS REDEVELOP AND MOVE ACROSS AREAS THAT HAVE ALREADY RECEIVED HEAVY AMOUNTS OF RAINFALL OVER THE LAST 24 HOURS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY... SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH MUCH OF WEDNESDAY. THEREFORE...THE THREAT OF FLASH FLOODING WILL CONTINUE THROUGH WEDNESDAY EVENING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. LAZ004>006-011>014-017>022-211200- CLAIBORNE-LINCOLN-UNION LA-RED RIVER-BIENVILLE-JACKSON-OUACHITA- SABINE LA-NATCHITOCHES-WINN-GRANT-CALDWELL-LA SALLE- 1129 PM CDT TUE MAR 20 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL LOUISIANA AND NORTHWEST LOUISIANA. .DAY ONE...TONIGHT... A TORNADO WATCH IS IN EFFECT UNTIL 6 AM CDT WEDNESDAY MORNING. A FLASH FLOOD WATCH IS IN EFFECT UNTIL EARLY WEDNESDAY EVENING. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL CONTINUE TO AFFECT NORTH CENTRAL AND NORTHWEST LOUISIANA TONIGHT. A FEW STORMS MAY BECOME SEVERE THIS EVENING AND TONIGHT...ESPECIALLY ACROSS NORTH CENTRAL LOUISIANA. DAMAGING WINDS WILL BE THE PRIMARY THREAT...ALTHOUGH AN ISOLATED TORNADO CANNOT BE RULED OUT. IN ADDITION...RAINFALL MAY BE HEAVY AT TIMES AND IS EXPECTED TO CONTINUE INTO WEDNESDAY. FLASH FLOODING WILL CONTINUE TO BE POSSIBLE AS THUNDERSTORMS ARE EXPECTED TO CONTINUE TO DEVELOP AND MOVE ACROSS THE SAME AREAS OVER THE NEXT SEVERAL HOURS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY... SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH MUCH OF WEDNESDAY. THEREFORE...THE THREAT OF FLASH FLOODING WILL CONTINUE THROUGH EARLY WEDNESDAY EVENING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. 09
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
1014 PM CDT TUE MAR 20 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0900 PM FLASH FLOOD 9 ESE FLORIEN 31.40N 93.32W
03/20/2012 SABINE LA LAW ENFORCEMENT
WATER COVERING HWY 118 NEAR PEASON
&&
19PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
1016 PM CDT TUE MAR 20 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1010 PM BLIZZARD 8 N MANY 31.68N 93.47W
03/20/2012 SABINE LA LAW ENFORCEMENT
WATER COVERING HWY 175 NEAR BELMONT
&&
19PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
1018 PM CDT TUE MAR 20 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1010 PM FLASH FLOOD 1 N ZWOLLE 31.65N 93.64W
03/20/2012 SABINE LA LAW ENFORCEMENT
WATER COVERING OLD PLEASANT HILL ROAD NEAR ZWOLLE
&&
19PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE SHREVEPORT LA
1023 PM CDT TUE MAR 20 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1010 PM FLASH FLOOD 8 N MANY 31.68N 93.47W
03/20/2012 SABINE LA LAW ENFORCEMENT
WATER COVERING HWY 175 NEAR BELMONT
&&
19PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
1024 PM CDT TUE MAR 20 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1020 PM FLASH FLOOD COUSHATTA 32.02N 93.34W
03/20/2012 RED RIVER LA LAW ENFORCEMENT
NUMEROUS ROADS ARE FLOODED THROUGHOUT RED RIVER PARISH.
&&
15PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
1146 PM CDT TUE MAR 20 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1138 PM FLASH FLOOD NATCHITOCHES 31.76N 93.10W
03/20/2012 NATCHITOCHES LA TRAINED SPOTTER
ROYAL, TEXAS STREET UNDERPASS FLOODED. ISADORE STREET
FLOODED. BARACADES SET UP ON BIENVILLE STREET NEAR
NATCHITOCHES REGIONAL HOSPITAL.
&&
13The Shreveport radar (KSHV), 105 km away, was scanning. The volume nearest the first event began at 05:00 UTC.
4 flash flood. Local standard time, as filed.
County Road 15 was flooded and closed south of Magnolia, Arkansas.
County Road 54 was flooded and closed west of Magnolia, Arkansas.
Hwy. 19 and County Road 5 south of Magnolia, Arkansas were flooded and closed.
Flooding was reported at 19th and Greenbriar as well as at Wesson Road and Three Creek.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arkansas in 2012Every state in 2012This day in weather historyWarnings in Arkansas, March 2012
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: 362010, 362012, 362013, 362038.