A mesoscale convective complex moved across portions of eastern Missouri and west central/southwest Illinois. There were several reports of flash flooding, as well as a tornado.
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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 LSX wrote it up.
A mesoscale convective complex moved across portions of eastern Missouri and west central/southwest Illinois. There were several reports of flash flooding, as well as a tornado.
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 St. Louis, MO wrote its last area forecast discussion before the first event at Jul 31, 5:24 AM CST, 3 hours 17 minutes earlier.
Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 624 AM CDT Sat Jul 31 2021 .SHORT TERM... (Through Late Sunday Afternoon) Issued at 319 AM CDT Sat Jul 31 2021 Convection has initiated across Nebraska and Iowa, moving southeast along the MUCAPE gradient towards the CWA. Over the morning this area of convection is expected to congeal and continue to move southeast along the forward propagating Corfidi vectors, across northeast Missouri and into west-central Illinois by mid-morning. The SREF indicates the sharp MUCAPE gradient riding along the Mississippi River, with areas across Illinois largely devoid of instability and 1000-2000 J/kg of MUCAPE across central Missouri. While 30-35kts of 0-6 km shear will be available across northeast Missouri and west-central Illinois, the severe threat with these thunderstorms is low given the limited instability. What is of greater concern is the threat for locally heavy rainfall and localized flash flooding with this complex as it moves across the CWA. Operational and ensemble guidance indicates PWAT values of 1.5-2.0 inches across northeast Missouri and west-central Illinois, and 1.75-2.0+ inches across areas further south and west. This, combined with deep warm cloud layers near 4 km, and the potential for training convection, increases the potential for locally heavy rainfall and flash flooding. However, uncertainty still remains that the complex will hold together enough to produce significant precipitation over any particular spot. The complex is expected to exit the CWA by late afternoon if it can sustain itself that long along the MUCAPE boundary with cool, stable, post cold front air on the eastern side of the boundary. Confidence is low that the structure will be able to hold together all the way to the southeastern border of the CWA this afternoon. The CAMs are in good agreement that the outflow from this complex will lay out across southern Missouri and Illinois. New convective initiation then is possible during the late afternoon and evening along the outflow, forced by a mid-level disturbance along the outer edges of a trough aloft. Convection initiating along this boundary will be able to take advantage of the more unstable environment where the SREF guidance is showing 1000-2000 J/kg of MUCAPE. 30-35 kts of northwesterly 0-6 km shear could organize thunderstorms into line segments, a few strengthening to strong to severe, capable of producing heavy rainfall and damaging winds. The rapid advancement of the mid-level trough into the mid- Mississippi Valley will help push the outflow boundary and any lingering convection south of the area overnight. At the surface a high will push into the region, clearing out the sky and bringing drier air into the region. Temperatures today will be the coolest of the week, in the mid 70s to upper 80s, between the showers and thunderstorms across the area and associated cloud cover. Clearer skies on Sunday will help temperatures warm into the mid 80s across the area, but will still be below the normal 90 degrees for early August. MRM .LONG TERM... (Sunday Night through Friday) Issued at 319 AM CDT Sat Jul 31 2021 Ensemble and operational models are in agreement that the mid-level trough will remain locked in over the eastern US through the end of the period, keeping the forecast area in the persistent northwesterly flow along the western side of the trough. At the surface, an anticyclone will churn over the region, keeping conditions dry. Periodic mid-level shortwaves moving over the region will reinforce the cooler, dry air in the region while northeasterly low-level flow through mid-week will keep 850 mb temperatures in the low to mid teens. All of this translates to surface temperatures in the low to mid 80s through mid-week. By Thursday the low level anticyclone shifts slightly eastward, veering winds to the southwest once more. Warm air advection along this flow will start to rebound temperatures to near normal (90 degrees) by the end of the period. MRM && .AVIATION... (For the 12z TAFs through 12z Sunday Morning) Issued at 618 AM CDT Sat Jul 31 2021 Showers and thunderstorms are currently across northeast Missouri and west-central Illinois, moving southeast into east-central Missouri and southwest Illinois during the morning. Ahead of the showers and thunderstorms ceilings are dropping to low VFR, high MVFR flight conditions, while underneath thunderstorms, ceilings are dropping to fuel alternate and IFR flight conditions. Heavy rain is reducing visibility as well. Conditions are expected to improve as showers and thunderstorms move out of the area during the early afternoon, but uncertainty remains with how much of an improvement we'll see. By the end of the TAF period conditions will begin to clear as a surface high builds into the area. Winds will back to the north through the day as well as the thunderstorm complex moves through the area. MRM && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 79 67 84 63 / 80 30 5 0 Quincy 75 64 81 60 / 90 5 5 0 Columbia 83 65 83 61 / 40 20 5 0 Jefferson City 86 67 84 63 / 30 40 5 0 Salem 76 63 82 58 / 70 40 5 0 Farmington 86 66 83 60 / 40 70 5 0 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service Saint Louis MO 331 AM CDT Sat Jul 31 2021 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-010845- Adams IL-Audrain MO-Bond IL-Boone MO-Brown IL-Calhoun IL-Callaway MO- Clinton IL-Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO- Greene IL-Iron MO-Jefferson MO-Jersey IL-Knox MO-Lewis MO-Lincoln MO- Macoupin IL-Madison IL-Madison MO-Marion IL-Marion MO-Moniteau MO- Monroe IL-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-Pike IL- Pike MO-Ralls MO-Randolph IL-Reynolds MO-Saint Charles MO- Saint Clair-Saint Francois MO-Saint Louis City MO-Saint Louis MO- Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO- 331 AM CDT Sat Jul 31 2021 This Hazardous Weather Outlook is for portions of eastern and central Missouri as well as west central and southwest Illinois. .DAY ONE...Today and tonight. Thunderstorms are likely across the area today and tonight, with damaging winds and locally heavy rainfall the main threats. .DAYS TWO THROUGH SEVEN...Sunday through Friday. A few thunderstorms could linger across far southern Missouri early Sunday morning. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any severe weather, if observed, to the National Weather Service as well as rainfall amounts in excess of an inch or any flooding. MRM
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
817 AM CDT SAT JUL 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0817 AM FLASH FLOOD 1 ENE HANNIBAL 39.71N 91.37W
07/31/2021 MARION MO LAW ENFORCEMENT
WATER OVER THE ROADWAY AT HIGHWAY 61 AND
ROSS IN HANNIBAL, MO. THE ROADWAY IS CLOSED.
&&
KDPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
818 AM CDT SAT JUL 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0745 AM FLOOD 2 SE BARING 40.22N 92.18W
07/31/2021 KNOX MO TRAINED SPOTTER
A FEW INCHES OF WATER OVER THE ROADWAY ALONG
HIGHWAY 15. THE ROADWAY REMAINS OPEN.
&&
KDPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
916 AM CDT SAT JUL 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0915 AM FLASH FLOOD 1 E HANNIBAL 39.70N 91.36W
07/31/2021 MARION MO LAW ENFORCEMENT
WATER OVER THE ROADWAY AT 7TH STREET NEAR
WARREN BARRETT IN HANNIBAL, MO.
&&
KDThe St Louis radar (KLSX), 84 km away, was scanning. The volume nearest the first event began at 14:40 UTC.
1 flash flood. Local standard time, as filed.
Up to four inches of rain fell in a short amount of time causing flash flooding. Several roads were flooded including Illinois Route 108 near Carrollton and Daum-Station Road south southwest of Wrights.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2021Every state in 2021This day in weather historyWarnings in Illinois, July 2021
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: 975907.