As a warm front lifted northward across the forecast area, showers and storms developed. Some of the storms became severe with damaging winds and hail.
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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.
As a warm front lifted northward across the forecast area, showers and storms developed. Some of the storms became severe with damaging winds and hail.
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 Apr 9, 5:49 PM CST, 36 minutes earlier.
Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 649 PM CDT Fri Apr 9 2021 .SHORT TERM... (Through Late Saturday Night) Issued at 305 PM CDT Fri Apr 9 2021 An upper-level low will move into the Central Plains late this evening. In response to strengthening southerly flow ahead of the closed low, broad WAA will enable continuance and development of showers and thunderstorms across a destabilizing warm sector to the south of a warm front advancing northward into southern MO as well as a weak surface low across OK. These showers and thunderstorms will tend to move northeastward, likely toward the forecast area late this afternoon into tonight. A thunderstorm or two could become strong to severe with the presence of 30 to 40 kt of deep-layer vertical shear in place across the region. The latest SPC mesoanalysis indicates 1500 to 2500 J/kg of SBCAPE has developed across southeastern MO and southwestern IL this afternoon. Therefore, these locations will have the greatest chance of severe thunderstorms relative to the remainder of the forecast area. The main threat from thunderstorms will be gusty to possibly damaging winds and marginally severe hail. However, much higher probabilities of severe thunderstorms exist well south of the forecast area this afternoon into overnight. Overnight, showers will spread northeastward into the region as the upper-level closed low nears the Midwest and induces secondary surface cyclogenesis near southwestern MO with the warm front also lifting north. Depending on upstream convective evolution, a few elevated thunderstorms will remain possible overnight, especially along and south of I-70. But severe threat will be limited by stabilization of the environment across the region and much of this evening's steep mid-level lapse rates overturned by upstream convection. The surface low will continue to track northeastward approximately over the St. Louis metro Saturday morning. As the surface low passes, a brief break in showers is possible before another round of showers arrives by Saturday afternoon with a deformation band of precip to the northwest of the surface low as it deepens and matures. There could also be an isolated low-topped thunderstorm near the surface low center during the late morning across central and south- central IL with steep lapse rates beneath the upper- level closed low. Showers will likely continue into Saturday night, before the closed low and surface low depart the region. With abundant cloud cover and precip occurring through the majority of the day, Saturday's high temps will generally be below average, especially west of the Mississippi River. Locations beneath the deformation band may remain only remain around 50F Saturday. Gusty north- northwesterly to westerly winds of 30 to 35 kt will also be possible by Saturday afternoon as the surface low begins to exit. Higher wind gusts cannot be ruled out, but the magnitude of wind gusts will be dependent on how quickly the surface low deepens and pressure gradient tightens. Pfahler .LONG TERM... (Sunday through Next Friday) Issued at 305 PM CDT Fri Apr 9 2021 The upper-level closed low and associated surface low will continue to move northeast into the Great Lakes on Sunday, allowing upper- level ridging to occur over the Midwest with mid-level height rises. As this process occurs, low-level flow will begin to back from northwesterly to westerly upon approach of a weakening low-level ridge axis, allowing WAA to ensue. The combination of WAA and clearing skies will allow temps to rebound to above average for much of the forecast area on Sunday. Global model guidance is in somewhat better agreement on the progression of another upper-level closed low progged to enter the north-central U.S. Monday. There is increasing confidence that this closed low will force a weak cold front southeastward across the forecast area Monday into Monday night with a few rain showers becoming possible along the front as it encounters greater moisture present across the mid-Mississippi River Valley and Ohio Valley. Low- level convergence will likely be the main driver of these showers with most mid-level lift remaining attached to the closed low well north of the forecast area. This front will also likely mark the onset of an unseasonably cold airmass shunted southeastward by low- level northwesterly flow. Forecast uncertainty grows considerably beyond Monday with increasing spread among global model guidance with regard to how long the upper-level closed low meanders across the north-central U.S. These factors will affect how far south Monday's cold front advances and if it can retreat back to the north at any point during the middle of the week with the closed low advancing eastward. The evolution of the closed low and its impact on the behavior of the frontal boundary will dictate precip opportunities during this time period. Some GEFS and EPS members do not depict measurable precip beyond Monday and those that do differ substantially in timing. Therefore, only slight chance to chance PoPs can be justified at this juncture. However, there is much greater confidence that below average temps will prevail through the next week with low-level northwesterly to northerly flow likely prevailing. Pfahler && .AVIATION... (For the 00z TAFs through 00z Saturday Evening) Issued at 648 PM CDT Fri Apr 9 2021 An arcing band of rain and some isolated thunderstorms is moving northward across southern Missouri currently, and will impact the KCOU, KSUS, KSTL, and KCPS terminals later this evening. While I can't completely rule out a rumble of thunder, confidence in thunderstorms impacting these terminals remains low, so I will continue to forgo mention of thunder in the TAFs. This first band of rain is not expected to impact the KUIN terminal. Later tonight, widespread rain and IFR ceilings will overspread all terminals and continue through much of the remainder of the period, especially for the KCOU and KUIN terminals. For the KSUS, KSTL, and KCPS terminals, a break in the rain and increase to MVFR ceilings is expected tomorrow morning before another round of rain in the afternoon. For these terminals, IFR ceilings will are expected to remain just to their north. The final item of note is gusty winds tomorrow. During the morning, winds will gradually shift to generally out of the west and gust through the remainder of the period as an area of low pressure passes over Missouri and Illinois. If this low pressure is able to strengthen more than currently forecast, winds may be higher than currently indicated in the TAF, but confidence in this outcome is low at this time. Elmore && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 56 63 47 70 / 90 80 60 5 Quincy 49 52 45 65 / 90 90 80 5 Columbia 47 53 43 70 / 100 90 60 0 Jefferson City 49 55 43 72 / 100 90 60 0 Salem 59 67 47 69 / 90 80 40 10 Farmington 54 64 44 73 / 90 60 40 0 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service Saint Louis MO 310 PM CDT Fri Apr 9 2021 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-102015- 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- 310 PM CDT Fri Apr 9 2021 This Hazardous Weather Outlook is for portions of eastern and central Missouri as well as west central and southwest Illinois. .DAY ONE...Tonight. There is a chance of thunderstorms this afternoon into tonight along and south of Interstate 70. A few thunderstorms in southern Missouri and Illinois could become strong to severe late this afternoon and evening, with gusty to possibly damaging winds and marginally severe hail being the primary threats. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. There is a slight chance for thunderstorms late Saturday morning across central and south-central Illinois. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late this afternoon and evening. Pfahler
The St Louis radar (KLSX), 102 km away, was scanning. The volume nearest the first event began at 00:24 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds blew down several trees and numerous tree limbs between Tilden and Coulterville.
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, April 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: 951470.