A few strong to severe storms developed north of a warm front during the afternoon and evening hours of May 16th.
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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 few strong to severe storms developed north of a warm front during the afternoon and evening hours of May 16th.
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 May 16, 11:54 AM CST, 1 hour 51 minutes earlier.
Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1254 PM CDT Sat May 16 2020 .SHORT TERM... (Through Late Sunday Afternoon) Issued at 340 AM CDT Sat May 16 2020 Early this morning, a low amplitude TROF was located over the High Plains, resulting in an unsettled southwest flow over our region. The main upper level storm system embedded within the TROF was over western Texas with additional weak upper level disturbances downstream and further northeast through southern Missouri. Another strong component within the TROF was located over Wyoming. At the surface, a weak wave of low pressure was located over the Oklahoma panhandle with a frontal boundary through Arkansas and the Mid South. There wasn't much precipitation in our region, but there were a few small clusters of showers and storms over southeastern Missouri and through the Lower Ohio Valley, indicative more of the elevated frontal boundary position. Temperatures were in the upper 50s and lower 60s with light east surface winds. The southern and main storm system is expected to track slightly north of east during this period, driving upper level disturbances through our region later today and this evening with lift from the main storm system itself late tonight and into Sunday. The old frontal boundary to our south is expected to buckle northward today but more over Kansas and far western Missouri than here, with our region expected to remain on the cool side during the day. WAA aloft will increase and with some heating of the day and the upper level disturbances rolling overhead, a general increase of shower and thunderstorm coverage is anticipated heading into the mid afternoon hours and continuing into the early evening. Limited instability and generally weak bulk shear will trim severe storm potential. Heading deeper into the night and into Sunday morning, coverage of showers should remain relatively high, but thunder should wane, eventually sliding slowly east by Sunday morning as the main cold front begins to enter the forecast area from the west. High amounts of clouds and what should be continued coverage of showers just ahead of the cold front will limit any renewed instability heading into the afternoon hours, but there is a small chance of seeing isolated strong-severe storms mainly east of the STL metro area during Sunday afternoon before all of the rain exits the far eastern sections of the forecast area by sunset. Leaned on the cool side of guidance for today with the front expected to stay south for most of the day, but higher than persistence, as some morning sunshine should allow for a slightly better warmup than yesterday. After a mild night tonight with south winds and cloudy skies and high dewpoints, temps will again be limited with ability to warmup on Sunday, especially west of the STL metro area with early cold FROPA. TES .LONG TERM... (Sunday Night through Friday) Issued at 340 AM CDT Sat May 16 2020 The GEFS H500 mean shows an emerging Omega Block pattern early in the period, as an amplified upper RIDGE develops over the Plains on Monday. The big difference with the GEFS H500 now from 24hrs ago is the upper LO to our north and where it tracks, directly affecting the longevity of the pattern. The upper LO is now favored to track further east, through Ohio, and will be displaced far enough east to preserve the Omega Block for much of the upcoming week, with the amplitude of the upper RIDGE de-amplifying some heading into late next week. Likewise, the GEFS surface mean shows a ridge of high pressure whose axis will be just northwest of our region at the start of the period with a slow southeastward translation to the lower Ohio Valley by Friday. The precipitation chances for Monday took a downward turn with the further east track of the upper LO. While the deep cyclonic flow will remain in place, it will not have the curvature advertised 24hrs ago and with less implied lift and a fairly dry column, rain chances should decline to 10% or less. Otherwise, the pattern for the rest of the week suggests one that is dry, or at the very least with rain chances that are too small to have any real skill at forecasting at this time. GEFS PW values show below average moisture in the column from all members until at the earliest late Thursday or Friday. Temperatures will begin the period below average and then slowly edge back to seasonable levels by late next week as suggested by both the position and strength of the GEFS mean surface ridge. TES && .AVIATION... (For the 18z TAFs through 18z Sunday Afternoon) Issued at 1236 PM CDT Sat May 16 2020 Short term aviation concerns are twofold: First, separate areas of showers will be approaching COU and UIN in the next few hours. There is some embedded thunder in both of areas of showers, but current trends indicate COU will not likely see any thunder until later in the afternoon. The second concern is the IFR/MVFR stratus deck across central and SE MO. Forecast guidance, which is not depicting the current situation very well, rapidly lifts the stratus to VFR in the early afternoon. Thus far, any lifting has been rather slow. Given guidance's poor performance thus far, have hung onto MVFR conditions at COU and the STL metro sites until the mid afternoon. Later this afternoon, isolated to scattered showers and storms are expected blossom across the region. The best shower and storm chances appear to be along and east of the Mississippi River, where fewer clouds have allowed the atmosphere to destabilize a bit more than elsewhere. Given the expected scattered nature of these storms, have just gone with vicinity thunder mention at the terminals. Should one of these storms impact a terminal, cigs and visbys will likely be briefly reduced until the storm moves out of the region. Precip activity should pick up in the overnight hours as a cold front moves into the area from the NW. Guidance in strong agreement dropping cigs around 1,000 ft and generating more widespread precipitation along and ahead of the front. Thunder is possible in this period, but I think it will be rather scattered given a lack of instability. BSH && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service Saint Louis MO 347 AM CDT Sat May 16 2020 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-171200- 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 IL-Saint Francois MO-Saint Louis City MO-Saint Louis MO- Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO- 347 AM CDT Sat May 16 2020 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 will become likely later this afternoon and early this evening for most areas. However, the probability for severe storms is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The chance for thunderstorms will continue on Sunday. Isolated strong to severe storms are possible for areas near and south and east of Saint Louis during Sunday afternoon. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. TES
The St Louis radar (KLSX), 94 km away, was scanning. The volume nearest the first event began at 19:46 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds caused minor roof damage to a residence about 2 miles northeast of Roodhouse.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2020Every state in 2020This day in weather historyWarnings in Illinois, May 2020
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: 887441.