A cutoff low helped to develop a round of afternoon thunderstorms. Some of the storms produced damaging winds.
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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 cutoff low helped to develop a round of afternoon thunderstorms. Some of the storms produced damaging winds.
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 25, 1:46 PM CST, 3 hours 51 minutes earlier.
Area Forecast Discussion National Weather Service Saint Louis MO 246 PM CDT Mon May 25 2020 .SHORT TERM... (Through Late Tuesday Night) Issued at 245 PM CDT Mon May 25 2020 The main forecast challenges will be convective trends both for the rest of this afternoon/evening and again on Tuesday. The culprit responsible for this wet weather is a trough to the west, soon to be a cutoff low as it deepens through the period. For the rest of this afternoon/evening, expect storms to continue to develop. The greatest concentration of storms is located within a weak area of PVA, whose ascent has helped to enhance some weak surface convergence across east-central MO. This is likely to be the most focused corridor of convection, although isolated to widely scattered convection is possible pretty much area-wide through the early evening hours. The atmosphere is not nearly as unstable as yesterday given a more moist profile (weaker lapse rates) and slightly lower surface temperatures. That being said, deep layer shear is a bit higher (20-25 knots of 0-6km shear) than yesterday, thus that may help to offset the lesser instability to some extent. Given the above factors, still expect a few strong to perhaps a localized severe storm this afternoon/evening capable of damaging wet microbursts due to heavy precipitation loading and perhaps an isolated instance of large hail. The damaging wind threat would be maximized with any storm clusters that can congeal into more of an east-west fashion which would help them utilize the deep layer wind field most favorably. In addition to these threats, a deep moist profile (PWATs around 1.7") suggests these storms will be efficient rainfall producers, which could lead to localized heavy rainfall and perhaps an isolated instance of flash flooding in areas where storms can train. Convection should wane tonight as we lose daytime heating. However, ensemble guidance is once again strongly suggestive that thunderstorms will redevelop during the day on Tuesday. Subtle shortwaves will be rotating around the deepening cutoff low, which will help foster additional bands of convection. Instability looks even weaker tomorrow, which should keep any severe threat generally at bay. However, we will need to continue to monitor for localized heavy rainfall as a very moist airmass will remain in place. Convection will once again mainly dissipate with the loss of daytime heating Tuesday evening. Deitsch .LONG TERM... (Wednesday through Next Monday) Issued at 229 PM CDT Mon May 25 2020 The synoptic pattern at the start of the long term period will feature a textbook Omega block across the CONUS, with the main feature being a pesky upper-level low spinning across the ArkLaTex region. This system will keep the pattern active through the end of the week, before it finally kicks off to the east and a drier regime settles in for this weekend. Wednesday will be similar to the past couple of days across the region. Weak shortwaves rounding the cutoff upper-level low will provide enough large scale ascent to foster thunderstorm development mainly in the afternoon and early evening hours. The latest ensemble and deterministic model suite are in fairly good agreement with a cold front pushing down from the northwest on Thursday. This convergent boundary, coupled with the upper-level support from the cutoff low will likely make Thursday the wettest day of the period (the most widespread convection), which is shown well in the probabilistic ensemble guidance from the National Blend of Models (NBM). The ensemble guidance is also in agreement that the surface front will slowly sag southeast of the region by Friday afternoon, finally allowing a much drier and cooler airmass to filter into the region Saturday into Sunday. If trends hold, it will be a very pleasant weekend with much lower humidity values and high temperatures in the mid to upper 80s. Deitsch && .AVIATION... (For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1208 PM CDT Mon May 25 2020 Main forecast concern will be thunderstorm timing and coverage this afternoon and evening. Have the highest confidence in storms at COU and UIN, where a TEMPO group for TSRA has been added. In the St. Louis metro area, confidence is a bit lower and thus have stuck with VCTS for now and will amend as confidence grows. Otherwise, convective coverage should diminish after the sun sets this evening, leaving a mainly dry and VFR overnight period. Winds will be out of the SE today into tonight around 5-10 knots, but gusts will increase to about 15 knots late Tuesday morning. SPECIFICS FOR KSTL: Main concern will be thunderstorm timing and coverage this afternoon into early this evening. Will continue with VCTS wording for now, but will continue to carefully monitor storm development in southeastern MO and whether that activity can expand and approach the STL terminal by 19-20Z. Otherwise, conditions should be dry and VFR tonight. Additional thunderstorms are possible on Tuesday afternoon. Winds through the period will be out of the SE at 5-10 knots, with higher gusts expected late Tuesday morning into Tuesday afternoon. Deitsch && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service Saint Louis MO 257 PM CDT Mon May 25 2020 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-262000- 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- 257 PM CDT Mon May 25 2020 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 for an isolated severe storm or two this evening capable of hail to the size of quarters and damaging winds to 60 mph. Additionally, locally heavy rainfall will be possible in any storm which could lead to localized flash flooding. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Additional thunderstorms are expected Tuesday through Friday. Storms will be capable of cloud to ground lightning and locally heavy rainfall. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening. Spotters are encouraged to report any severe weather, if observed, to the National Weather Service. Deitsch
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
349 PM CDT MON MAY 25 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0342 PM HAIL 3 NW GRAY SUMMIT 38.53N 90.85W
05/25/2020 E0.25 INCH FRANKLIN MO COCORAHS
&&
JPGPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
354 PM CDT MON MAY 25 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0327 PM TSTM WND DMG 2 ESE LOUISIANA 39.43N 91.02W
05/25/2020 PIKE MO DEPT OF HIGHWAYS
MODOT EMPLOYEE REPORTS TREE DOWN ON HIGHWAY
79 NEAR LOUISIANA.
&&
KDPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
442 PM CDT MON MAY 25 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0256 PM TSTM WND DMG 2 NNE DAVIS 39.08N 91.01W
05/25/2020 LINCOLN MO DEPT OF HIGHWAYS
MODOT EMPLOYEE REPORTS TREE DOWN OVER
HIGHWAY K. TIME ESTIMATED FROM RADAR.
&&
KDThe Lincoln radar (KILX), 82 km away, was scanning. The volume nearest the first event began at 23:37 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds uprooted a large tree in Virden. As it fell it clipped a house causing moderate damage. The tree was about 3 feet in diameter.
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: 887461.