During the afternoon of May 16th, numerous supercells developed ahead of a cold front and within a favorable environment for high-end severe weather. These thunderstorms produced the St.
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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.
During the afternoon of May 16th, numerous supercells developed ahead of a cold front and within a favorable environment for high-end severe weather. These thunderstorms produced the St. Louis tornado which tracked into Madison County. Elsewhere, there were numerous reports of large hail and 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 16, 11:14 AM CST, 2 hours 26 minutes earlier. Its key messages:
Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1214 PM CDT Fri May 16 2025 .KEY MESSAGES... - Severe thunderstorms are expected to develop along or just ahead of a cold front this afternoon. Hail in excess of 2 inches in diameter and damaging winds in excess of 80 mph are the primary threats. A few tornadoes are also possible. If tornadoes do develop, they could be strong. - After a dry Saturday, the chance for rain returns Sunday and continues into next week, with the highest chances on Monday night and Tuesday. && .SHORT TERM... (Through Late Saturday Afternoon) Issued at 254 AM CDT Fri May 16 2025 The primary concern in the short term is the severe thunderstorm threat this afternoon. The environment this afternoon will be characterized by high CAPE and moderate to strong (mostly) linear deep-layer shear. All short range deterministic guidance develops 3000+ J/Kg MLCAPE and as much as 4000+ J/Kg by around 18Z this afternoon ahead of the front. 0-6km shear on all guidance is a respectable 50-60kts as well. Forecast soundings show steep (7.5- 8.5C/km) mid level lapse rates with 2000+ J/Kg CAPE in the hail growth zone. With that kind of instability and shear, rotating updrafts are very likely, and this kind of environment almost guarantees hail in excess of 2 inches. Low level lapse rates on forecast soundings are basically dry adiabatic with deep inverted-V signatures all the way to 850mb, so downdraft winds from supercells could produce wind gusts in excess of 80 mph. Linear shear will support splits and, depending on coverage, mergers leading to upscale growth. All this leads to a high confidence in severe weather this afternoon. With that said, where and when convective initiation will occur is still somewhat uncertain. The general consensus in most of the deterministic models, including most CAMs is that CI will occur between 18-20Z this afternoon over east central and southeast Missouri. The HRRR has been particularly consistent in showing this the past several runs. HREF probability of 2000+ J/Kg SBCAPE/>25 CINH/and 45kt+ 0-6km shear maxes out at around 60% during that period just west of the STL Metro area, extending southwest near the I-44 corridor. This lends confidence to an early/mid afternoon CI west of the Mississippi. There is a less likely scenario depicted by the deterministic GFS and ECMWF where CINH is stronger, and there isn't enough low level convergence along the front to initiate convection until later in the afternoon over far southeast Missouri and south central Illinois. To be clear, I think this scenario is less likely, but it is plausible. One way or another, forecast storm motion is 45-50kts, so even if the storms fire in east central Missouri, they should clear eastern portions of the CWFA by 22-00Z. The remainder of the short term looks quiet with the cold front moving down into Arkansas and the Tennessee Valley. Cooler and drier air will spill into the Mid Mississippi Valley tonight and Saturday. Lows Saturday morning will range from around 50 in northeast Missouri to the mid to upper 50s in the STL Metro and parts of southeast Missouri and southwest Illinois. Highs Saturday will be around 10 degrees cooler than Today in the mid 70s to around 80. Carney && .LONG TERM... (Saturday Night through Thursday) Issued at 254 AM CDT Fri May 16 2025 We look to continue with the active pattern into early next week as the LREF shows another upper low now moving into the Midwest by the middle of next week. The cluster analysis is showing some spread with regards to the track and the timing of the upper low which could affect potential heavy rainfall and strong to severe thunderstorms. We will begin to see the chances for showers and thunderstorms to slowly increase late Saturday night into Sunday as the LREF is showing a warm front beginning to move north from the Missouri/ Arkansas border. The chances will be highest on Sunday night and again Monday night when it is likely that a low level jet will set up the potential for MCSs to track along and north of the warm front and the LREF members have it's highest chances (70-90%) for rain both on Sunday/early Monday and Monday night/early Tuesday. Most of it's members are also producing rain as it brings a surface low and cold front through the area late Tuesday. I couldn't rule out a few hail producers with these MCSs given the forecast CAPE profiles and the deep layer shear. The deterministic GFS/ECMWF are showing MLCAPES in the 1000-1500 J/kg range with deep layer shear of 40-50 knots on Tuesday, so depending of the track of the upper low, a few strong to severe thunderstorms remain possible. The LREF is still advertising around a 60% chance of >2" of rainfall over the next 7 days over the entire area with only about of 10% of >4" of rainfall. Still, this higher chance is possible with any training thunderstorms that occur with the MCSs. The low will move off to the east by late next week and northwesterly flow will set up aloft. After temperatures mainly in the 70s and 80s Sunday into Tuesday, highs will fall off into the 60s for the mid to late next week. Britt && .AVIATION... (For the 18z TAFs through 18z Saturday Afternoon) Issued at 1210 PM CDT Fri May 16 2025 Isolated to scattered thunderstorms will develop along a cold front over the next couple of hours. The metro terminals still have the best chance, but coverage is too low to be confident enough to introduce a prevailing or a TEMPO. Any thunderstorm that does directly impact a terminal would have the capability of producing low visibilities in heavy downpours and large hail with some wind threat as well. Storms will move off to the east quickly, with dry weather and VFR conditions favored thereafter. Winds are expected to veer through this evening, with west/northwest winds behind the front. Gusts may diminish or at least weaken this evening before picking back up again by mid morning on Saturday. Gosselin && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service St Louis MO 509 AM CDT Fri May 16 2025 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-171015- Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL- Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL- Calhoun IL-Jersey IL-Madison IL-Saint Clair IL-Monroe IL-Knox MO- Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO- Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO- Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO- Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO- Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO- Madison MO-Reynolds MO- 509 AM CDT Fri May 16 2025 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. Severe thunderstorms are likely this afternoon across parts of east central and southeast Missouri into southwest and south central Illinois. Very large hail in excess of 2 inches in diameter, damaging wind gusts in excess of 80 mph, and a few tornadoes are all possible. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Thunderstorms are possible again late Saturday night through next Tuesday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and early this evening. Carney
Preliminary Local Storm Report
National Weather Service St Louis MO
207 PM CDT Fri May 16 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0205 PM Hail Washington 38.56N 91.02W
05/16/2025 E1.00 Inch Franklin MO Emergency Mngr
Washington EM reported 1-inch hail.
&&
MFPreliminary Local Storm Report
National Weather Service St Louis MO
210 PM CDT Fri May 16 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0200 PM Hail 2 SE New Melle 38.68N 90.86W
05/16/2025 E1.00 Inch St. Charles MO Public
Report from mPING: Quarter (1.00 in.).
&&
MFPreliminary Local Storm Report
National Weather Service St Louis MO
224 PM CDT Fri May 16 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0224 PM Hail 4 S Weldon Spring 38.66N 90.65W
05/16/2025 E1.75 Inch St. Louis MO Trained Spotter
&&
PfahlerPreliminary Local Storm Report
National Weather Service St Louis MO
225 PM CDT Fri May 16 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0224 PM Hail 1 NE Weldon Spring 38.73N 90.63W
05/16/2025 E1.25 Inch St. Charles MO Public
60 mph estimated winds as well.
&&
PfahlerPreliminary Local Storm Report
National Weather Service St Louis MO
232 PM CDT Fri May 16 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0229 PM Hail 3 E Chesterfield 38.65N 90.53W
05/16/2025 E1.00 Inch St. Louis MO Public
&&
MFPreliminary Local Storm Report
National Weather Service St Louis MO
238 PM CDT Fri May 16 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0225 PM Hail Harvester 38.75N 90.58W
05/16/2025 E2.00 Inch St. Charles MO Public
&&
MFThe St Louis radar (KLSX), 71 km away, was scanning. The volume nearest the first event began at 19:37 UTC.
14 thunderstorm wind, 11 hail, 1 tornado. Local standard time, as filed.
Thunderstorm winds felled trees and powerlines in the area.
Thunderstorm winds snapped numerous large trees in the area.
There were several reports of trees and power lines down over northern St. Clair County.
After crossing from St. Louis City, the tornado weakened. It caused EF-1 structural and tree damage in Granite City and Pontoon Beach before dissipating near Southern Illinois University - Edwardsville.
Quarter sized hail fell near Pontoon Road and Maryville Road in Granite City.
Thunderstorm winds snapped large tree branches near Highland.
Thunderstorm winds snapped one large tree branch from a large healthy tree.
Thunderstorm winds knocked down tree limbs that were 12 inches in diameter. The caller reported estimated winds of 70 mph.
Thunderstorm winds knocked a tree down across the intersection of Summerfield Road and Lilac Road.
Thunderstorm winds knocked one tree down. The tree took out a transformer and power pole as it fell.
Thunderstorm winds downed one large tree.
Thunderstorm winds downed trees near Route 16 and Route 127.
Thunderstorm winds uprooted a few small trees in Taylor Springs.
Thunderstorm winds downed multiple power poles in Patoka.
Thunderstorm winds caused tree damage of an unknown extent throughout Carlinville.
Thunderstorm winds caused the walls of a brick outbuilding to collapse after its roof was ripped off.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2025Every state in 2025This day in weather historyThe tornado archive for Illinois, 2025Warnings in Illinois, May 2025
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: 1262237, 1262238, 1262239, 1262242, 1262243, 1262235, 1262250, 1262251, 1262252, 1262253, 1262254, 1262255, 1262256, 1262257, 1262258, 1262259, 1262260, 1262274, 1262277, 1262280, 1262281, 1262282, 1262293, 1262283, 1262285, 1262287.