Alert archive / Illinois / Severe Thunderstorm Warnings in 2024

Severe Thunderstorm Warning 124, NWS St. Louis, MO

April 18, 2024Jersey County, Madison County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Apr 18, 2024, 5:18 PM CDT for Jersey County, Madison County, Illinois. It was in force for 27 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 18, 2024, 5:18 PM CDT (22:18 UTC)
Expired: Apr 18, 2024, 5:45 PM CDT
In force: 27 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Jersey County, IL, Madison County, IL

The radar

The St Louis radar (KLSX), 40 km from the middle of the area, began a volume at 22:21 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 18, 12:56 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.3 hours before the alert went out and 200 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1827 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 90 m²/s²
0-3 km storm-relative helicity: 269 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

103 
WUUS53 KLSX 182218
SVRLSX
ILC083-119-182245-
/O.NEW.KLSX.SV.W.0124.240418T2218Z-240418T2245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
518 PM CDT Thu Apr 18 2024

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Northwestern Madison County in southwestern Illinois...
  Southern Jersey County in southwestern Illinois...

* Until 545 PM CDT.

* At 518 PM CDT, a severe thunderstorm was located over Grafton,
  moving east at 50 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Alton, Godfrey, Grafton, and Elsah.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3887 9015 3889 9020 3892 9025 3893 9028
      3892 9031 3896 9041 3897 9048 3899 9057
      3902 9058 3903 9057 3900 9015
TIME...MOT...LOC 2218Z 270DEG 45KT 3899 9045 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

CVKING

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at Apr 18, 2:37 PM CDT, 2 hours 41 minutes earlier. Its key messages:

The threat for strong to severe thunderstorms will continue across the area until approximately 0200 UTC. All hazards (large hail, damaging winds, isolated tornadoes) are on the table, though there should be a transition more from large hail to damaging winds by this evening.
Seasonably cool and mostly dry weather is forecast through the weekend, with frost potential both Saturday and Sunday nights.

Area forecast discussion, Apr 18, 2:37 PM CDT, 2 hours 41 minutes before

Area Forecast Discussion
National Weather Service Saint Louis MO
237 PM CDT Thu Apr 18 2024

.KEY MESSAGES...

- The threat for strong to severe thunderstorms will continue
  across the area until approximately 0200 UTC. All hazards
  (large hail, damaging winds, isolated tornadoes) are on the
  table, though there should be a transition more from large hail
  to damaging winds by this evening.

- Seasonably cool and mostly dry weather is forecast through the
  weekend, with frost potential both Saturday and Sunday nights.

&&

.SHORT TERM...  (Through Late Friday Night)
Issued at 235 PM CDT Thu Apr 18 2024

The earlier outflow boundary has largely washed out, with the focus
for convection moreso along the synoptic cold front early this
afternoon. A couple of supercells have developed in western
Missouri, with additional development along the front further
northeast into northeast Missouri and west-central Illinois.
Right-moving supercells may tend to ride the frontal boundary as
it pushes eastward while non supercells and any left movers would
tend to cut across the front (and therefore may weaken). The
rather linear forcing along the cold front also should tend more
toward line/bowing segments, with damaging winds the growing
concern late this afternoon into early this evening. Speaking of
the cold front, it was nearing a KJLN>>KCOU>>KI63 line as of 1900
UTC, and will continue to progress to the east, likely exiting
the far southeastern CWA around 0100-0200 UTC. While there likely
will be some elevated shower and thunderstorm activity behind it,
anything behind the front should not be severe.

Strong low-level cold air advection settles in behind the frontal
boundary overnight tonight, with lows dropping back into the upper
30s to upper 40s from northwest to southeast. These readings would
be near to slightly below normal for mid/late April. Dry conditions
along with continued seasonably cool temperatures are forecast to
continue Friday and Friday night.

Gosselin

&&

.LONG TERM...  (Saturday through Next Thursday)
Issued at 235 PM CDT Thu Apr 18 2024

(Saturday - Sunday Night)

There is little/no change in the synoptic pattern through this
weekend, with broad surface high pressure over the Mississippi
Valley. Persistent below normal temperatures (roughly 5-10 degrees)
are expected both day and night. We will have to watch for frost
development both Saturday and Sunday night given the light/variable
winds expected. There may be more clouds Saturday night (especially
in parts of southeast Missouri and southwest Illinois), with a
better chance of a widespread clear sky Sunday night. Lows in the
mid to upper 30s are forecast each night, favoring the development
of areas to potentially widespread frost if it is clear.

(Monday - Next Thursday)

Temperatures are expected to moderate early next week as mid/upper
level heights rise and 850-hPa temperatures climb back closer to
+5C. Ensemble guidance shows a midlevel shortwave trough moving
across the Upper Midwest Monday night into Tuesday, with a cold
front draped to its southwest. This front is likely to move through
the area late Tuesday/Tuesday evening, bringing a chance of showers
and perhaps a few thunderstorms. Behind the front, slightly cooler
and drier weather is favored for midweek next week.

Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1206 PM CDT Thu Apr 18 2024

Chances of showers and thunderstorms will gradually increase over
the next several hours along/ahead of a cold front. The best
chance for storms at KUIN/KCOU/KJEF is mid-late afternoon, and
closer to 0000 UTC in/around metro St. Louis. Hail, strong winds,
and very low visibilities are all possible in thunderstorms. Some
trailing shower activity may linger for a few hours behind the
cold front, with ceilings lowering to low MVFR along with a wind
shift to the northwest. A brief period of IFR ceilings is
possible this evening/early overnight, but was not confident
enough to add in at this time.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

WFO LSX

Hazardous weather outlook, Apr 18, 2:39 PM CDT, 2 hours 39 minutes before

Hazardous Weather Outlook
National Weather Service St Louis MO
239 PM CDT Thu Apr 18 2024

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-191945-
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-
239 PM CDT Thu Apr 18 2024

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Tonight.

Thunderstorms are likely today across most of the area through this
evening. Some of the thunderstorms through early evening may be
severe, capable of producing damaging winds, large hail, and a
tornado or two.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

There is a chance of thunderstorms over parts of the area on Monday
night through Tuesday night.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report any form of severe weather to the
National Weather Service in St. Louis.

Gosselin

In the hours before

Local storm report, Apr 18, 4:16 PM CDT, 1 hour 2 minutes before

Preliminary Local Storm Report
National Weather Service St Louis MO
416 PM CDT Thu Apr 18 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0411 PM     Hail             5 W Silex               39.13N 91.14W
04/18/2024  M1.00 Inch       Lincoln            MO   Public

&&

BRC

Local storm report, Apr 18, 4:22 PM CDT, 56 minutes before

Preliminary Local Storm Report
National Weather Service St Louis MO
422 PM CDT Thu Apr 18 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     Hail             4 SE New Hartford       39.15N 91.23W
04/18/2024  E1.00 Inch       Pike               MO   Public

&&

BRC

Local storm report, Apr 18, 4:32 PM CDT, 46 minutes before

Preliminary Local Storm Report
National Weather Service St Louis MO
432 PM CDT Thu Apr 18 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0428 PM     Hail             3 E Silex               39.13N 91.00W
04/18/2024  E1.00 inch       Lincoln            MO   Emergency Mngr

            time estimate from radar.

&&

MMG

Local storm report, Apr 18, 4:40 PM CDT, 38 minutes before

Preliminary Local Storm Report
National Weather Service St Louis MO
440 PM CDT Thu Apr 18 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0437 PM     Hail             Roodhouse               39.48N 90.37W
04/18/2024  M1.00 Inch       Greene             IL   Trained Spotter

&&

Local storm report, Apr 18, 4:44 PM CDT, 34 minutes before

Preliminary Local Storm Report
National Weather Service St Louis MO
444 PM CDT Thu Apr 18 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0436 PM     Hail             1 NNE White Hall        39.45N 90.40W
04/18/2024  E1.00 Inch       Greene             IL   Trained Spotter

&&

BRC

Local storm report, Apr 18, 5:01 PM CDT, 17 minutes before

Preliminary Local Storm Report
National Weather Service St Louis MO
501 PM CDT Thu Apr 18 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     Hail             3 ENE Roodhouse         39.51N 90.33W
04/18/2024  E1.75 Inch       Greene             IL   Public

            Observer also reported a horizontal roll
            cloud.

&&

MF

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 18, 3:23 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Pike	52 min
Apr 18, 3:49 PM CDT	Tornado Warning	LSX	Pike	26 min
Apr 18, 4:03 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Greene	57 min
Apr 18, 4:16 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Calhoun	44 min
Apr 18, 4:25 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Greene	50 min
Apr 18, 4:40 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun	50 min
Apr 18, 4:47 PM CDT	Severe Thunderstorm Warning	LSX	Macoupin	58 min
Apr 18, 4:48 PM CDT	Tornado Warning	LSX	Calhoun	42 min
Apr 18, 4:52 PM CDT	Severe Thunderstorm Warning	LSX	Greene, Jersey	38 min
Apr 18, 5:01 PM CDT	Tornado Warning Tornado observed	LSX	Greene, Macoupin	29 min
Apr 18, 5:07 PM CDT	Tornado Warning	LSX	Greene, Jersey	23 min
Apr 18, 5:25 PM CDT	Severe Thunderstorm Warning	LSX	Madison, Saint Clair	65 min
Apr 18, 5:26 PM CDT	Tornado Warning	LSX	Macoupin	34 min
Apr 18, 5:30 PM CDT	Severe Thunderstorm Warning	LSX	Greene, Jersey, Macoupin	60 min
Apr 18, 5:34 PM CDT	Tornado Warning	LSX	Greene, Jersey, Macoupin	26 min
Apr 18, 5:37 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Monroe	53 min
Apr 18, 5:39 PM CDT	Severe Thunderstorm Warning	LSX	Madison, Monroe, Saint Clair	66 min
Apr 18, 5:45 PM CDT	Tornado Warning	LSX	Macoupin, Montgomery	45 min
Apr 18, 5:45 PM CDT	Tornado Warning	LSX	Madison	45 min
Apr 18, 5:49 PM CDT	Tornado Warning	LSX	Monroe, Saint Clair	41 min
Apr 18, 5:53 PM CDT	Areal Flood Advisory	LSX	Greene, Macoupin	2 hr
Apr 18, 5:56 PM CDT	Tornado Warning	LSX	Macoupin, Madison	49 min
Apr 18, 5:59 PM CDT	Tornado Warning	LSX	Macoupin	31 min
Apr 18, 6:10 PM CDT	Tornado Warning	LSX	Bond, Clinton, Madison, Saint Clair, Washington	65 min
Apr 18, 6:13 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Randolph, Saint Clair, Washington	77 min
Apr 18, 6:14 PM CDT	Tornado Warning	LSX	Montgomery	46 min
Apr 18, 6:34 PM CDT	Tornado Warning	LSX	Monroe, Randolph	41 min
Apr 18, 6:41 PM CDT	Tornado Warning	LSX	Fayette	49 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2024 Every severe thunderstorm warning in 2024

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.