Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 148, NWS St. Louis, MO

August 12, 20216 counties in Illinois; Jefferson County, Sainte Genevieve County, Saint Francois County, Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Aug 12, 2021, 7:14 PM CDT for 6 counties in Illinois; Jefferson County, Sainte Genevieve County, Saint Francois County, Missouri. It was in force for 61 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 12, 2021, 7:14 PM CDT (00:14 UTC)
Expired
Aug 12, 2021, 8:15 PM CDT
In force
61 min
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Damage threat
Considerable
Hail
0.75 in
Wind
70.0 mph

Counties Clinton County, IL, Madison County, IL, Monroe County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, Jefferson County, MO, Saint Francois County, MO, Sainte Genevieve County, MO

The radar

The St Louis radar (KLSX), 103 km from the middle of the area, began a volume at 00:17 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.

What was reported inside it

TimeReportWhereRemark
Aug 12, 7:20 PM CDTTSTM WND DMG3 Nnw Freeburg, ILPOWER LINES BLOWN DOWN AT THE INTERSECTION OF ILLINOIS ROUTE 15 AND JEFFERSON ROAD.
Aug 12, 7:22 PM CDTTSTM WND DMGFreeburg, ILNUMEROUS TREES AND TREE LIMBS BLOWN DOWN AROUND TOWN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

IssuedProductOfficeLasted
Aug 12, 5:19 PM CDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 0.2 hours before the alert went out and 250 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-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2021-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2021-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 34 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1699 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
34 m²/s²
0-3 km storm-relative helicity
89 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

932 
WUUS53 KLSX 130014
SVRLSX
ILC027-119-133-157-163-189-MOC099-186-187-130115-
/O.NEW.KLSX.SV.W.0148.210813T0014Z-210813T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
714 PM CDT Thu Aug 12 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Southern Clinton County in south central Illinois...
  Southern Monroe County in southwestern Illinois...
  Southeastern Madison County in southwestern Illinois...
  Washington County in south central Illinois...
  Randolph County in southwestern Illinois...
  St. Clair County in southwestern Illinois...
  Southeastern Jefferson County in east central Missouri...
  Ste. Genevieve County in southeastern Missouri...
  Northwestern St. Francois County in southeastern Missouri...

* Until 815 PM CDT.

* At 712 PM CDT, severe thunderstorms were located along a line
  extending from Shiloh to New Design to near De Soto, moving
  southeast at 50 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...This line of storms has a history of damaging wind gusts.

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings.

* Severe thunderstorms will be near...
  Mascoutah, Lebanon, Red Bud and Scott AFB around 720 PM CDT.
  New Baden around 725 PM CDT.
  Albers, Evansville, Baldwin and New Memphis around 730 PM CDT.

Other locations in the path of these severe thunderstorms include
Bloomsdale, Rocky Ridge, Sparta, Okawville, Weingarten, Ste.
Genevieve, Nashville, Steeleville, Percy, Chester and St. Mary.

This includes the following highways...
 Interstate 64 in Illinois between exits 14 and 61.
 Interstate 55 in Missouri between exits 141 and 174.

This also includes Hawn State Park and Felix Valle House State Park.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3822 8959 3795 8960 3781 8967 3785 8979
      3791 8984 3783 8999 3767 9011 3810 9068
      3829 9017 3875 8983 3849 8914 3821 8915
TIME...MOT...LOC 0012Z 298DEG 43KT 3856 8989 3825 9009 3810 9052 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Elmore
1 follow-up statement
084 
WWUS53 KLSX 130054
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
754 PM CDT Thu Aug 12 2021

ILC119-133-MOC099-187-130103-
/O.CAN.KLSX.SV.W.0148.000000T0000Z-210813T0115Z/
Monroe IL-Madison IL-Jefferson MO-St. Francois MO-
754 PM CDT Thu Aug 12 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN MONROE AND
SOUTHEASTERN MADISON COUNTIES IN SOUTHWESTERN ILLINOIS...SOUTHEASTERN
JEFFERSON COUNTY IN EAST CENTRAL MISSOURI AND NORTHWESTERN ST.
FRANCOIS COUNTIES IN SOUTHEASTERN MISSOURI IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
south central and southwestern Illinois...and southeastern and east
central Missouri.

LAT...LON 3821 8915 3822 8959 3795 8960 3781 8968
      3791 8984 3783 8999 3767 9011 3791 9042
      3798 9032 3804 9041 3806 9038 3813 9025
      3809 9020 3813 9004 3823 9001 3822 8990
      3828 8992 3866 8973 3866 8959 3849 8914
TIME...MOT...LOC 0053Z 298DEG 43KT 3834 8937 3803 8957 3788 9000 

$$

ILC027-157-163-189-MOC186-130115-
/O.CON.KLSX.SV.W.0148.000000T0000Z-210813T0115Z/
Clinton IL-Washington IL-Randolph IL-St. Clair IL-Ste. Genevieve MO-
754 PM CDT Thu Aug 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR SOUTHERN CLINTON...WASHINGTON...RANDOLPH...EASTERN ST. CLAIR AND
STE. GENEVIEVE COUNTIES...

At 753 PM CDT, severe thunderstorms were located along a line
extending from Nashville to near Percy to near St. Mary, moving
southeast at 50 mph.

HAZARD...60 mph wind gusts.

SOURCE...This line of storms has a history of damaging wind gusts.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
  Nashville and Ashley.

This also includes Hawn State Park and Felix Valle House State Park.
 
This includes the following highways...
 Interstate 64 in Illinois between exits 27 and 61.
 Interstate 55 in Missouri between exits 141 and 162.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3821 8915 3822 8959 3795 8960 3781 8968
      3791 8984 3783 8999 3767 9011 3791 9042
      3798 9032 3804 9041 3806 9038 3813 9025
      3809 9020 3813 9004 3823 9001 3822 8990
      3828 8992 3866 8973 3866 8959 3849 8914
TIME...MOT...LOC 0053Z 298DEG 43KT 3834 8937 3803 8957 3788 9000 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Elmore

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 12, 7:40 PM CDTFlash Flood WarningLSXBond, Madison4 hr
Aug 13, 9:33 AM CDTRiver Flood WarningLSXLewis13 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2021Severe Thunderstorm Warnings in Missouri, 2021Every severe thunderstorm warning in 2021

Sources

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