Alert archive / Missouri / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 87, NWS St. Louis, MO

June 20, 20214 counties in Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Jun 20, 2021, 10:55 PM CDT for 4 counties in Missouri. It was in force for 35 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: Jun 20, 2021, 10:55 PM CDT (03:55 UTC)
Expired: Jun 20, 2021, 11:30 PM CDT
In force: 35 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 70.0 mph

Counties Audrain County, MO, Boone County, MO, Callaway County, MO, Montgomery County, MO

The radar

The St Louis radar (KLSX), 93 km from the middle of the area, began a volume at 03:56 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

Time	Report	Where	Remark
Jun 20, 10:57 PM CDT	TSTM WND DMG	5 Ese Kingdom City, MO	CORRECTS PREVIOUS TSTM WND DMG REPORT FROM 5 ESE KINGDOM CITY. TREE OVER Z HIGHWAY.
Jun 20, 11:17 PM CDT	TSTM WND DMG	Montgomery City, MO	LARGE TREE BLOWN DOWN ON W 6TH STREET.

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.

Issued	Product	Office	Lasted
Jun 20, 8:10 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Springfield, MO (KSGF), launched 00:00Z, 3.9 hours before the alert went out and 287 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: 1346 J/kg
Mixed-layer CIN: -132 J/kg
Mixed-layer LCL: 1683 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 81 m²/s²
0-3 km storm-relative helicity: 264 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 5.8

Open this sounding in Storm Lab

The text

As transmitted.

172 
WUUS53 KLSX 210355
SVRLSX
MOC007-019-027-139-210430-
/O.NEW.KLSX.SV.W.0087.210621T0355Z-210621T0430Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
1055 PM CDT Sun Jun 20 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Northern Boone County in central Missouri...
  Southern Audrain County in central Missouri...
  Montgomery County in east central Missouri...
  Callaway County in central Missouri...

* Until 1130 PM CDT.

* At 1054 PM CDT, severe thunderstorms were located along a line
  extending from Martinsburg to 6 miles south of Fulton, moving east
  at 55 mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Trained weather spotters. At 10:25 pm multiple trees and 
           power lines were reported to be blown down in Columbia, 
           MO.

  IMPACT...Hail damage to vehicles is expected. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* Severe thunderstorms will be near...
  Wellsville and Martinsburg around 1100 PM CDT.
  Montgomery City around 1105 PM CDT.
  Buell around 1110 PM CDT.

Other locations in the path of these severe thunderstorms include
Bellflower.

This includes Interstate 70 in Missouri between exits 121 and 183.
 
This also includes Rock Bridge State Park, Jewell Cemetery Historic
Site, and Graham Cave State Park.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3924 9208 3909 9126 3896 9126 3885 9130
      3885 9142 3875 9142 3868 9155 3870 9163
      3871 9173 3870 9174 3891 9248 3893 9250
TIME...MOT...LOC 0354Z 283DEG 49KT 3909 9167 3876 9196 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...70MPH
 
$$

19

1 follow-up statement

087 
WWUS53 KLSX 210409
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
1109 PM CDT Sun Jun 20 2021

MOC019-210418-
/O.CAN.KLSX.SV.W.0087.000000T0000Z-210621T0430Z/
Boone MO-
1109 PM CDT Sun Jun 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN BOONE COUNTY 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 100 AM CDT for
central and east central Missouri.

LAT...LON 3919 9178 3909 9126 3895 9126 3885 9130
      3885 9142 3875 9142 3868 9155 3870 9163
      3871 9173 3870 9174 3882 9215 3883 9215
TIME...MOT...LOC 0408Z 283DEG 49KT 3905 9145 3872 9174 

$$

MOC007-027-139-210430-
/O.CON.KLSX.SV.W.0087.000000T0000Z-210621T0430Z/
Audrain MO-Montgomery MO-Callaway MO-
1109 PM CDT Sun Jun 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1130 PM CDT
FOR SOUTHEASTERN AUDRAIN...MONTGOMERY AND NORTHERN CALLAWAY
COUNTIES...

At 1108 PM CDT, severe thunderstorms were located along a line
extending from Buell to near Chamois, moving east at 55 mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Trained weather spotters.

IMPACT...Hail damage to vehicles is expected. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

These severe storms will be near...
  Bellflower and Buell around 1115 PM CDT.

This also includes Graham Cave State Park.
 
This includes Interstate 70 in Missouri between exits 144 and 183.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3919 9178 3909 9126 3895 9126 3885 9130
      3885 9142 3875 9142 3868 9155 3870 9163
      3871 9173 3870 9174 3882 9215 3883 9215
TIME...MOT...LOC 0408Z 283DEG 49KT 3905 9145 3872 9174 

HAIL...1.00IN
WIND...70MPH
 
$$

19

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 8:41 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Shelby	49 min
Jun 20, 9:07 PM CDT	Tornado Warning	LSX	Marion, Shelby	38 min
Jun 20, 9:17 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Marion, Monroe, Ralls, Shelby	43 min
Jun 20, 9:42 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Monroe	48 min
Jun 20, 9:59 PM CDT	Severe Thunderstorm Warning	LSX	Marion, Monroe, Pike, Ralls	46 min
Jun 20, 10:10 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Monroe, Montgomery, Pike, Ralls	50 min
Jun 20, 10:22 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Callaway	38 min
Jun 20, 10:27 PM CDT	Areal Flood Advisory	LSX	Audrain, Boone, Monroe	3 hr
Jun 20, 10:42 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Cole, Moniteau	48 min
Jun 20, 11:29 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Cole, Franklin, Gasconade, Lincoln and 3 more	31 min
Jun 20, 11:41 PM CDT	Severe Thunderstorm Warning	LSX	Lincoln, Saint Charles	19 min
Jun 20, 11:59 PM CDT	Severe Thunderstorm Warning	LSX	Franklin, Gasconade, Montgomery, Osage, Warren	31 min
Jun 21, 12:34 AM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Cole, Moniteau	26 min

Nearby

Severe Thunderstorm Warnings in Missouri, 2021 Every 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.