Alert archive / Missouri / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 89, NWS St. Louis, MO

June 20, 2021Lincoln County, Saint Charles County, Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Jun 20, 2021, 11:41 PM CDT for Lincoln County, Saint Charles County, Missouri. It was in force for 19 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: Jun 20, 2021, 11:41 PM CDT (04:41 UTC)
Expired: Jun 21, 2021, 12:00 AM CDT
In force: 19 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Lincoln County, MO, Saint Charles County, MO

The radar

The St Louis radar (KLSX), 20 km from the middle of the area, began a volume at 04:40 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.

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

Lincoln, IL (KILX), launched 00:00Z, 4.7 hours before the alert went out and 230 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: 1632 J/kg
Mixed-layer CIN: -62 J/kg
Mixed-layer LCL: 1351 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 159 m²/s²
0-3 km storm-relative helicity: 421 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 13.7

Open this sounding in Storm Lab

The text

As transmitted.

393 
WUUS53 KLSX 210441
SVRLSX
MOC113-183-210500-
/O.NEW.KLSX.SV.W.0089.210621T0441Z-210621T0500Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
1141 PM CDT Sun Jun 20 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Northwestern St. Charles County in east central Missouri...
  Southeastern Lincoln County in east central Missouri...

* Until midnight CDT.

* At 1141 PM CDT, severe thunderstorms were located along a line
  extending from near Moscow Mills to near Innsbrook, moving east at
  55 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Severe thunderstorms will be near...
  Fountain N' Lakes and Chain of Rocks around 1145 PM CDT.
  Wentzville, Lake St. Louis, St. Paul, New Melle and Josephville 
  around 1150 PM CDT.
  O'Fallon and Dardenne Prairie around 1155 PM CDT.
  St. Peters, Weldon Spring and Cottleville around 1200 AM CDT.

This includes Interstate 70 in Missouri between exits 203 and 220.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3895 9067 3893 9066 3891 9064 3889 9063
      3887 9058 3873 9067 3863 9096 3900 9095
TIME...MOT...LOC 0441Z 284DEG 49KT 3892 9091 3871 9103 

HAIL...<.75IN
WIND...60MPH
 
$$

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, 10:55 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Callaway, Montgomery	35 min
Jun 20, 11:29 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Cole, Franklin, Gasconade, Lincoln and 3 more	31 min
Jun 20, 11:59 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.