Alert archive / Missouri / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 165, NWS St. Louis, MO

September 20, 2021Knox County, Lewis County, Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Sep 20, 2021, 8:45 PM CDT for Knox County, Lewis County, Missouri. It was in force for 45 min. 1 report 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: Sep 20, 2021, 8:45 PM CDT (01:45 UTC)
Expired: Sep 20, 2021, 9:30 PM CDT
In force: 45 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Knox County, MO, Lewis County, MO

The radar

The St Louis radar (KLSX), 183 km from the middle of the area, began a volume at 01:46 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
Sep 20, 9:27 PM CDT	TSTM WND DMG	Canton, MO	12 TO 18 INCH TREE AND A FEW POWER POLES DOWN IN CANTON.

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

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.8 hours before the alert went out and 188 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: 1090 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 1240 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 139 m²/s²
0-3 km storm-relative helicity: 217 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.7

Open this sounding in Storm Lab

The text

As transmitted.

141 
WUUS53 KLSX 210145
SVRLSX
MOC103-111-210230-
/O.NEW.KLSX.SV.W.0165.210921T0145Z-210921T0230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
845 PM CDT Mon Sep 20 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Southeastern Knox County in northeastern Missouri...
  Lewis County in northeastern Missouri...

* Until 930 PM CDT.

* At 845 PM CDT, a severe thunderstorm was located near La Belle,
  moving northeast at 30 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.

* This severe thunderstorm will be near...
  La Belle around 855 PM CDT.
  Lewistown around 900 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4025 9154 4025 9150 4024 9151 4020 9150
      4018 9151 4012 9151 4008 9150 3995 9198
      4009 9212 4026 9186
TIME...MOT...LOC 0145Z 237DEG 25KT 4007 9198 

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

$$

Britt

3 follow-up statements

328 
WWUS53 KLSX 210200
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
900 PM CDT Mon Sep 20 2021

MOC103-210210-
/O.CAN.KLSX.SV.W.0165.000000T0000Z-210921T0230Z/
Knox MO-
900 PM CDT Mon Sep 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN KNOX COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4025 9154 4025 9150 4024 9151 4020 9150
      4018 9151 4012 9151 4002 9195 4018 9195
      4026 9186
TIME...MOT...LOC 0200Z 237DEG 25KT 4013 9187 

$$

MOC111-210230-
/O.CON.KLSX.SV.W.0165.000000T0000Z-210921T0230Z/
Lewis MO-
900 PM CDT Mon Sep 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 930 PM CDT
FOR NORTHERN LEWIS COUNTY...

At 900 PM CDT, a severe thunderstorm was located over La Belle,
moving northeast at 30 mph.

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

SOURCE...Radar indicated.

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

This severe thunderstorm will remain over mainly rural areas of
northern Lewis County, including the following locations...
Monticello.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4025 9154 4025 9150 4024 9151 4020 9150
      4018 9151 4012 9151 4002 9195 4018 9195
      4026 9186
TIME...MOT...LOC 0200Z 237DEG 25KT 4013 9187 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Britt

637 
WWUS53 KLSX 210214
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
914 PM CDT Mon Sep 20 2021

MOC111-210230-
/O.CON.KLSX.SV.W.0165.000000T0000Z-210921T0230Z/
Lewis MO-
914 PM CDT Mon Sep 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 930 PM CDT
FOR NORTHERN LEWIS COUNTY...

At 914 PM CDT, a severe thunderstorm was located near Lewistown,
moving northeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Canton, Lewistown and Monticello. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4025 9154 4025 9150 4024 9151 4020 9150
      4018 9151 4012 9151 4004 9188 4015 9188
      4026 9183
TIME...MOT...LOC 0214Z 246DEG 25KT 4016 9174 

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

$$

Britt

865 
WWUS53 KLSX 210224
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
924 PM CDT Mon Sep 20 2021

MOC111-210234-
/O.EXP.KLSX.SV.W.0165.000000T0000Z-210921T0230Z/
Lewis MO-
924 PM CDT Mon Sep 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN LEWIS COUNTY WILL
EXPIRE AT 930 PM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds are still possible with this thunderstorm.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
St Louis.

LAT...LON 4025 9154 4025 9150 4024 9151 4020 9150
      4018 9151 4012 9151 4004 9188 4015 9188
      4026 9183
TIME...MOT...LOC 0224Z 237DEG 25KT 4020 9166 

$$

Britt

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 20, 9:56 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Monroe, Ralls	51 min
Sep 20, 10:35 PM CDT	Severe Thunderstorm Warning	LSX	Marion, Pike, Ralls	40 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.