Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 50, NWS St. Louis, MO

May 27, 2021Greene County, Macoupin County, Montgomery County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at May 27, 2021, 12:07 PM CDT for Greene County, Macoupin County, Montgomery County, Illinois. It was in force for 38 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
May 27, 2021, 12:07 PM CDT (17:07 UTC)
Expired
May 27, 2021, 12:45 PM CDT
In force
38 min
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Tornado
Possible
Hail
0.88 in
Wind
70.0 mph

Counties Greene County, IL, Macoupin County, IL, Montgomery County, IL

The radar

The Lincoln radar (KILX), 92 km from the middle of the area, began a volume at 17:06 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.

IssuedProductOfficeLasted
May 27, 11:26 AM CDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 5.1 hours before the alert went out and 136 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 12:00Z on 2021-05-27Temperature 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 12:00Z on 2021-05-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 130 square meters per square second.19395878Sfc1 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
1679 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
130 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

205 
WUUS53 KLSX 271707
SVRLSX
ILC061-117-135-271745-
/O.NEW.KLSX.SV.W.0050.210527T1707Z-210527T1745Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
1207 PM CDT Thu May 27 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Northeastern Greene County in southwestern Illinois...
  Northern Macoupin County in southwestern Illinois...
  Northwestern Montgomery County in south central Illinois...

* Until 1245 PM CDT.

* At 1206 PM CDT, severe thunderstorms were located along a line
  extending from 6 miles south of Franklin to near Palmyra, moving
  east at 40 mph.

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

  SOURCE...Radar indicated.

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

* Severe thunderstorms will be near...
  Palmyra around 1210 PM CDT.

Other locations in the path of these severe thunderstorms include
Virden and White Oak.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3937 9017 3952 9018 3952 8953 3951 8953
TIME...MOT...LOC 1706Z 259DEG 35KT 3953 9005 3940 9004 

TORNADO...POSSIBLE
HAIL...0.88IN
WIND...70MPH
 
$$

MRM
1 follow-up statement
002 
WWUS53 KLSX 271719
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
1219 PM CDT Thu May 27 2021

ILC061-271728-
/O.CAN.KLSX.SV.W.0050.000000T0000Z-210527T1745Z/
Greene IL-
1219 PM CDT Thu May 27 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN GREENE 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 700 PM CDT for
south central and southwestern Illinois.

LAT...LON 3940 9002 3952 9003 3952 8953 3951 8953
TIME...MOT...LOC 1718Z 260DEG 37KT 3955 8988 3942 8987 

$$

ILC117-135-271745-
/O.CON.KLSX.SV.W.0050.000000T0000Z-210527T1745Z/
Macoupin IL-Montgomery IL-
1219 PM CDT Thu May 27 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1245 PM CDT
FOR NORTHEASTERN MACOUPIN AND NORTHWESTERN MONTGOMERY COUNTIES...

At 1218 PM CDT, severe thunderstorms were located along a line
extending from near Waverly to near Girard, moving east at 40 mph.

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

SOURCE...Radar indicated.

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

These severe storms will be near...
  Virden around 1225 PM CDT.

Other locations in the path of these severe thunderstorms include
White Oak.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3940 9002 3952 9003 3952 8953 3951 8953
TIME...MOT...LOC 1718Z 260DEG 37KT 3955 8988 3942 8987 

TORNADO...POSSIBLE
HAIL...0.88IN
WIND...70MPH
 
$$

MRM

The office that day

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

IssuedProductOfficeCountiesLasted
May 27, 11:13 AM CDTSevere Thunderstorm WarningLSXCalhoun, Greene, Jersey47 min
May 27, 11:32 AM CDTSevere Thunderstorm WarningLSXGreene, Macoupin43 min
May 27, 11:50 AM CDTSevere Thunderstorm WarningLSXCalhoun, Greene, Jersey, Macoupin, Madison, Saint Clair55 min
May 27, 12:26 PM CDTTornado WarningLSXMacoupin, Madison34 min
May 27, 12:39 PM CDTAreal Flood AdvisoryLSXCalhoun, Madison3 hr
May 27, 12:56 PM CDTTornado WarningLSXBond, Macoupin, Madison, Montgomery28 min
May 27, 2:16 PM CDTAreal Flood AdvisoryLSXBond, Fayette3 hr
May 27, 2:31 PM CDTSevere Thunderstorm WarningLSXClinton, Fayette, Marion44 min
May 27, 2:46 PM CDTSevere Thunderstorm WarningLSXMonroe, Randolph29 min

Nearby

Severe Thunderstorm Warnings in Illinois, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.