Alert archive / Illinois / Special Weather Statements in 2021

Special Weather Statement, NWS Quad Cities, IA

June 18, 2021Stephenson County, Illinois

NWS Quad Cities, IA issued this special weather statement at Jun 18, 2021, 2:21 AM CDT for Stephenson County, Illinois. It was in force for 24 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 18, 2021, 2:21 AM CDT (07:21 UTC)
Expired
Jun 18, 2021, 2:45 AM CDT
In force
24 min
Issued by
NWS Quad Cities, IA

County Stephenson County, IL

The radar

The Milwaukee radar (KMKX), 107 km from the middle of the area, began a volume at 07:22 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 nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 7.4 hours before the alert went out and 113 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, Davenport, at 00:00Z on 2021-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1531 joules per kilogram.LCLLFCEL10008507005003002001001 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, Davenport, at 00:00Z on 2021-06-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 48 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
1531 J/kg
Mixed-layer CIN
-220 J/kg
Mixed-layer LCL
1979 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
48 m²/s²
0-3 km storm-relative helicity
169 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

475 
WWUS83 KDVN 180721
SPSDVN

Special Weather Statement
National Weather Service Quad Cities IA/IL
221 AM CDT Fri Jun 18 2021

ILC177-180745-
Stephenson-
221 AM CDT Fri Jun 18 2021

...A STRONG THUNDERSTORM WILL AFFECT STEPHENSON COUNTY UNTIL 245 AM
CDT...

At 221 AM CDT, a strong thunderstorm was located near Cedarville, or
8 miles northwest of Freeport, moving east at 60 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
Freeport, Lena, Pearl City, Cedarville, Davis, Dakota, German Valley,
Winslow, Rock City, Ridott, Buena Vista, Rock Grove, Oneco,
Orangeville, Eleroy, Damascus, Lake Le-Aqua-
na State Park, Mc Connell, Scioto Mills and Winneshiek.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4250 8940 4220 8940 4220 8991 4251 8985
TIME...MOT...LOC 0721Z 277DEG 52KT 4240 8969 

$$

Ervin

The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 18, 4:01 AM CDTSpecial Weather StatementDVNDubuque44 min
Jun 18, 9:39 AM CDTSpecial Weather StatementDVNLee36 min
Jun 18, 9:59 AM CDTSpecial Weather StatementDVNLee31 min
Jun 18, 4:17 AM CDTSpecial Weather StatementDVNHenry, Rock Island43 min
Jun 18, 4:51 AM CDTSpecial Weather StatementDVNRock Island39 min

Nearby

Special Weather Statements in Illinois, 2021Every special weather statement 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.