Alert archive / Illinois / Special Weather Statements in 2021

Special Weather Statement, NWS Chicago, IL

August 12, 2021Livingston County, Illinois

NWS Chicago, IL issued this special weather statement at Aug 12, 2021, 12:09 PM CDT for Livingston County, Illinois. It was in force for 51 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: Aug 12, 2021, 12:09 PM CDT (17:09 UTC)
Expired: Aug 12, 2021, 1:00 PM CDT
In force: 51 min
Issued by: NWS Chicago, IL
Hail: 0.75 in
Wind: 30

County Livingston County, IL

The radar

The Chicago radar (KLOT), 87 km from the middle of the area, began a volume at 17:10 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

Lincoln, IL (KILX), launched 12:00Z, 5.2 hours before the alert went out and 93 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: 1191 J/kg
Mixed-layer CIN: -177 J/kg
Mixed-layer LCL: 1149 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 140 m²/s²
0-3 km storm-relative helicity: 128 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.1

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this special weather statement went out at Aug 12, 11:48 AM CDT, 21 minutes earlier.

Area forecast discussion, Aug 12, 11:48 AM CDT, 21 minutes before

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Hazardous weather outlook, Aug 12, 4:42 AM CDT, 7 hours 27 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
442 AM CDT Thu Aug 12 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-130945-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
442 AM CDT Thu Aug 12 2021 /542 AM EDT Thu Aug 12 2021/

This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.

.DAY ONE...Today and Tonight.

Weather hazards expected...

  Elevated Thunderstorm Risk...with an associated:
     Limited hail risk...up to quarter size here.
     Limited damaging wind risk...up to 65 mph.
  Limited Flooding Risk.
  Elevated Excessive Heat Risk.

DISCUSSION...

Scattered thunderstorms may produce isolated damaging wind gusts
south of the Interstate 80 corridor early this morning, along with
locally heavy rainfall and possibly some flooding. Additional
scattered thunderstorms are possible late this afternoon into
tonight across the entire area. Some of these storms may be
severe, with damaging wind gusts the main threat, with the severe
threat decreasing late evening into the overnight.

Warm and humid conditions will persist today, though peak
afternoon heat indices should top out just under 105 degrees.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Limited Thunderstorm Risk.
Tuesday and Wednesday...
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotters may be needed late this afternoon and this evening.

GENERAL STORM MOTION OF THE DAY:

  Moving toward east at 35 mph early this morning, and to the
  southeast at 35 mph later today and tonight.

LMZ740>745-130945-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
442 AM CDT Thu Aug 12 2021

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Today and Tonight.

Weather hazards expected...

  Elevated Thunderstorm Risk...with an associated:
     Limited Waterspout Risk.
     Limited hail risk...up to quarter size.
     Limited thunderstorm wind gust risk...up to 55 knots.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Limited Thunderstorm Risk.
Wednesday...
  Limited Thunderstorm Risk.

Ratzer

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In the hours before

Local storm report, Aug 12, 9:26 AM CDT, 2 hours 43 minutes before

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Special weather statement, Aug 12, 9:30 AM CDT, 2 hours 39 minutes before

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Local storm report, Aug 12, 10:49 AM CDT, 1 hour 20 minutes before

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Local storm report, Aug 12, 11:01 AM CDT, 1 hour 8 minutes before

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Local storm report, Aug 12, 11:58 AM CDT, 11 minutes before

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Special weather statement, Aug 12, 12:09 PM CDT, 0 minutes before

Special Weather Statement
National Weather Service Chicago/Romeoville
1209 PM CDT Thu Aug 12 2021

ILZ019-032-121800-
Livingston IL-La Salle IL-
1209 PM CDT Thu Aug 12 2021

...Strong thunderstorms will impact portions of northern Livingston
and southern La Salle Counties through 100 PM CDT...

At 1209 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Wenona to Cornell to near Pontiac.
Movement was east at 30 mph.

HAZARD...Winds in excess of 30 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Streator, Pontiac, Dwight, Wenona, Odell, South Streator, Cornell,
Saunemin, Ransom, Kangley, Long Point, Dana and Emington.

Including the following interstates...
 I-39 near mile marker 41.
 I-55 between mile markers 193 and 216.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4077 8865 4093 8880 4093 8893 4104 8905
      4110 8905 4111 8916 4117 8866 4111 8858
      4111 8848 4097 8829 4076 8837
TIME...MOT...LOC 1709Z 273DEG 27KT 4107 8899 4099 8874 4085 8861

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

Carlaw

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 11, 8:57 PM CDT	Severe Thunderstorm Warning	LOT	DuPage, Kane	48 min
Aug 11, 9:43 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	26 min
Aug 12, 12:45 AM CDT	Special Weather Statement	LOT	Kendall	45 min
Aug 12, 1:31 AM CDT	Special Weather Statement	LOT	Livingston	44 min
Aug 12, 2:13 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Kankakee, Livingston	47 min
Aug 12, 2:22 AM CDT	Special Weather Statement	LOT	Will	38 min
Aug 12, 2:27 AM CDT	Special Weather Statement	LOT	Will	33 min
Aug 12, 2:30 AM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	29 min
Aug 12, 2:46 AM CDT	Special Marine Warning	LOT		89 min
Aug 12, 2:50 AM CDT	Special Weather Statement	LOT	LaSalle	40 min
Aug 12, 2:55 AM CDT	Severe Thunderstorm Warning	LOT	Cook	50 min
Aug 12, 3:02 AM CDT	Severe Thunderstorm Warning	LOT	LaSalle	43 min
Aug 12, 3:16 AM CDT	Special Weather Statement	LOT	Grundy, Kendall, Will	44 min
Aug 12, 3:43 AM CDT	Special Weather Statement	LOT	DuPage, Kane, Kendall, Will	47 min
Aug 12, 3:51 AM CDT	Special Weather Statement	LOT	Ford, Iroquois	39 min
Aug 12, 4:59 AM CDT	Special Weather Statement	LOT	Livingston	31 min
Aug 12, 8:01 AM CDT	Special Weather Statement	LOT	Ford	29 min
Aug 12, 8:22 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	68 min
Aug 12, 9:27 AM CDT	Areal Flood Advisory	LOT	Ford	2 hr
Aug 12, 9:30 AM CDT	Special Weather Statement	LOT	Ford	45 min
Aug 12, 9:59 AM CDT	Flash Flood Warning	LOT	Ford	5 hr
Aug 12, 12:01 PM CDT	Areal Flood Advisory	LOT	Ford	4 hr
Aug 12, 1:09 PM CDT	Special Weather Statement	LOT	Iroquois	51 min
Aug 12, 2:44 PM CDT	Small Craft Advisory	LOT		7 hr
Aug 12, 2:59 PM CDT	Areal Flood Warning	LOT	Ford	19 hr
Aug 12, 2:43 AM CDT	Special Weather Statement	LOT	Lake	47 min
Aug 12, 2:51 AM CDT	Special Weather Statement	LOT	Jasper, Lake, Newton, Porter	54 min
Aug 12, 4:20 AM CDT	Special Weather Statement	LOT	Benton, Newton	40 min
Aug 12, 4:30 AM CDT	Severe Thunderstorm Warning	LOT	Jasper, Newton	45 min

Nearby

Special Weather Statements in Illinois, 2021 Every 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.