Alert archive / Illinois / Special Weather Statements in 2021

Special Weather Statement, NWS Chicago, IL

August 29, 2021Kane County, Lake County, Illinois

NWS Chicago, IL issued this special weather statement at Aug 29, 2021, 2:20 PM CDT for Kane County, Lake County, Illinois. It was in force for 40 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 29, 2021, 2:20 PM CDT (19:20 UTC)
Expired: Aug 29, 2021, 3:00 PM CDT
In force: 40 min
Issued by: NWS Chicago, IL
Hail: 0.00 in
Wind: 50

Counties Kane County, IL, Lake County, IL

The radar

The Chicago radar (KLOT), 64 km from the middle of the area, began a volume at 19:21 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, 7.3 hours before the alert went out and 231 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: 810 J/kg
Mixed-layer CIN: -63 J/kg
Mixed-layer LCL: 1215 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 91 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

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 29, 1:20 PM CDT, 1 hour earlier.

Area forecast discussion, Aug 29, 1:20 PM CDT, 1 hour before

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  <meta name="viewport" content="width=device-width, initial-scale=1">
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  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
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      <p id="message2">
        Please try again in a few minutes.
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        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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Hazardous weather outlook, Aug 29, 12:18 PM CDT, 2 hours 2 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
1218 PM CDT Sun Aug 29 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-301730-
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-
1218 PM CDT Sun Aug 29 2021 /118 PM EDT Sun Aug 29 2021/

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

.DAY ONE...This Afternoon and Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk...with an associated:
     Limited damaging wind risk...up to 60 mph.
  Limited Excessive Heat Risk.

DISCUSSION...

Scattered thunderstorms are expected this afternoon into this
evening. Some of these thunderstorms may become severe with
damaging wind gusts the main severe weather threat. Heavy rain
will also be possible, which may cause localized flooding.

The storm coverage will increase in the Chicago area after 2 to
3 pm CDT, with highest coverage mid afternoon through early evening.

Heat index readings will reach near 100 degrees today.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Monday...
  Limited Thunderstorm Risk.
Tuesday...
  Limited Thunderstorm Risk.
  High Swim Risk.
Wednesday...
  High Swim Risk.
Friday and Saturday...
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed this afternoon into this evening.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east northeast at around 20 mph.

LMZ740>745-301730-
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-
1218 PM CDT Sun Aug 29 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...This Afternoon and Tonight.

Weather hazards expected...

  Hazardous conditions for small craft.
  Limited Thunderstorm Risk...with an associated:
     Limited thunderstorm wind gust risk...up to 50 knots.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Friday and Saturday...
  Limited Thunderstorm Risk.

KMD

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In the hours before

Special weather statement, Aug 29, 1:05 PM CDT, 1 hour 15 minutes before

Special Weather Statement
National Weather Service Chicago/Romeoville
105 PM CDT Sun Aug 29 2021

ILZ005-006-291845-
Lake IL-McHenry IL-
105 PM CDT Sun Aug 29 2021

...Strong thunderstorms will impact portions of northwestern Lake and
McHenry Counties through 145 PM CDT...

At 105 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Silver Lake to Wonder Lake to near
Marengo. Movement was east at 35 mph.

HAZARD...Winds of 45 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Crystal Lake, Lake in the Hills, Round Lake Beach, McHenry,
Woodstock, Huntley, Round Lake, Antioch, Fox Lake, Lake Villa, Island
Lake, Marengo, Lindenhurst, Johnsburg, Lakemoor, Spring Grove, Wonder
Lake, Wadsworth, Lakewood and Long Lake.

This includes...  Chain O Lakes State Park, Mchenry County College,
Mchenry County Fairgrounds, and Moraine Hills State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4249 8794 4220 8833 4221 8870 4233 8869
      4250 8843
TIME...MOT...LOC 1805Z 255DEG 30KT 4258 8816 4239 8836 4227 8854

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Birk

Special weather statement, Aug 29, 1:40 PM CDT, 40 minutes before

Special Weather Statement
National Weather Service Chicago/Romeoville
140 PM CDT Sun Aug 29 2021

ILZ005-006-291915-
Lake IL-McHenry IL-
140 PM CDT Sun Aug 29 2021

...Strong thunderstorms will impact portions of Lake and southeastern
McHenry Counties through 215 PM CDT...

At 140 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from Winthrop Harbor to Gages Lake to Lake in the
Hills. Movement was east at 40 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Waukegan, Buffalo Grove, Crystal Lake, North Chicago, Gurnee,
Mundelein, Algonquin, Highland Park, Lake in the Hills, Round Lake
Beach, McHenry, Vernon Hills, Zion, Huntley, Grayslake, Libertyville,
Lake Zurich, Lake Forest, Round Lake and Antioch.

Including the following interstates...
 I-94 between mile markers 1 and 24.
 I-294 between mile markers 1 and 24.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4249 8780 4238 8781 4236 8782 4237 8782
      4233 8783 4233 8782 4231 8782 4230 8783
      4229 8783 4221 8780 4216 8776 4216 8849
      4237 8821 4250 8819
TIME...MOT...LOC 1840Z 266DEG 33KT 4250 8783 4233 8800 4219 8834

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Birk

Special weather statement, Aug 29, 2:20 PM CDT, 0 minutes before

Special Weather Statement
National Weather Service Chicago/Romeoville
220 PM CDT Sun Aug 29 2021

ILZ005-006-011>013-103-292000-
Lake IL-Kane IL-De Kalb IL-McHenry IL-DuPage IL-Northern Cook IL-
220 PM CDT Sun Aug 29 2021

...Strong thunderstorms will impact portions of southern Lake, east
central De Kalb, northern Kane, southeastern McHenry, northwestern
DuPage and northwestern Cook Counties through 300 PM CDT...

At 219 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from Lincolnshire to Barrington Hills to near Maple
Park. Movement was east at 25 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Elgin, Waukegan, Arlington Heights, Schaumburg, Palatine, Mount
Prospect, Hoffman Estates, Glenview, DeKalb, Buffalo Grove, Bartlett,
Streamwood, Hanover Park, Carpentersville, Wheeling, Northbrook, Elk
Grove Village, St. Charles, North Chicago and Mundelein.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4231 8782 4230 8783 4227 8783 4219 8779
      4213 8775 4207 8793 4191 8829 4195 8875
      4234 8804
TIME...MOT...LOC 1919Z 276DEG 19KT 4220 8792 4213 8821 4198 8858

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Birk

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 28, 8:11 PM CDT	Small Craft Advisory	LOT		20 hr
Aug 29, 1:05 PM CDT	Special Weather Statement	LOT	McHenry	40 min
Aug 29, 1:40 PM CDT	Special Weather Statement	LOT	Lake	35 min
Aug 29, 3:02 PM CDT	Special Weather Statement	LOT	Lake	43 min
Aug 29, 3:10 PM CDT	Special Marine Warning	LOT		95 min
Aug 29, 4:23 PM CDT	Special Weather Statement	LOT	Cook	22 min
Aug 29, 4:29 PM CDT	Special Weather Statement	LOT	Will	31 min
Aug 29, 4:52 PM CDT	Special Weather Statement	LOT	Will	23 min
Aug 29, 5:50 PM CDT	Special Weather Statement	LOT	Kankakee	40 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.