Alert archive / Illinois / Flash Flood Warnings in 2023

Flash Flood Warning 5, NWS Chicago, IL

July 2, 2023Cook County, DuPage County, Will County, Illinois

NWS Chicago, IL issued this flash flood warning at Jul 2, 2023, 9:16 AM CDT for Cook County, DuPage County, Will County, Illinois. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 2, 2023, 9:16 AM CDT (14:16 UTC)
Expired: Jul 2, 2023, 1:15 PM CDT
In force: 4 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties Cook County, IL, DuPage County, IL, Will County, IL

The radar

The Chicago radar (KLOT), 21 km from the middle of the area, began a volume at 14:19 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, 2.3 hours before the alert went out and 185 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: 275 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 643 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning 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 flash flood warning went out at Jul 2, 6:25 AM CDT, 2 hours 51 minutes earlier.

Area forecast discussion, Jul 2, 6:25 AM CDT, 2 hours 51 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <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.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Hazardous weather outlook, Jul 2, 4:21 AM CDT, 4 hours 55 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <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.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 1, 8:01 PM CDT	Special Weather Statement	LOT	Grundy	29 min
Jul 2, 6:55 AM CDT	Areal Flood Advisory	LOT	Cook, DeKalb, DuPage, Kane	4 hr
Jul 2, 10:15 AM CDT	Flash Flood Warning Considerable damage threat	LOT	Cook	4 hr
Jul 2, 2:38 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Lake	3 hr
Jul 2, 2:38 PM CDT	Flash Flood Warning	LOT	Cook	4 hr
Jul 2, 3:06 PM CDT	Beach Hazards Statement	LOT	Cook, Lake	6 hr
Jul 2, 3:08 PM CDT	Small Craft Advisory	LOT		6 hr
Jul 2, 4:02 PM CDT	River Flood Warning	LOT	Cook	13 hr
Jul 2, 4:31 PM CDT	Areal Flood Advisory	LOT	Cook	119 min
Jul 2, 6:25 PM CDT	Areal Flood Warning	LOT	Cook	7 hr

Nearby

Flash Flood Warnings in Illinois, 2023 Every flash flood warning in 2023

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.