Alert archive / Illinois / Flash Flood Warnings in 2025

Flash Flood Warning 19, NWS Chicago, IL

August 17, 2025LaSalle County, Illinois

NWS Chicago, IL issued this flash flood warning at Aug 17, 2025, 7:17 PM CDT for LaSalle County, Illinois. It was in force for 3 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: Aug 17, 2025, 7:17 PM CDT (00:17 UTC)
Expired: Aug 17, 2025, 10:00 PM CDT
In force: 3 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

County LaSalle County, IL

The radar

The Chicago radar (KLOT), 73 km from the middle of the area, began a volume at 00:17 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.

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 Aug 17, 6:36 PM CDT, 41 minutes earlier.

Area forecast discussion, Aug 17, 6:36 PM CDT, 41 minutes before

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Hazardous weather outlook, Aug 17, 3:41 PM CDT, 3 hours 36 minutes before

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<body>
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    <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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      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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In the hours before

Local storm report, Aug 17, 2:01 PM CDT, 5 hours 16 minutes before

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<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.
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Local storm report, Aug 17, 4:53 PM CDT, 2 hours 24 minutes before

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<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>
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Local storm report, Aug 17, 6:41 PM CDT, 36 minutes before

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<head>
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  <title>Service Notice</title>
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</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>
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</html>

Local storm report, Aug 17, 6:58 PM CDT, 19 minutes before

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<head>
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  <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>

Local storm report, Aug 17, 7:03 PM CDT, 14 minutes before

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<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
Aug 18, 1:14 PM CDT	Special Weather Statement	LOT	Winnebago	46 min
Aug 18, 1:45 PM CDT	Special Weather Statement	LOT	Boone	30 min
Aug 18, 2:12 PM CDT	Special Weather Statement	LOT	McHenry	33 min
Aug 18, 2:21 PM CDT	Flood Watch	LOT	Boone, Cook, DeKalb, DuPage, Grundy, Kane and 9 more	13 hr
Aug 18, 2:53 PM CDT	Special Weather Statement	LOT	DeKalb	37 min
Aug 18, 3:17 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb	43 min
Aug 18, 3:39 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Lee, Ogle	51 min
Aug 18, 3:49 PM CDT	Areal Flood Advisory	LOT	DeKalb	3 hr
Aug 18, 4:04 PM CDT	Tornado Warning	LOT	Kane	26 min
Aug 18, 4:09 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Cook, DeKalb, DuPage, Kane	81 min
Aug 18, 4:17 PM CDT	Areal Flood Advisory	LOT	DeKalb, Lee	71 min
Aug 18, 4:21 PM CDT	Areal Flood Advisory	LOT	Kane	3 hr
Aug 18, 4:28 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Kendall	47 min
Aug 18, 4:29 PM CDT	Special Marine Warning	LOT		2 hr
Aug 18, 4:57 PM CDT	Areal Flood Advisory	LOT	Kane	42 min
Aug 18, 5:07 PM CDT	Areal Flood Advisory	LOT	DuPage	32 min
Aug 18, 5:26 PM CDT	Flash Flood Warning	LOT	DeKalb, Lee	3 hr
Aug 18, 5:37 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Will	4 hr
Aug 18, 5:47 PM CDT	Flash Flood Warning	LOT	DuPage	3 hr
Aug 18, 6:00 PM CDT	Severe Thunderstorm Warning	LOT	Ogle	30 min
Aug 18, 6:01 PM CDT	Flash Flood Warning Considerable damage threat	LOT	DeKalb, Lee	3 hr
Aug 18, 6:17 PM CDT	Areal Flood Advisory	LOT	LaSalle	3 hr
Aug 18, 6:25 PM CDT	Special Weather Statement	LOT	Ogle	20 min
Aug 18, 6:30 PM CDT	Areal Flood Advisory	LOT	Cook, Will	3 hr
Aug 18, 6:52 PM CDT	Flash Flood Warning	LOT	Boone, Winnebago	3 hr

Nearby

Flash Flood Warnings in Illinois, 2025 Every flash flood warning in 2025

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; radar from the NEXRAD Level II archive.