Alert archive / Illinois / Areal Flood Advisories in 2021

Areal Flood Advisory 41, NWS St. Louis, MO

July 11, 2021Randolph County, Saint Clair County, Washington County, Illinois

NWS St. Louis, MO issued this areal flood advisory at Jul 11, 2021, 7:50 AM CDT for Randolph County, Saint Clair County, Washington County, Illinois. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued: Jul 11, 2021, 7:50 AM CDT (12:50 UTC)
Expired: Jul 11, 2021, 11:00 AM CDT
In force: 3 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon

Counties Randolph County, IL, Saint Clair County, IL, Washington County, IL

The radar

The St Louis radar (KLSX), 95 km from the middle of the area, began a volume at 12:52 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, 0.8 hours before the alert went out and 228 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: 307 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 520 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: -10 m²/s²
0-3 km storm-relative helicity: 23 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

What forecasters said that day

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

NWS St. Louis, MO wrote its last area forecast discussion before this areal flood advisory went out at Jul 11, 6:38 AM CDT, 1 hour 12 minutes earlier.

Area forecast discussion, Jul 11, 6:38 AM CDT, 1 hour 12 minutes before

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Hazardous weather outlook, Jul 11, 3:30 AM CDT, 4 hours 20 minutes before

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</head>
<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>
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        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
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        Please try again in a few minutes.
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The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 10, 8:48 PM CDT	Areal Flood Advisory	LSX	Crawford, Iron, Madison, Reynolds, Saint Francois, Washington	6 hr
Jul 11, 8:25 AM CDT	River Flood Warning	LSX	Lewis	60 hr
Jul 11, 8:25 AM CDT	River Flood Warning	LSX	Marion	22 hr
Jul 11, 9:46 AM CDT	Areal Flood Advisory	LSX	Lewis	3 hr
Jul 11, 6:04 PM CDT	Areal Flood Advisory	LSX	Saint Charles, Saint Louis	3 hr
Jul 11, 6:23 PM CDT	Areal Flood Advisory	LSX	Sainte Genevieve	3 hr

Nearby

Areal Flood Advisories in Illinois, 2021 Every areal flood advisory 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.