Alert archive / Missouri / Areal Flood Advisories in 2021

Areal Flood Advisory 1, NWS St. Louis, MO

March 11, 20215 counties in Missouri; Randolph County, Illinois

NWS St. Louis, MO issued this areal flood advisory at Mar 11, 2021, 3:38 PM CST for 5 counties in Missouri; Randolph County, Illinois. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued: Mar 11, 2021, 3:38 PM CST (21:38 UTC)
Expired: Mar 11, 2021, 6:30 PM CST
In force: 3 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon

Counties Randolph County, IL, Crawford County, MO, Iron County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 93 km from the middle of the area, began a volume at 21:37 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, 9.6 hours before the alert went out and 305 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: 2 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 500 m above ground
0-6 km bulk shear: 69 kt
0-1 km storm-relative helicity: 114 m²/s²
0-3 km storm-relative helicity: 198 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 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 Mar 11, 2:30 PM CST, 1 hour 8 minutes earlier.

Area forecast discussion, Mar 11, 2:30 PM CST, 1 hour 8 minutes before

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Hazardous weather outlook, Mar 11, 2:47 PM CST, 51 minutes before

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In the hours before

Local storm report, Mar 11, 1:05 PM CST, 2 hours 33 minutes before

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Local storm report, Mar 11, 2:46 PM CST, 52 minutes before

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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
Mar 11, 3:27 AM CST	Flood Watch	LSX	Boone, Callaway, Cole, Crawford, Franklin, Gasconade and 14 more	55 hr
Mar 11, 12:43 PM CST	Severe Thunderstorm Warning	LSX	Iron, Madison, Sainte Genevieve, Saint Francois	22 min
Mar 11, 1:58 PM CST	Severe Thunderstorm Warning	LSX	Iron, Madison, Sainte Genevieve, Saint Francois	47 min

Nearby

Areal Flood Advisories in Missouri, 2021 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.