Alert archive / Iowa / Dense Fog Advisories in 2021

Dense Fog Advisory 14, NWS La Crosse, WI

December 24, 20216 counties in Iowa; 4 counties in Minnesota

NWS La Crosse, WI issued this dense fog advisory at Dec 24, 2021, 7:47 AM CST for 6 counties in Iowa; 4 counties in Minnesota. It took effect at Dec 24, 2021, 9:00 AM CST. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued: Dec 24, 2021, 7:47 AM CST (13:47 UTC)
In effect from: Dec 24, 2021, 9:00 AM CST
Expired: Dec 24, 2021, 2:00 PM CST
In force: 5 hr
Issued by: NWS La Crosse, WI

Counties Chickasaw County, IA, Fayette County, IA, Floyd County, IA, Howard County, IA, Mitchell County, IA, Winneshiek County, IA, Dodge County, MN, Fillmore County, MN, Mower County, MN, Olmsted County, MN

The radar

The La Crosse radar (KARX), 106 km from the middle of the area, began a volume at 13:46 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

Minneapolis, MN (KMPX), launched 12:00Z, 1.8 hours before the alert went out and 184 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2004 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 483 m²/s²
0-3 km storm-relative helicity: 524 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 dense fog advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS La Crosse, WI wrote its last area forecast discussion before this dense fog advisory went out at Dec 23, 5:48 PM CST, 13 hours 59 minutes earlier.

Area forecast discussion, Dec 23, 5:48 PM CST, 13 hours 59 minutes before

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Hazardous weather outlook, Dec 23, 12:17 PM CST, 19 hours 30 minutes before

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        The site you requested is temporarily down for maintenance or an unexpected outage.
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The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 24, 2:40 PM CST	Dense Fog Advisory	ARX	Adams, Buffalo, Clark, Crawford, Grant, Jackson and 7 more	9 hr

Nearby

Dense Fog Advisories in Iowa, 2021 Dense Fog Advisories in Minnesota, 2021 Every dense fog 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.