Alert archive / Alabama / Dense Fog Advisories in 2021

Dense Fog Advisory 2, NWS Huntsville, AL

March 17, 20214 counties in Alabama

NWS Huntsville, AL issued this dense fog advisory at Mar 17, 2021, 1:24 AM CDT for 4 counties in Alabama. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued: Mar 17, 2021, 1:24 AM CDT (06:24 UTC)
Expired: Mar 17, 2021, 8:18 AM CDT
In force: 7 hr
Issued by: NWS Huntsville, AL

Counties Cullman County, AL, DeKalb County, AL, Jackson County, AL, Marshall County, AL

The radar

The Northeast Alabama radar (KHTX), 57 km from the middle of the area, began a volume at 06:27 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

Birmingham, AL (KBMX), launched 00:00Z, 6.4 hours before the alert went out and 148 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: 221 J/kg
Mixed-layer CIN: -36 J/kg
Mixed-layer LCL: 578 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: -39 m²/s²
0-3 km storm-relative helicity: 20 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.5

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 Huntsville, AL wrote its last area forecast discussion before this dense fog advisory went out at Mar 17, 12:00 AM CDT, 1 hour 24 minutes earlier.

Area forecast discussion, Mar 17, 12:00 AM CDT, 1 hour 24 minutes before

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Hazardous weather outlook, Mar 16, 10:45 PM CDT, 2 hours 39 minutes before

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The office that day

Everything else NWS Huntsville, AL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 17, 7:25 AM CDT	Special Weather Statement	HUN	Morgan	50 min
Mar 17, 7:57 AM CDT	Special Weather Statement	HUN	Madison	48 min
Mar 17, 7:59 AM CDT	Special Weather Statement	HUN	Colbert	46 min
Mar 17, 9:52 AM CDT	Special Weather Statement	HUN	Jackson	23 min
Mar 17, 3:40 PM CDT	Tornado Warning	HUN	Colbert, Franklin	35 min
Mar 17, 4:07 PM CDT	Severe Thunderstorm Warning	HUN	Colbert, Franklin, Lauderdale	26 min
Mar 17, 4:17 PM CDT	Flash Flood Watch	HUN	Colbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more	8 hr
Mar 17, 4:44 PM CDT	Flash Flood Warning	HUN	Cullman, Morgan	5 hr
Mar 17, 5:24 PM CDT	Areal Flood Warning	HUN	Colbert, Franklin, Lauderdale	9 hr
Mar 17, 5:49 PM CDT	Areal Flood Warning	HUN	Cullman	8 hr
Mar 17, 6:05 PM CDT	Severe Thunderstorm Warning	HUN	Marshall	22 min
Mar 17, 6:44 PM CDT	Tornado Warning	HUN	Cullman	31 min

Nearby

Dense Fog Advisories in Alabama, 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.