Alert archive / Colorado / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 216, NWS Denver/Boulder, CO

August 17, 2020Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 17, 2020, 1:55 AM MDT for Weld County, Colorado. It was in force for 35 min. 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, 2020, 1:55 AM MDT (07:55 UTC)
Expired: Aug 17, 2020, 2:30 AM MDT
In force: 35 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

County Weld County, CO

The radar

The Cheyenne radar (KCYS), 75 km from the middle of the area, began a volume at 07:58 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

Denver, CO (KDNR), launched 00:00Z, 7.9 hours before the alert went out and 125 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: 3 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 3874 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -23 m²/s²
0-3 km storm-relative helicity: 11 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 severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Denver/Boulder, CO wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 16, 3:35 PM MDT, 10 hours 20 minutes earlier.

Area forecast discussion, Aug 16, 3:35 PM MDT, 10 hours 20 minutes before

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Hazardous weather outlook, Aug 16, 11:02 AM MDT, 14 hours 53 minutes before

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The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 16, 6:25 PM MDT	Special Weather Statement	BOU	Washington	50 min
Aug 16, 7:51 PM MDT	Special Weather Statement	BOU	Lincoln	39 min
Aug 17, 1:47 AM MDT	Special Weather Statement	BOU	Weld	28 min
Aug 17, 2:24 AM MDT	Areal Flood Advisory	BOU	Weld	81 min
Aug 17, 2:59 AM MDT	Areal Flood Advisory	BOU	Weld	91 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2020 Every severe thunderstorm warning in 2020

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.