Alert archive / Colorado / Severe Thunderstorm Warnings in 2024

Severe Thunderstorm Warning 201, NWS Denver/Boulder, CO

July 20, 2024Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 20, 2024, 7:54 PM MDT for Weld County, Colorado. It was in force for 36 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: Jul 20, 2024, 7:54 PM MDT (01:54 UTC)
Expired: Jul 20, 2024, 8:30 PM MDT
In force: 36 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Hail: 1.0 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 01:58 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

Grand Junction, CO (KGJT), launched 00:00Z, 1.9 hours before the alert went out and 385 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: 38 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 3750 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 39 m²/s²
0-3 km storm-relative helicity: 48 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 Jul 20, 5:47 PM MDT, 2 hours 7 minutes earlier.

Area forecast discussion, Jul 20, 5:47 PM MDT, 2 hours 7 minutes before

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Hazardous weather outlook, Jul 20, 10:47 AM MDT, 9 hours 7 minutes before

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1047 AM MDT Sat Jul 20 2024

COZ030>051-211700-
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Grand and Summit Counties Below 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Central and Southeast Park County-
Larimer County Below 6000 Feet/Northwest Weld County-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
Northeast Weld County-Central and South Weld County-Morgan County-
Central and East Adams and Arapahoe Counties-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County-
Southeast Elbert County Below 6000 Feet/South Lincoln County-
Logan County-Washington County-Sedgwick County-Phillips County-
1047 AM MDT Sat Jul 20 2024

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

Scattered showers and thunderstorms are expected this afternoon
and evening across the region. A few of the stronger storms could
produce small hail, gusty winds, and briefly heavy rainfall. A
limited threat exists for flash flooding over the burn scars.
Chances for showers and a few thunderstorms will continue through
the overnight hours.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Scattered showers and thunderstorms are expected Sunday with a
limited threat of burn area flash flooding. For next week, the
scattered late day showers and thunderstorms are forecast mainly
for the high country, with no or just a few storms out on the
plains through the week. The limited threat of burn area flash
flooding still exists on Monday, but not for the rest of the
week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected, but any reports of large hail
or gusty winds will be appreciated.

In the hours before

Special weather statement, Jul 20, 4:02 PM MDT, 3 hours 52 minutes before

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Local storm report, Jul 20, 4:26 PM MDT, 3 hours 28 minutes before

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Special weather statement, Jul 20, 5:03 PM MDT, 2 hours 51 minutes before

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Local storm report, Jul 20, 5:23 PM MDT, 2 hours 31 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
Jul 20, 6:22 PM MDT	Special Weather Statement	BOU	Washington	38 min
Jul 20, 7:08 PM MDT	Special Weather Statement	BOU	Lincoln	37 min
Jul 20, 7:11 PM MDT	Special Weather Statement	BOU	Larimer	34 min
Jul 20, 7:22 PM MDT	Severe Thunderstorm Warning	BOU	Larimer, Weld	23 min
Jul 20, 7:43 PM MDT	Severe Thunderstorm Warning	BOU	Boulder, Larimer, Weld	47 min
Jul 20, 7:49 PM MDT	Areal Flood Advisory	BOU	Larimer	3 hr
Jul 20, 8:24 PM MDT	Severe Thunderstorm Warning	BOU	Park	24 min
Jul 20, 8:32 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Boulder, Broomfield, Denver, Jefferson, Weld	28 min
Jul 20, 9:00 PM MDT	Special Weather Statement	BOU	Denver	30 min
Jul 20, 9:14 PM MDT	Areal Flood Advisory	BOU	Adams, Arapahoe, Denver	3 hr
Jul 20, 9:20 PM MDT	Severe Thunderstorm Warning	BOU	Arapahoe, Douglas, Elbert	25 min
Jul 20, 9:40 PM MDT	Special Weather Statement	BOU	Douglas	50 min
Jul 21, 12:55 PM MDT	Areal Flood Advisory	BOU	Grand	3 hr
Jul 21, 1:24 PM MDT	Special Weather Statement	BOU	Lincoln	36 min
Jul 21, 4:10 PM MDT	Special Weather Statement	BOU	Sedgwick	50 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2024 Every severe thunderstorm warning in 2024

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.