Alert archive / Colorado / Severe Thunderstorm Warnings in 2024

Severe Thunderstorm Warning 229, NWS Denver/Boulder, CO

August 11, 2024Adams County, Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 11, 2024, 5:41 PM MDT for Adams County, Weld County, Colorado. It was in force for 31 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 11, 2024, 5:41 PM MDT (23:41 UTC)
Expired
Aug 11, 2024, 6:12 PM MDT
In force
31 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Adams County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 50 km from the middle of the area, began a volume at 23:45 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.7 hours before the alert went out and 333 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-pSkew-T log-p diagram, N. Platte/Lee Bi, NE at 12:00Z on 2024-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, N. Platte/Lee Bi, NE at 12:00Z on 2024-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 94 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
952 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
94 m²/s²
0-3 km storm-relative helicity
249 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 11, 5:38 PM MDT, 3 minutes earlier.

Area forecast discussion, Aug 11, 5:38 PM MDT, 3 minutes before
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Hazardous weather outlook, Aug 11, 10:59 AM MDT, 6 hours 42 minutes before
Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1059 AM MDT Sun Aug 11 2024

COZ030>051-121700-
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-
1059 AM MDT Sun Aug 11 2024

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

.DAY ONE...Today and Tonight

Scattered thunderstorms are expected to redevelop over the
mountains by early afternoon and then spread and develop eastward
across the plains through the late afternoon hours. A couple
storms will likely become severe, mainly along and east of a
Sterling to Akron to Limon line where more instability exists. The
main threat is damaging wind gusts to around 60 mph, but large
hail is also possible.

The recent burn scars will see a limited threat of flash flooding,
as storms will be moving along and intensity of storms in/near the
mountains is expected to be a little less than yesterday.

Storms will diminish from northwest to southeast across the area
this evening.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Scattered to numerous showers and storms are expected to start the
week, most numerous over the high country and Palmer Divide.
Locally heavy rainfall is possible with the stronger storms that
could elevate the flash flood threat for sensitive areas like our
burn scars. A couple of storms could become severe Monday and
Monday evening with possibly a higher threat on Tuesday.

There will be a gradual warming and drying trend Wednesday
through Friday, with thunderstorm activity returning to a more
typical summer convective pattern as the week persists.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight. However,
any reports of heavy rainfall, strong wind gusts, or hail will be
appreciated.

In the hours before

Local storm report, Aug 11, 12:49 PM MDT, 4 hours 52 minutes before
Preliminary Local Storm Report
National Weather Service Denver CO
1249 PM MDT Sun Aug 11 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0238 PM     Flash Flood      2 WNW Cedar Cove        40.42N 105.29W
08/07/2024                   Larimer            CO   NWS Employee

            Delayed Report: Several rocks laying across
            Hwy 34, right off the Alexander Mountain
            burn scar.

&&

GH
Special weather statement, Aug 11, 1:36 PM MDT, 4 hours 5 minutes before
Special Weather Statement
National Weather Service Denver CO
136 PM MDT Sun Aug 11 2024

COZ038-042-048-112015-
Logan County CO-Northeast Weld County CO-
Larimer County Below 6000 Feet/Northwest Weld County CO-
136 PM MDT Sun Aug 11 2024

...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN WELD AND WEST
CENTRAL LOGAN COUNTIES THROUGH 215 PM MDT...

At 136 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 13 miles northeast of
Pawnee Buttes to 6 miles southwest of Panorama Point to 4 miles
southwest of Hereford, or along a line extending from 19 miles
southwest of Kimball to 50 miles north of Fort Morgan to 27 miles
southeast of Cheyenne. Movement was southeast at 30 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Grover, New Raymer, Keota, Hereford, Stoneham, and Pawnee Buttes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4067 10332 4059 10376 4059 10430 4096 10449
      4100 10410 4100 10376
TIME...MOT...LOC 1936Z 322DEG 24KT 4099 10387 4095 10412 4092 10435

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

HEAVENER
Special weather statement, Aug 11, 2:21 PM MDT, 3 hours 20 minutes before
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Special weather statement, Aug 11, 2:27 PM MDT, 3 hours 14 minutes before
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Local storm report, Aug 11, 3:20 PM MDT, 2 hours 21 minutes before
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Special weather statement, Aug 11, 5:15 PM MDT, 26 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 10, 9:57 PM MDTAreal Flood AdvisoryBOUDouglas, Elbert3 hr
Aug 11, 2:21 PM MDTSpecial Weather StatementBOULogan39 min
Aug 11, 2:27 PM MDTSpecial Weather StatementBOUWeld48 min
Aug 11, 2:41 PM MDTSevere Thunderstorm WarningBOULogan49 min
Aug 11, 3:23 PM MDTSevere Thunderstorm WarningBOULogan, Phillips21 min
Aug 11, 5:15 PM MDTSpecial Weather StatementBOUBroomfield45 min
Aug 11, 5:56 PM MDTSpecial Weather StatementBOUMorgan49 min
Aug 11, 5:59 PM MDTSpecial Weather StatementBOUDenver46 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2024Every 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.