Alert archive / Colorado / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 74, NWS Denver/Boulder, CO

June 18, 2021Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jun 18, 2021, 8:57 PM MDT for Weld County, Colorado. It was in force for 33 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jun 18, 2021, 8:57 PM MDT (02:57 UTC)
Expired
Jun 18, 2021, 9:30 PM MDT
In force
33 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), 47 km from the middle of the area, began a volume at 02:59 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, 3.0 hours before the alert went out and 150 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, Denver, CO at 00:00Z on 2021-06-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 580 joules per kilogram.LCLLFCEL10008507005003002001001 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, Denver, CO at 00:00Z on 2021-06-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 square meters per square second.193958Sfc1 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
580 J/kg
Mixed-layer CIN
-27 J/kg
Mixed-layer LCL
2917 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
35 m²/s²
0-3 km storm-relative helicity
78 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

The text

As transmitted.

040 
WUUS55 KBOU 190257
SVRBOU
COC123-190330-
/O.NEW.KBOU.SV.W.0074.210619T0257Z-210619T0330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Denver CO
857 PM MDT Fri Jun 18 2021

The National Weather Service in Denver Colorado has issued a

* Severe Thunderstorm Warning for...
  North central Weld County in northeastern Colorado...

* Until 930 PM MDT.

* At 856 PM MDT, a severe thunderstorm was located 5 miles west of
  Carpenter, or 21 miles southeast of Cheyenne, moving southeast at
  20 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees. Hail damage to 
           vehicles is expected.

* Locations impacted include...
  Hereford.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4084 10427 4094 10448 4100 10448 4100 10419
TIME...MOT...LOC 0256Z 301DEG 18KT 4100 10443 

HAIL...1.00IN
WIND...60MPH
 
$$

MEIER
1 follow-up statement
746 
WWUS55 KBOU 190328
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
928 PM MDT Fri Jun 18 2021

COC123-190338-
/O.EXP.KBOU.SV.W.0074.000000T0000Z-210619T0330Z/
Weld CO-
928 PM MDT Fri Jun 18 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL WELD COUNTY WILL
EXPIRE AT 930 PM MDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

LAT...LON 4084 10427 4094 10448 4100 10448 4100 10419
TIME...MOT...LOC 0328Z 301DEG 18KT 4092 10425 

$$

MEIER

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 19, 11:54 AM MDTFire Weather WatchBOUGrand, Jackson, Summit15 hr
Jun 19, 1:25 PM MDTSpecial Weather StatementBOUArapahoe35 min
Jun 19, 1:57 PM MDTSpecial Weather StatementBOUDenver33 min
Jun 19, 2:09 PM MDTTornado Warning Tornado observedBOUAdams36 min
Jun 19, 2:40 PM MDTTornado WarningBOUMorgan35 min
Jun 19, 2:52 PM MDTTornado WarningBOUAdams23 min
Jun 19, 2:54 PM MDTTornado WarningBOUElbert21 min
Jun 19, 3:14 PM MDTSevere Thunderstorm WarningBOUWeld31 min
Jun 19, 3:26 PM MDTSevere Thunderstorm WarningBOUAdams, Washington34 min
Jun 19, 3:33 PM MDTSevere Thunderstorm WarningBOUWashington27 min
Jun 19, 3:35 PM MDTSpecial Weather StatementBOUWashington55 min
Jun 19, 3:41 PM MDTSevere Thunderstorm WarningBOUElbert, Lincoln49 min
Jun 19, 3:55 PM MDTSevere Thunderstorm WarningBOUWashington50 min
Jun 19, 4:04 PM MDTSevere Thunderstorm WarningBOULogan41 min
Jun 19, 4:09 PM MDTSevere Thunderstorm WarningBOULincoln51 min
Jun 19, 4:12 PM MDTTornado WarningBOUWashington33 min
Jun 19, 4:15 PM MDTTornado WarningBOULogan30 min
Jun 19, 4:37 PM MDTSevere Thunderstorm WarningBOUWashington38 min
Jun 19, 4:49 PM MDTSevere Thunderstorm WarningBOULogan, Phillips, Sedgwick41 min
Jun 19, 4:57 PM MDTSevere Thunderstorm WarningBOULincoln33 min
Jun 19, 5:16 PM MDTSevere Thunderstorm WarningBOUPhillips, Sedgwick29 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2021Every severe thunderstorm warning 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.