Alert archive / Colorado / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 122, NWS Denver/Boulder, CO

August 14, 2021Logan County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 14, 2021, 8:01 PM MDT for Logan County, Colorado. It was in force for 44 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: Aug 14, 2021, 8:01 PM MDT (02:01 UTC)
Expired: Aug 14, 2021, 8:45 PM MDT
In force: 44 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Damage threat: Considerable
Hail: 1.75 in
Wind: 60.0 mph

County Logan County, CO

The radar

The Cheyenne radar (KCYS), 140 km from the middle of the area, began a volume at 02:04 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 14, 3:28 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Denver, CO (KDNR), launched 00:00Z, 2.0 hours before the alert went out and 105 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: 666 J/kg
Mixed-layer CIN: -45 J/kg
Mixed-layer LCL: 3335 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: 81 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

As transmitted.

548 
WUUS55 KBOU 150201
SVRBOU
COC075-150245-
/O.NEW.KBOU.SV.W.0122.210815T0201Z-210815T0245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Denver CO
801 PM MDT Sat Aug 14 2021

The National Weather Service in Denver Colorado has issued a

* Severe Thunderstorm Warning for...
  Northwestern Logan County in northeastern Colorado...

* Until 845 PM MDT.

* At 801 PM MDT, a severe thunderstorm was located 9 miles northeast
  of Westplains, or 23 miles north of Sterling, moving south at 15
  mph.

  HAZARD...Golf ball size hail and 60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees. People and 
           animals outdoors will be injured. Expect hail damage to 
           roofs, siding, windows, and vehicles.

* Locations impacted include...
  North Sterling Reservoir and Padroni.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm is producing large hail. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows!

&&

LAT...LON 4072 10301 4061 10341 4100 10344 4100 10316
TIME...MOT...LOC 0201Z 343DEG 14KT 4094 10334 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

BARJENBRUCH

1 follow-up statement

672 
WWUS55 KBOU 150230
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
830 PM MDT Sat Aug 14 2021

COC075-150245-
/O.CON.KBOU.SV.W.0122.000000T0000Z-210815T0245Z/
Logan CO-
830 PM MDT Sat Aug 14 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 845 PM MDT
FOR WEST CENTRAL LOGAN COUNTY...

At 830 PM MDT, a severe thunderstorm was located near North Sterling
Reservoir, or 11 miles northwest of Sterling, moving south at 25 mph.

HAZARD...Golf ball size hail.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect damage 
         to roofs, siding, windows, and vehicles.

Locations impacted include...
Padroni, North Sterling Reservoir and Logan Corners. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm is producing large hail. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows.

&&

LAT...LON 4061 10341 4087 10339 4088 10321 4070 10307
TIME...MOT...LOC 0230Z 349DEG 22KT 4076 10332 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

BARJENBRUCH

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 14, 6:48 PM MDT	Flash Flood Warning	BOU	Larimer	115 min
Aug 14, 7:15 PM MDT	Special Weather Statement	BOU	Summit	30 min
Aug 14, 7:38 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Weld	52 min
Aug 14, 8:28 PM MDT	Severe Thunderstorm Warning	BOU	Weld	47 min
Aug 14, 8:29 PM MDT	Severe Thunderstorm Warning	BOU	Sedgwick	46 min
Aug 14, 8:43 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Logan, Washington	47 min
Aug 14, 9:15 PM MDT	Severe Thunderstorm Warning	BOU	Phillips, Sedgwick	14 min
Aug 14, 9:28 PM MDT	Severe Thunderstorm Warning	BOU	Logan, Washington	47 min
Aug 14, 9:31 PM MDT	Special Weather Statement	BOU	Weld	44 min
Aug 15, 2:32 PM MDT	Areal Flood Advisory	BOU	Grand	88 min
Aug 15, 5:19 PM MDT	Special Weather Statement	BOU	Lincoln	41 min
Aug 15, 5:25 PM MDT	Special Weather Statement	BOU	Teller	65 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2021 Every 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.