Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 113, NWS Cheyenne, WY

July 30, 2021Laramie County, Platte County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Jul 30, 2021, 5:23 PM MDT for Laramie County, Platte County, Wyoming. It was in force for 37 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: Jul 30, 2021, 5:23 PM MDT (23:23 UTC)
Expired: Jul 30, 2021, 6:00 PM MDT
In force: 37 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Laramie County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 56 km from the middle of the area, began a volume at 23:26 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 12:00Z, 11.4 hours before the alert went out and 242 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2523 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -18 m²/s²
0-3 km storm-relative helicity: 2 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

821 
WUUS55 KCYS 302323
SVRCYS
WYC021-031-310000-
/O.NEW.KCYS.SV.W.0113.210730T2323Z-210731T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cheyenne WY
523 PM MDT Fri Jul 30 2021

The National Weather Service in Cheyenne has issued a

* Severe Thunderstorm Warning for...
  Northwestern Laramie County in southeastern Wyoming...
  South central Platte County in southeastern Wyoming...

* Until 600 PM MDT.

* At 523 PM MDT, severe thunderstorms were located along a line
  extending from near Chugwater to 16 miles southwest of Slater to 8
  miles northeast of Iron Mountain, moving southeast at 5 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Chugwater.

This includes Interstate 25 in Wyoming between mile markers 40 and
53.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4167 10470 4157 10480 4150 10510 4168 10518
      4179 10490
TIME...MOT...LOC 2323Z 309DEG 5KT 4179 10478 4167 10495 4163 10510 

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

Brothers

1 follow-up statement

517 
WWUS55 KCYS 302359
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
559 PM MDT Fri Jul 30 2021

WYC021-031-310007-
/O.EXP.KCYS.SV.W.0113.000000T0000Z-210731T0000Z/
Laramie WY-Platte WY-
559 PM MDT Fri Jul 30 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN LARAMIE AND SOUTH
CENTRAL PLATTE COUNTIES WILL EXPIRE AT 600 PM MDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However heavy 
rain is still possible with these thunderstorms. Flooding is ongoing 
along and near Chugwater Creek where a Flash Flood Warning remains 
in effect through 845 PM MDT.

LAT...LON 4167 10470 4157 10480 4150 10510 4168 10518
      4179 10490
TIME...MOT...LOC 2357Z 309DEG 5KT 4176 10473 4164 10490 4160 10505 

$$

Brothers

The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 29, 7:44 PM MDT	Areal Flood Advisory	CYS	Albany, Carbon	89 min
Jul 29, 10:21 PM MDT	Special Weather Statement	CYS	Converse	39 min
Jul 29, 11:06 PM MDT	Special Weather Statement	CYS	Converse	39 min
Jul 29, 11:44 PM MDT	Special Weather Statement	CYS	Converse	46 min
Jul 30, 12:29 AM MDT	Special Weather Statement	CYS	Converse, Niobrara	61 min
Jul 30, 12:54 AM MDT	Areal Flood Advisory	CYS	Niobrara	3 hr
Jul 30, 12:57 AM MDT	Special Weather Statement	CYS	Converse	33 min
Jul 30, 1:29 AM MDT	Special Weather Statement	CYS	Converse	31 min
Jul 30, 2:05 AM MDT	Special Weather Statement	CYS	Niobrara	25 min
Jul 30, 3:15 PM MDT	Special Weather Statement	CYS	Laramie	45 min
Jul 30, 3:22 PM MDT	Areal Flood Advisory	CYS	Albany, Laramie	113 min
Jul 30, 3:33 PM MDT	Flash Flood Warning	CYS	Albany, Carbon	3 hr
Jul 30, 3:48 PM MDT	Special Weather Statement	CYS	Platte	27 min
Jul 30, 4:38 PM MDT	Special Weather Statement	CYS	Platte	37 min
Jul 30, 4:51 PM MDT	Special Weather Statement	CYS	Albany	39 min
Jul 30, 5:19 PM MDT	Special Weather Statement	CYS	Platte	41 min
Jul 30, 5:46 PM MDT	Flash Flood Warning	CYS	Laramie, Platte	2 hr
Jul 30, 5:52 PM MDT	Special Weather Statement	CYS	Converse	38 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 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.