Alert archive / Wyoming / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 252, NWS Cheyenne, WY

August 7, 2018Laramie County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Aug 7, 2018, 4:50 PM MDT for Laramie County, Wyoming. It was in force for 25 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 7, 2018, 4:50 PM MDT (22:50 UTC)
Expired: Aug 7, 2018, 5:15 PM MDT
In force: 25 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Laramie County, WY

The radar

The Cheyenne radar (KCYS), 29 km from the middle of the area, began a volume at 22:51 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 (KDEN), launched 12:00Z, 10.8 hours before the alert went out and 182 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: 570 J/kg
Mixed-layer CIN: -127 J/kg
Mixed-layer LCL: 1535 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: -12 m²/s²
0-3 km storm-relative helicity: 25 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted.

076 
WUUS55 KCYS 072250
SVRCYS
WYC021-072315-
/O.NEW.KCYS.SV.W.0252.180807T2250Z-180807T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cheyenne WY
450 PM MDT TUE AUG 7 2018

The National Weather Service in Cheyenne has issued a

* Severe Thunderstorm Warning for...
  Southeastern Laramie County in southeastern Wyoming...

* Until 515 PM MDT.

* At 449 PM MDT, a severe thunderstorm was located near Hillsdale, or
  12 miles east of Cheyenne, moving east at 25 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* Locations impacted include...
  Burns and Hillsdale. 

This includes Interstate 80 in Wyoming between mile markers 372 and
385.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4114 10463 4123 10466 4133 10425 4117 10419
TIME...MOT...LOC 2249Z 251DEG 21KT 4119 10457 

HAIL...1.00IN
WIND...<50MPH
 
$$

Braun

1 follow-up statement

788 
WWUS55 KCYS 072308
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
508 PM MDT TUE AUG 7 2018

WYC021-072318-
/O.EXP.KCYS.SV.W.0252.000000T0000Z-180807T2315Z/
Laramie WY-
508 PM MDT TUE AUG 7 2018

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN LARAMIE COUNTY
WILL EXPIRE AT 515 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.  However small hail
and heavy rain are still possible with this thunderstorm.

LAT...LON 4114 10463 4123 10466 4133 10425 4117 10419
TIME...MOT...LOC 2308Z 251DEG 21KT 4122 10445 

$$

Braun

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 6, 6:05 PM MDT	Special Weather Statement	CYS	Laramie	25 min
Aug 6, 6:29 PM MDT	Special Weather Statement	CYS	Laramie	31 min
Aug 7, 1:46 PM MDT	Special Weather Statement	CYS	Laramie	44 min
Aug 7, 2:14 PM MDT	Special Weather Statement	CYS	Laramie	46 min
Aug 7, 3:12 PM MDT	Special Weather Statement	CYS	Laramie	33 min
Aug 7, 3:25 PM MDT	Special Weather Statement	CYS	Laramie	50 min
Aug 7, 3:35 PM MDT	Special Weather Statement	CYS	Laramie	25 min
Aug 7, 3:57 PM MDT	Areal Flood Advisory	CYS	Laramie	3 hr
Aug 7, 4:01 PM MDT	Special Weather Statement	CYS	Laramie	29 min
Aug 7, 4:05 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	25 min
Aug 7, 4:06 PM MDT	Flash Flood Warning	CYS	Laramie	3 hr
Aug 7, 4:09 PM MDT	Special Weather Statement	CYS	Laramie	51 min
Aug 7, 4:27 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	48 min
Aug 7, 5:06 PM MDT	Special Weather Statement	CYS	Laramie	39 min
Aug 7, 5:11 PM MDT	Special Weather Statement	CYS	Laramie	34 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2018 Every severe thunderstorm warning in 2018

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.