Alert archive / Wyoming / Severe Thunderstorm Warnings in 2019

Severe Thunderstorm Warning 229, NWS Cheyenne, WY

July 12, 2019Laramie County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Jul 12, 2019, 2:09 PM MDT for Laramie County, Wyoming. It was in force for 51 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: Jul 12, 2019, 2:09 PM MDT (20:09 UTC)
Expired: Jul 12, 2019, 3:00 PM MDT
In force: 51 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Laramie County, WY

The radar

The Cheyenne radar (KCYS), 20 km from the middle of the area, began a volume at 20:11 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, 8.2 hours before the alert went out and 202 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: 61 J/kg
Mixed-layer CIN: -311 J/kg
Mixed-layer LCL: 3439 m above ground
0-6 km bulk shear: 4 kt
0-1 km storm-relative helicity: -14 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

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 Cheyenne, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 12, 11:32 AM MDT, 2 hours 37 minutes earlier.

Area forecast discussion, Jul 12, 11:32 AM MDT, 2 hours 37 minutes before

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Hazardous weather outlook, Jul 12, 3:59 AM MDT, 10 hours 10 minutes before

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In the hours before

Special weather statement, Jul 12, 12:39 PM MDT, 1 hour 30 minutes before

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Special weather statement, Jul 12, 1:13 PM MDT, 56 minutes before

Special Weather Statement
National Weather Service Cheyenne WY
113 PM MDT Fri Jul 12 2019

WYZ116>118-121945-
South Laramie Range WY-Central Laramie County WY-
South Laramie Range Foothills WY-
113 PM MDT Fri Jul 12 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN ALBANY AND
SOUTHWESTERN LARAMIE COUNTIES UNTIL 145 PM MDT...

At 113 PM MDT, Doppler radar was tracking a strong thunderstorm near
Buford, or 23 miles west of Cheyenne, moving northeast at 25 mph.

Half inch hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Crystal Lake Campground and Crystal Lake Reservoir.

This includes the following highways...
 Interstate 25 in Wyoming between mile markers 6 and 7.
 Interstate 80 in Wyoming between mile markers 337 and 358.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Cheyenne.

&&

LAT...LON 4105 10536 4130 10505 4108 10483 4100 10514
      4100 10530
TIME...MOT...LOC 1913Z 231DEG 20KT 4103 10522

Hammer

Special weather statement, Jul 12, 1:44 PM MDT, 25 minutes before

Special Weather Statement
National Weather Service Cheyenne WY
144 PM MDT Fri Jul 12 2019

WYZ116>118-122015-
South Laramie Range WY-Central Laramie County WY-
South Laramie Range Foothills WY-
144 PM MDT Fri Jul 12 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN LARAMIE COUNTY UNTIL
215 PM MDT...

At 144 PM MDT, Doppler radar was tracking a strong thunderstorm near
Crystal Lake Campground, or 16 miles west of Cheyenne, moving
northeast at 15 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Crystal Lake Reservoir, Crystal Lake Campground, Warren AFB and
Ranchettes.

This includes the following highways...
 Interstate 25 in Wyoming between mile markers 5 and 7.
 Interstate 80 in Wyoming between mile markers 343 and 359.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm 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.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Cheyenne.

&&

LAT...LON 4100 10512 4116 10521 4135 10494 4107 10484
TIME...MOT...LOC 1944Z 237DEG 12KT 4112 10510

Hammer

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 12, 12:39 PM MDT	Special Weather Statement	CYS	Platte	51 min
Jul 12, 1:13 PM MDT	Special Weather Statement	CYS	Laramie	32 min
Jul 12, 1:44 PM MDT	Special Weather Statement	CYS	Laramie	31 min
Jul 12, 2:58 PM MDT	Special Weather Statement	CYS	Laramie	47 min
Jul 12, 4:45 PM MDT	Special Weather Statement	CYS	Converse	45 min
Jul 12, 4:50 PM MDT	Severe Thunderstorm Warning	CYS	Converse	25 min
Jul 12, 5:49 PM MDT	Severe Thunderstorm Warning	CYS	Goshen, Niobrara	26 min
Jul 12, 5:27 PM MDT	Special Weather Statement	CYS	Sioux	48 min
Jul 12, 5:36 PM MDT	Special Weather Statement	CYS	Box Butte	39 min
Jul 12, 5:44 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Morrill	31 min
Jul 12, 5:54 PM MDT	Special Weather Statement	CYS	Cheyenne	51 min
Jul 12, 5:58 PM MDT	Tornado Warning Tornado observed	CYS	Cheyenne	32 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2019 Every severe thunderstorm warning in 2019

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.