Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 6, NWS Riverton, WY

July 9, 2021Johnson County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Jul 9, 2021, 5:12 PM MDT for Johnson County, Wyoming. It was in force for 48 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 9, 2021, 5:12 PM MDT (23:12 UTC)
Expired: Jul 9, 2021, 6:00 PM MDT
In force: 48 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Johnson County, WY

The radar

The Riverton/Lander radar (KRIW), 222 km from the middle of the area, began a volume at 23:13 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.

What was reported inside it

Time	Report	Where	Remark
Jul 9, 5:36 PM MDT	HAIL 1	14 E Buffalo, WY	WINDS TO AROUND 20 MPH WITH QUARTER-SIZED HAIL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 11.2 hours before the alert went out and 217 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: 2505 m above ground
0-6 km bulk shear: 65 kt
0-1 km storm-relative helicity: 219 m²/s²
0-3 km storm-relative helicity: 312 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

172 
WUUS55 KRIW 092312
SVRRIW
WYC019-100000-
/O.NEW.KRIW.SV.W.0006.210709T2312Z-210710T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Riverton WY
512 PM MDT Fri Jul 9 2021

The National Weather Service in Riverton has issued a

* Severe Thunderstorm Warning for...
  North central Johnson County in north central Wyoming...

* Until 600 PM MDT.

* At 512 PM MDT, a severe thunderstorm was located over Fort Phil
  Kearny Historical Site, or 13 miles north of Buffalo, moving east
  at 35 mph.

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

  SOURCE...Trained weather spotters.

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

* This severe thunderstorm will remain over mainly rural areas of
  north central Johnson County, including the following locations...
  Buffalo Johnson County Airport and Johnson County Fairgrounds.

This includes the following highways...
 Interstate 25 between mile markers 296 and 299.
 Interstate 90 between mile markers 42 and 72.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4454 10622 4418 10649 4447 10695 4456 10690
      4456 10638
TIME...MOT...LOC 2312Z 291DEG 32KT 4453 10680 

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

Vorst

2 follow-up statements

200 
WWUS55 KRIW 092329
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
529 PM MDT Fri Jul 9 2021

WYC019-100000-
/O.CON.KRIW.SV.W.0006.000000T0000Z-210710T0000Z/
Johnson-
529 PM MDT Fri Jul 9 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM MDT
FOR NORTH CENTRAL JOHNSON COUNTY...

At 529 PM MDT, a severe thunderstorm was located 7 miles east of Lake
De Smet, or 10 miles northeast of Buffalo, moving east at 35 mph.

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

SOURCE...Trained weather spotters.

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

Locations impacted include...
Buffalo, Lake De Smet, Buffalo Johnson County Airport and Johnson
County Fairgrounds.

This includes the following highways...
 Interstate 25 between mile markers 296 and 299.
 Interstate 90 between mile markers 49 and 72.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4454 10622 4418 10649 4438 10680 4456 10678
      4456 10638
TIME...MOT...LOC 2329Z 291DEG 32KT 4448 10660 

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

Vorst

007 
WWUS55 KRIW 092350
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
550 PM MDT Fri Jul 9 2021

WYC019-100000-
/O.EXP.KRIW.SV.W.0006.000000T0000Z-210710T0000Z/
Johnson-
550 PM MDT Fri Jul 9 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL JOHNSON COUNTY
WILL EXPIRE AT 600 PM MDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.  However gusty winds are still possible with
this thunderstorm.

LAT...LON 4454 10622 4418 10649 4438 10680 4456 10678
      4456 10638
TIME...MOT...LOC 2350Z 291DEG 32KT 4442 10638 

$$

Vorst

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 5:43 PM MDT	Special Weather Statement	RIW	Johnson	32 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.