Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 4, NWS Riverton, WY

July 5, 2021Fremont County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Jul 5, 2021, 5:25 PM MDT for Fremont County, Wyoming. It was in force for 35 min. 2 reports 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 5, 2021, 5:25 PM MDT (23:25 UTC)
Expired: Jul 5, 2021, 6:00 PM MDT
In force: 35 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Hail: 0.88 in
Wind: 60.0 mph

County Fremont County, WY

The radar

The Riverton/Lander radar (KRIW), 34 km from the middle of the area, began a volume at 23:25 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 5, 5:42 PM MDT	TSTM WND GST 53	6 Wnw Sweetwater Statio, WY	MESONET STATION KBVR BEAVER RIM (WYDOT).
Jul 5, 5:46 PM MDT	TSTM WND GST 52	4 Nnw Hudson, WY	MESONET STATION SHPW4 HUDSON 3 NNW.

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, 11.4 hours before the alert went out and 28 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: 24 J/kg
Mixed-layer CIN: -300 J/kg
Mixed-layer LCL: 1993 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 36 m²/s²
0-3 km storm-relative helicity: 54 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

625 
WUUS55 KRIW 052325
SVRRIW
WYC013-060000-
/O.NEW.KRIW.SV.W.0004.210705T2325Z-210706T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Riverton WY
525 PM MDT Mon Jul 5 2021

The National Weather Service in Riverton has issued a

* Severe Thunderstorm Warning for...
  Southeastern Fremont County in central Wyoming...

* Until 600 PM MDT.

* At 524 PM MDT, severe thunderstorms were located along a line
  extending from 7 miles northeast of Pavillion to near Hudson to 9
  miles east of Red Canyon, moving east at 35 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Severe thunderstorms will be near...
  Riverton and Arapahoe around 535 PM MDT.

Other locations in the path of these severe thunderstorms include
Sweetwater Station, Hidden Valley and Shoshoni.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Hail and damaging winds and continuous cloud to ground lightning is 
occurring with these storms. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

&&

LAT...LON 4328 10776 4284 10783 4244 10766 4260 10848
      4295 10861 4327 10855
TIME...MOT...LOC 2324Z 280DEG 31KT 4330 10857 4295 10859 4262 10846 

HAIL...0.88IN
WIND...60MPH
 
$$

Vorst

2 follow-up statements

071 
WWUS55 KRIW 052343
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
543 PM MDT Mon Jul 5 2021

WYC013-060000-
/O.CON.KRIW.SV.W.0004.000000T0000Z-210706T0000Z/
Fremont-
543 PM MDT Mon Jul 5 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM MDT
FOR SOUTHEASTERN FREMONT COUNTY...

At 543 PM MDT, severe thunderstorms were located along a line
extending from near Hidden Valley to 9 miles southeast of Riverton to
near Sweetwater Station, moving east at 20 mph.

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

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
  Boysen State Park and Shoshoni.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

If on or near Boysen Reservoir, get away from the water and move 
indoors or inside a vehicle. remember, lightning can strike out to 
15 miles from the parent thunderstorm. If you can hear thunder, you 
are close enough to be struck by lightning. Move to safe shelter 
now!  Do not be caught on the water in a thunderstorm.

&&

LAT...LON 4325 10787 4292 10792 4249 10790 4251 10801
      4257 10832 4293 10836 4325 10831
TIME...MOT...LOC 2343Z 270DEG 19KT 4319 10823 4293 10827 4257 10824 

HAIL...0.75IN
WIND...60MPH
 
$$

Vorst

435 
WWUS55 KRIW 060000
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
600 PM MDT Mon Jul 5 2021

WYC013-060009-
/O.EXP.KRIW.SV.W.0004.000000T0000Z-210706T0000Z/
Fremont-
600 PM MDT Mon Jul 5 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN FREMONT COUNTY
WILL EXPIRE AT 600 PM MDT...
    
The storms which prompted the warning have weakened below severe
limits, and have exited the warned area. Therefore, the warning will
be allowed to expire.  However small hail, gusty winds and heavy rain
are still possible with these thunderstorms.

LAT...LON 4325 10787 4292 10792 4249 10790 4251 10801
      4257 10832 4293 10836 4325 10831
TIME...MOT...LOC 2359Z 280DEG 31KT 4317 10810 4291 10814 4255 10811 

$$

Vorst

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 4, 6:06 PM MDT	Special Weather Statement	RIW	Park	24 min
Jul 4, 7:47 PM MDT	Special Weather Statement	RIW	Fremont	28 min
Jul 4, 8:19 PM MDT	Special Weather Statement	RIW	Fremont	26 min
Jul 5, 2:04 PM MDT	Special Weather Statement	RIW		26 min
Jul 5, 2:15 PM MDT	Special Weather Statement	RIW	Teton	15 min
Jul 5, 3:26 PM MDT	Special Weather Statement	RIW		19 min
Jul 5, 4:58 PM MDT	Special Weather Statement	RIW	Fremont	32 min
Jul 5, 5:14 PM MDT	Special Weather Statement	RIW	Fremont	31 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.