Alert archive / Wyoming / Special Weather Statements in 2021

Special Weather Statement, NWS Riverton, WY

August 6, 2021Natrona County, Wyoming

NWS Riverton, WY issued this special weather statement at Aug 6, 2021, 2:21 PM MDT for Natrona County, Wyoming. It was in force for 39 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 6, 2021, 2:21 PM MDT (20:21 UTC)
Expired: Aug 6, 2021, 3:00 PM MDT
In force: 39 min
Issued by: NWS Riverton, WY
Hail: 0.75 in
Wind: 40

County Natrona County, WY

The radar

The Riverton/Lander radar (KRIW), 178 km from the middle of the area, began a volume at 20:23 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

Riverton, WY (KRIW), launched 12:00Z, 8.4 hours before the alert went out and 171 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: 1589 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 69 m²/s²
0-3 km storm-relative helicity: 150 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

117 
WWUS85 KRIW 062021
SPSRIW

Special Weather Statement
National Weather Service Riverton WY
221 PM MDT Fri Aug 6 2021
 
WYZ020-062100-
Natrona County Lower Elevations-
221 PM MDT Fri Aug 6 2021

...A strong thunderstorm will impact portions of east central Natrona
County through 300 PM MDT...

At 220 PM MDT, Doppler radar was tracking a strong thunderstorm over
Antelope Hills, or 16 miles north of Casper, moving northeast at 25
mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects. Minor damage to outdoor objects is 
         possible.

This strong thunderstorm will be near...
  Antelope Hills around 225 PM MDT.

This includes Interstate 25 between mile markers 197 and 213.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

Heavy rainfall is also occurring with this storm and may lead to 
localized flooding. Do not drive your vehicle through flooded 
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
central Wyoming.

&&

LAT...LON 4295 10640 4311 10651 4338 10607 4302 10608
TIME...MOT...LOC 2020Z 242DEG 23KT 4307 10637 

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

$$

Vorst

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 5, 10:47 PM MDT	Special Weather Statement	RIW	Teton	28 min
Aug 5, 11:25 PM MDT	Special Weather Statement	RIW		20 min
Aug 6, 8:10 AM MDT	Special Weather Statement	RIW		35 min
Aug 6, 9:29 AM MDT	Special Weather Statement	RIW		31 min
Aug 6, 10:01 AM MDT	Special Weather Statement	RIW		29 min
Aug 6, 10:33 AM MDT	Special Weather Statement	RIW	Hot Springs	27 min
Aug 6, 10:59 AM MDT	Special Weather Statement	RIW	Hot Springs	31 min
Aug 6, 1:12 PM MDT	Special Weather Statement	RIW	Hot Springs	33 min
Aug 6, 1:36 PM MDT	Special Weather Statement	RIW	Natrona	24 min
Aug 6, 2:09 PM MDT	Special Weather Statement	RIW	Natrona	36 min
Aug 6, 2:12 PM MDT	Special Weather Statement	RIW	Natrona	33 min
Aug 6, 2:31 PM MDT	Special Weather Statement	RIW	Sublette	29 min
Aug 6, 2:39 PM MDT	Special Weather Statement	RIW	Fremont	36 min
Aug 6, 2:43 PM MDT	Special Weather Statement	RIW		32 min
Aug 6, 3:08 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	37 min
Aug 6, 3:17 PM MDT	Special Weather Statement	RIW		28 min
Aug 6, 3:21 PM MDT	Special Weather Statement	RIW	Fremont	24 min
Aug 6, 3:40 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	35 min
Aug 6, 3:47 PM MDT	Severe Thunderstorm Warning	RIW	Fremont	28 min
Aug 6, 3:57 PM MDT	Special Weather Statement	RIW	Sublette	33 min
Aug 6, 4:14 PM MDT	Special Weather Statement	RIW	Sublette	31 min
Aug 6, 4:16 PM MDT	Special Weather Statement	RIW	Fremont	29 min
Aug 6, 4:21 PM MDT	Special Weather Statement	RIW		24 min
Aug 6, 4:41 PM MDT	Special Weather Statement	RIW	Natrona	34 min
Aug 6, 4:44 PM MDT	Special Weather Statement	RIW		31 min
Aug 6, 4:45 PM MDT	Special Weather Statement	RIW	Teton	30 min
Aug 6, 4:53 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	37 min
Aug 6, 5:23 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	37 min
Aug 6, 5:54 PM MDT	Special Weather Statement	RIW	Johnson	36 min
Aug 6, 5:55 PM MDT	Special Weather Statement	RIW	Natrona	35 min

Nearby

Special Weather Statements in Wyoming, 2021 Every special weather statement 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.