Alert archive / Wyoming / Special Weather Statements in 2021

Special Weather Statement, NWS Riverton, WY

September 2, 2021

NWS Riverton, WY issued this special weather statement at Sep 2, 2021, 4:02 PM MDT. It was in force for 28 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: Sep 2, 2021, 4:02 PM MDT (22:02 UTC)
Expired: Sep 2, 2021, 4:30 PM MDT
In force: 28 min
Issued by: NWS Riverton, WY
Hail: 0.50 in
Wind: 30

The radar

The Riverton/Lander radar (KRIW), 85 km from the middle of the area, began a volume at 22:04 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, 10.0 hours before the alert went out and 90 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: 31 J/kg
Mixed-layer CIN: -197 J/kg
Mixed-layer LCL: 1437 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 24 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Riverton, WY wrote its last area forecast discussion before this special weather statement went out at Sep 2, 2:27 PM MDT, 1 hour 35 minutes earlier.

Area forecast discussion, Sep 2, 2:27 PM MDT, 1 hour 35 minutes before

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Hazardous weather outlook, Sep 2, 3:04 PM MDT, 58 minutes before

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In the hours before

Special weather statement, Sep 2, 2:21 PM MDT, 1 hour 41 minutes before

Special Weather Statement
National Weather Service Riverton WY
221 PM MDT Thu Sep 2 2021

WYZ007-009-017>020-022045-
Owl Creek and Bridger Mountains-Wind River Basin-Bighorn Mountains
Southeast-Green Mountains and Rattlesnake Range-Natrona County Lower
Elevations-Lander Foothills-
221 PM MDT Thu Sep 2 2021

...Strong thunderstorms will impact portions of northwestern Natrona
and southeastern Fremont Counties through 245 PM MDT...

At 220 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 9 miles northwest of Lysite to 8 miles
southeast of Red Canyon. Movement was southeast at 40 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Strong thunderstorms will be near...
  Lysite around 235 PM MDT.
  Lost Cabin around 240 PM MDT.

Other locations in the path of these storms include Sweetwater
Station.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

If on or near Boysen Reservoir, get out of the water and move
indoors or inside a vehicle. Remember, lightning can strike out to
10 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 4332 10716 4229 10795 4272 10863 4340 10807
TIME...MOT...LOC 2020Z 293DEG 36KT 4335 10786 4258 10851

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

Vorst

Special weather statement, Sep 2, 2:33 PM MDT, 1 hour 29 minutes before

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Special weather statement, Sep 2, 3:01 PM MDT, 1 hour 1 minute before

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Special weather statement, Sep 2, 3:21 PM MDT, 41 minutes before

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Special weather statement, Sep 2, 3:30 PM MDT, 32 minutes before

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Special weather statement, Sep 2, 4:02 PM MDT, 0 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 2, 10:28 AM MDT	Special Weather Statement	RIW		47 min
Sep 2, 11:19 AM MDT	Special Weather Statement	RIW	Sublette	41 min
Sep 2, 1:34 PM MDT	Special Weather Statement	RIW	Fremont	26 min
Sep 2, 1:50 PM MDT	Severe Thunderstorm Warning	RIW	Fremont	40 min
Sep 2, 2:21 PM MDT	Special Weather Statement	RIW		24 min
Sep 2, 2:33 PM MDT	Special Weather Statement	RIW	Lincoln	27 min
Sep 2, 3:01 PM MDT	Special Weather Statement	RIW	Lincoln	29 min
Sep 2, 3:21 PM MDT	Special Weather Statement	RIW		24 min
Sep 2, 3:30 PM MDT	Special Weather Statement	RIW	Sublette	30 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.