Alert archive / Wyoming / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 61, NWS Riverton, WY

August 4, 2009Johnson County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Aug 4, 2009, 5:00 PM MDT for Johnson County, Wyoming. It was in force for 15 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: Aug 4, 2009, 5:00 PM MDT (23:00 UTC)
Expired: Aug 4, 2009, 5:15 PM MDT
In force: 15 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon

County Johnson County, WY

The radar

The Riverton/Lander radar (KRIW), 187 km from the middle of the area, began a volume at 23:03 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, 11.0 hours before the alert went out and 182 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: 2745 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 132 m²/s²
0-3 km storm-relative helicity: 262 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 Riverton, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 4, 3:17 PM MDT, 1 hour 43 minutes earlier.

Area forecast discussion, Aug 4, 3:17 PM MDT, 1 hour 43 minutes before

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Hazardous weather outlook, Aug 4, 3:45 PM MDT, 1 hour 15 minutes before

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In the hours before

Special weather statement, Aug 4, 2:12 PM MDT, 2 hours 48 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
212 PM MDT TUE AUG 4 2009

WYZ004-042115-
NORTH BIG HORN BASIN-
212 PM MDT TUE AUG 4 2009

...SIGNIFICANT WEATHER ADVISORY FOR BIG HORN AND PARK COUNTIES UNTIL
315 PM MDT...

AT 208 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR HWY 14/16/20 MILE MARKER 80...OR 22 MILES
SOUTHEAST OF POWELL...MOVING SOUTHEAST AT 30 MPH.

PENNY SIZE HAIL...AND WINDS AROUND 50 MPH ARE POSSIBLE WITH THIS
STORM.

THIS STORM WILL BE...
  NEAR BURLINGTON BY 220 PM MDT.
  NEAR OTTO BY 235 PM MDT.

RESIDENTS IN SOUTHWEST BIG HORN COUNTY AND SOUTHEAST PARK COUNTY
SHOULD MONITOR THE WEATHER SITUATION CLOSELY. LISTEN FOR POSSIBLE
WARNINGS AND BE PREPARED TO TAKE APPROPRIATE ACTION SHOULD SEVERE
WEATHER THREATEN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOVE INDOORS IMMEDIATELY AS THIS STORM APPROACHES YOUR LOCATION. THIS
IS A POTENTIALLY DANGEROUS STORM. IF YOU ARE IN ITS PATH...YOU SHOULD
BE PREPARED FOR GUSTY WINDS...HAIL...AND DEADLY CLOUD TO GROUND
LIGHTNING. IF A STURDY STRUCTURE IS NOT AVAILABLE...SEEK SHELTER IN A
VEHICLE WITH THE WINDOWS UP.

&&

REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.

LAT...LON 4435 10772 4418 10793 4422 10847 4437 10878
      4463 10855
TIME...MOT...LOC 2010Z 300DEG 28KT 4445 10855

MURRELL

Special weather statement, Aug 4, 2:25 PM MDT, 2 hours 35 minutes before

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Special weather statement, Aug 4, 2:36 PM MDT, 2 hours 24 minutes before

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Special weather statement, Aug 4, 3:05 PM MDT, 1 hour 55 minutes before

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Special weather statement, Aug 4, 3:53 PM MDT, 1 hour 7 minutes before

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Special weather statement, Aug 4, 4:10 PM MDT, 50 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
Aug 3, 8:01 PM MDT	Special Weather Statement	RIW	Fremont	59 min
Aug 4, 1:31 PM MDT	Special Weather Statement	RIW		44 min
Aug 4, 2:12 PM MDT	Special Weather Statement	RIW	Big Horn	63 min
Aug 4, 2:25 PM MDT	Special Weather Statement	RIW	Big Horn	65 min
Aug 4, 2:36 PM MDT	Special Weather Statement	RIW		39 min
Aug 4, 3:05 PM MDT	Special Weather Statement	RIW	Teton	40 min
Aug 4, 3:53 PM MDT	Special Weather Statement	RIW	Johnson	52 min
Aug 4, 5:40 PM MDT	Special Weather Statement	RIW	Fremont	35 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2009 Every severe thunderstorm warning in 2009

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.