Alert archive / Wyoming / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 56, NWS Riverton, WY

August 19, 2007Fremont County, Sublette County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Aug 19, 2007, 2:23 PM MDT for Fremont County, Sublette County, Wyoming. It was in force for 52 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 19, 2007, 2:23 PM MDT (20:23 UTC)
Expired
Aug 19, 2007, 3:15 PM MDT
In force
52 min
Issued by
NWS Riverton, WY
Area
Counties, with a storm outline in the text

Counties Fremont County, WY, Sublette County, WY

The radar

The Riverton/Lander radar (KRIW), 67 km from the middle of the area, began a volume at 20:24 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 19, 1:36 PM MDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 8.4 hours before the alert went out and 73 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-pSkew-T log-p diagram, Riverton, WY at 12:00Z on 2007-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Riverton, WY at 12:00Z on 2007-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 133 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
2424 m above ground
0-6 km bulk shear
57 kt
0-1 km storm-relative helicity
133 m²/s²
0-3 km storm-relative helicity
108 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 19, 11:53 AM MDT, 2 hours 30 minutes earlier.

Area forecast discussion, Aug 19, 11:53 AM MDT, 2 hours 30 minutes before
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Hazardous weather outlook, Aug 19, 1:35 PM MDT, 48 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RIVERTON WY
135 PM MDT SUN AUG 19 2007

WYZ001>020-022>030-201300-
ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST-
BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS-
EAST SWEETWATER COUNTY-FLAMING GORGE-
GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS-
NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN-
NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS-
ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES-
SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN-
SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY-
TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN-
UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN-
WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST-
YELLOWSTONE NATIONAL PARK-
135 PM MDT SUN AUG 19 2007

...RED FLAG WARNING IN EFFECT SUNDAY 2 PM THROUGH 9 PM FOR
PORTIONS OF CENTRAL AND SOUTHERN WYOMING...

...SEVERE THUNDERSTORM WATCH 617 IS IN EFFECT UNTIL 8 PM FOR MUCH OF
WESTERN AND CENTRAL WYOMING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING.

.DAY ONE...THIS AFTERNOON AND TONIGHT

STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND
TONIGHT...MAINLY BETWEEN 3 PM AND 9 PM.  THE MOST LIKELY AREAS TO
HAVE SEVERE THUNDERSTORMS WILL BE ACROSS WESTERN AND NORTHERN
WYOMING.  THE MAIN HAZARDS WILL BE LARGE HAIL AND DAMAGING WINDS.
THE ONLY AREAS NOT INCLUDED IN SEVERE THUNDERSTORM WATCH 617 ARE
NATRONA AND JOHNSON COUNTIES.

SOUTHWEST WIND WILL CONTINUE TO INCREASE THIS MORNING AND BECOME
STRONG LATER THIS AFTERNOON...AHEAD OF AN APPROACHING STORM SYSTEM.
THIS SOUTHWEST WIND WILL BEGIN TO USHER IN DRIER AIR INTO THE
REGION. THESE STRONG WINDS COMBINED WITH LOW HUMIDITIES WILL CREATE
RED FLAG CONDITIONS IN PORTIONS OF CENTRAL AND SOUTHERN WYOMING THIS
AFTERNOON AND EVENING. A STRONG COLD FRONT WILL MOVE ACROSS WEST
AND CENTRAL WYOMING THIS EVENING.  WEST WIND AT 20 TO 30 MPH WITH
GUSTS TO 40 MPH WILL ACCOMPANY THE FRONT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS...PLEASE REPORT ANY WIND GUSTS OVER 40 MPH AND HAIL SIZES
THIS AFTERNOON AND TONIGHT.

TEAM RIVERTON

In the hours before

Special weather statement, Aug 19, 12:58 PM MDT, 1 hour 25 minutes before
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Special weather statement, Aug 19, 1:24 PM MDT, 59 minutes before
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Special weather statement, Aug 19, 1:29 PM MDT, 54 minutes before
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Special weather statement, Aug 19, 1:40 PM MDT, 43 minutes before
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Special weather statement, Aug 19, 1:54 PM MDT, 29 minutes before
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Special weather statement, Aug 19, 2:10 PM MDT, 13 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 19, 2:54 AM MDTRed Flag WarningRIWFremont, Lincoln, Natrona, Sublette, Sweetwater, Uinta17 hr
Aug 19, 2:31 PM MDTSevere Thunderstorm WarningRIWTeton59 min
Aug 19, 2:58 PM MDTSevere Thunderstorm WarningRIWFremont62 min
Aug 19, 3:44 PM MDTSevere Thunderstorm WarningRIWFremont, Sublette61 min
Aug 19, 4:19 PM MDTRed Flag WarningRIWFremont, Lincoln, Natrona, Sublette, Sweetwater, Uinta28 hr
Aug 19, 4:45 PM MDTSevere Thunderstorm WarningRIWFremont60 min
Aug 19, 5:15 PM MDTSevere Thunderstorm WarningRIWFremont37 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2007Every severe thunderstorm warning in 2007

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.