Alert archive / Wyoming / Severe Thunderstorm Watches in 2008

Severe Thunderstorm Watch 660

July 6, 20089 counties in Montana; 7 counties in South Dakota; 11 counties in Wyoming

The Storm Prediction Center issued this severe thunderstorm watch at Jul 6, 2008, 1:32 PM MDT for 9 counties in Montana; 7 counties in South Dakota; 11 counties in Wyoming. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Jul 6, 2008, 1:32 PM MDT (19:32 UTC)
Expired
Jul 6, 2008, 9:00 PM MDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 27 counties

Big Horn County, MT, Carbon County, MT, Carter County, MT, Custer County, MT, Fallon County, MT, Powder River County, MT, Rosebud County, MT, Treasure County, MT, Yellowstone County, MT, Butte County, SD, Custer County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Pennington County, SD, Perkins County, SD, Big Horn County, WY, Campbell County, WY, Crook County, WY, Fremont County, WY, Hot Springs County, WY, Johnson County, WY, Natrona County, WY, Park County, WY, Sheridan County, WY, Washakie County, WY, Weston County, WY

The radar

The Billings radar (KBLX), 183 km from the middle of the area, began a volume at 19:34 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
50%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

42 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jul 6, 1:38 PM MDTSevere Thunderstorm WarningRIWJohnson23 min
Jul 6, 1:45 PM MDTSevere Thunderstorm WarningBYZSheridan60 min
Jul 6, 1:46 PM MDTSevere Thunderstorm WarningBYZCuster, Powder River, Rosebud59 min
Jul 6, 2:08 PM MDTSevere Thunderstorm WarningRIWJohnson52 min
Jul 6, 2:20 PM MDTFlash Flood WarningBYZBig Horn, Custer, Powder River, Rosebud, Treasure3 hr
Jul 6, 2:30 PM MDTSevere Thunderstorm WarningRIWFremont, Hot Springs45 min
Jul 6, 2:36 PM MDTSevere Thunderstorm WarningBYZSheridan43 min
Jul 6, 2:44 PM MDTSevere Thunderstorm WarningBYZCuster, Powder River, Rosebud45 min
Jul 6, 2:44 PM MDTSevere Thunderstorm WarningRIWJohnson, Natrona46 min
Jul 6, 2:47 PM MDTFlash Flood WarningRIWJohnson, Natrona118 min
Jul 6, 2:59 PM MDTSevere Thunderstorm WarningRIWFremont, Hot Springs, Washakie46 min
Jul 6, 2:59 PM MDTSevere Thunderstorm WarningRIWJohnson46 min
Jul 6, 3:06 PM MDTSevere Thunderstorm WarningRIWHot Springs39 min
Jul 6, 3:19 PM MDTSevere Thunderstorm WarningRIWNatrona26 min
Jul 6, 3:30 PM MDTSevere Thunderstorm WarningBYZPowder River, Rosebud60 min
Jul 6, 3:41 PM MDTSevere Thunderstorm WarningRIWFremont, Natrona27 min
Jul 6, 3:47 PM MDTSevere Thunderstorm WarningRIWWashakie43 min
Jul 6, 3:49 PM MDTSevere Thunderstorm WarningRIWJohnson56 min
Jul 6, 3:56 PM MDTSevere Thunderstorm WarningRIWJohnson, Natrona64 min
Jul 6, 4:11 PM MDTSevere Thunderstorm WarningRIWFremont49 min
Jul 6, 4:21 PM MDTSevere Thunderstorm WarningRIWNatrona54 min
Jul 6, 4:28 PM MDTSevere Thunderstorm WarningBYZCuster, Powder River, Rosebud62 min
Jul 6, 4:33 PM MDTSevere Thunderstorm WarningUNRLawrence, Pennington51 min
Jul 6, 4:36 PM MDTSevere Thunderstorm WarningUNRCampbell54 min
Jul 6, 4:47 PM MDTSevere Thunderstorm WarningRIWFremont43 min
Jul 6, 4:59 PM MDTSevere Thunderstorm WarningRIWFremont46 min
Jul 6, 5:04 PM MDTSevere Thunderstorm WarningRIWNatrona41 min
Jul 6, 5:13 PM MDTSevere Thunderstorm WarningRIWFremont, Natrona47 min
Jul 6, 5:27 PM MDTSevere Thunderstorm WarningUNRCampbell30 min
Jul 6, 5:35 PM MDTSevere Thunderstorm WarningBYZCarter55 min
Jul 6, 6:24 PM MDTSevere Thunderstorm WarningBYZCarter48 min
Jul 6, 6:24 PM MDTSevere Thunderstorm WarningUNRCampbell, Weston35 min
Jul 6, 6:32 PM MDTSevere Thunderstorm WarningUNRCuster58 min
Jul 6, 6:40 PM MDTSevere Thunderstorm WarningBYZBig Horn, Powder River, Rosebud65 min
Jul 6, 6:55 PM MDTSevere Thunderstorm WarningUNRButte, Harding65 min
Jul 6, 7:12 PM MDTSevere Thunderstorm WarningUNRLawrence, Pennington63 min
Jul 6, 7:37 PM MDTSevere Thunderstorm WarningUNRButte, Harding53 min
Jul 6, 7:45 PM MDTSevere Thunderstorm WarningBYZRosebud32 min
Jul 6, 7:46 PM MDTFlash Flood WarningBYZPowder River, Rosebud6 hr
Jul 6, 7:52 PM MDTSevere Thunderstorm WarningBYZSheridan53 min
Jul 6, 8:14 PM MDTSevere Thunderstorm WarningUNRPerkins37 min
Jul 6, 8:33 PM MDTSevere Thunderstorm WarningUNRCuster, Lawrence, Pennington57 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 7.5 hours before the alert went out and 239 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 2008-07-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 544 joules per kilogram.LCLLFCEL10008507005003002001001 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 2008-07-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 41 square meters per square second.193958Sfc1 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
544 J/kg
Mixed-layer CIN
-173 J/kg
Mixed-layer LCL
1453 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
41 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 6, 1:14 PM MDTMesoscale DiscussionSPCBig Horn, Carbon, Carter, Powder River61 min
Jul 5, 7:15 PM MDTMesoscale DiscussionSPCBarnes, Cass, Cavalier, Dickey, Eddy, Foster and 16 more60 min
Jul 6, 1:36 PM MDTMesoscale DiscussionSPCClay, Lincoln, Turner, Union, Yankton114 min
Jul 6, 2:05 PM MDTSevere Thunderstorm WatchSPCClay, Union7 hr

Nearby

Severe Thunderstorm Watches in Wyoming, 2008Severe Thunderstorm Watches in Montana, 2008Severe Thunderstorm Watches in South Dakota, 2008Every severe thunderstorm watch in 2008

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.