Alert archive / Montana / Severe Thunderstorm Watches in 2005

Severe Thunderstorm Watch 308

May 20, 20057 counties in Montana

The Storm Prediction Center issued this severe thunderstorm watch at May 20, 2005, 10:35 PM MDT for 7 counties in Montana. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
May 20, 2005, 10:35 PM MDT (04:35 UTC)
Expired
May 21, 2005, 3:00 AM MDT
In force
4 hr
Issued by
the Storm Prediction Center

Counties Big Horn County, MT, Carter County, MT, Custer County, MT, Fallon County, MT, Powder River County, MT, Rosebud County, MT, Treasure County, MT

The radar

The Billings radar (KBLX), 186 km from the middle of the area, began a volume at 04:39 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.

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 20, 11:17 PM MDTSevere Thunderstorm WarningBYZCuster45 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

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 4.6 hours before the alert went out and 280 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, Glasgow Intl Airport, MT at 00:00Z on 2005-05-21Temperature 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 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Glasgow Intl Airport, MT at 00:00Z on 2005-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -35 square meters per square second.1939587897117Sfc1 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
2659 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
-35 m²/s²
0-3 km storm-relative helicity
88 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 20, 6:47 PM MDTMesoscale DiscussionSPCBig Horn, Carbon, Carter, Custer, Dawson, Fallon and 12 more88 min
May 20, 8:30 PM MDTSevere Thunderstorm WatchSPCDawson, McCone, Prairie, Richland, Wibaux5 hr
May 20, 9:45 PM MDTMesoscale DiscussionSPCBig Horn, Carbon, Custer, Dawson, Golden Valley, McCone and 11 more2 hr

Nearby

Severe Thunderstorm Watches in Montana, 2005Every severe thunderstorm watch in 2005

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.