Alert archive / Montana / Mesoscale Discussions in 2018

Mesoscale Discussion 812

June 21, 20187 counties in Idaho; 19 counties in Montana; 4 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2018, 2:28 PM MDT for 7 counties in Idaho; 19 counties in Montana; 4 counties in Wyoming. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued
Jun 21, 2018, 2:28 PM MDT (20:28 UTC)
Expired
Jun 21, 2018, 4:00 PM MDT
In force
92 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 30 counties

Bonneville County, ID, Butte County, ID, Clark County, ID, Fremont County, ID, Jefferson County, ID, Madison County, ID, Teton County, ID, Big Horn County, MT, Broadwater County, MT, Carbon County, MT, Cascade County, MT, Chouteau County, MT, Fergus County, MT, Gallatin County, MT, Golden Valley County, MT, Jefferson County, MT, Judith Basin County, MT, Madison County, MT, Meagher County, MT, Musselshell County, MT, Park County, MT, Petroleum County, MT, Stillwater County, MT, Sweet Grass County, MT, Wheatland County, MT, Yellowstone County, MT, Big Horn County, WY, Hot Springs County, WY, Park County, WY, Teton County, WY

The radar

The Billings radar (KBLX), 133 km from the middle of the area, began a volume at 20:31 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

Great_falls, MT (KTFX), launched 12:00Z, 8.5 hours before the alert went out and 213 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, Great_falls, MT at 12:00Z on 2018-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 89 joules per kilogram.LCLLFCEL10008507005003002001001 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, Great_falls, MT at 12:00Z on 2018-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 37 square meters per square second.1939Sfc1 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
89 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
1652 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
37 m²/s²
0-3 km storm-relative helicity
30 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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Nearby

Mesoscale Discussions in Montana, 2018Mesoscale Discussions in Idaho, 2018Mesoscale Discussions in Wyoming, 2018Every mesoscale discussion in 2018

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.