Alert archive / Montana / Mesoscale Discussions in 2020

Mesoscale Discussion 653

May 20, 20204 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at May 20, 2020, 9:10 PM MDT for 4 counties in Montana. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued
May 20, 2020, 9:10 PM MDT (03:10 UTC)
Expired
May 20, 2020, 10:45 PM MDT
In force
95 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 197

Counties Daniels County, MT, Phillips County, MT, Roosevelt County, MT, Valley County, MT

The radar

The Glasgow radar (KGGW), 29 km from the middle of the area, began a volume at 03:11 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

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 3.2 hours before the alert went out and 27 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 2020-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 975 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, Glasgow Intl Airport, MT at 00:00Z on 2020-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 2 square meters per square second.19395878Sfc1 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
975 J/kg
Mixed-layer CIN
-43 J/kg
Mixed-layer LCL
1692 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
2 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.4

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 20, 6:27 PM MDTMesoscale DiscussionSPCBig Horn, Blaine, Carbon, Carter, Custer, Daniels and 19 more93 min

Nearby

Mesoscale Discussions in Montana, 2020Every mesoscale discussion in 2020

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.