Alert archive / Nebraska / Mesoscale Discussions in 2019

Mesoscale Discussion 1813

August 20, 20194 counties in Nebraska; Goshen County, Laramie County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2019, 2:30 PM MDT for 4 counties in Nebraska; Goshen County, Laramie County, Wyoming. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued
Aug 20, 2019, 2:30 PM MDT (20:30 UTC)
Expired
Aug 20, 2019, 3:30 PM MDT
In force
60 min
Issued by
the Storm Prediction Center
Chance of a watch
60%

Counties Banner County, NE, Kimball County, NE, Scotts Bluff County, NE, Sioux County, NE, Goshen County, WY, Laramie County, WY

The radar

The Cheyenne radar (KCYS), 112 km from the middle of the area, began a volume at 20:34 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.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 8.5 hours before the alert went out and 249 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, Rapid City, SD at 12:00Z on 2019-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 307 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, Rapid City, SD at 12:00Z on 2019-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 32 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
307 J/kg
Mixed-layer CIN
-354 J/kg
Mixed-layer LCL
2280 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
32 m²/s²
0-3 km storm-relative helicity
322 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

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
Aug 19, 10:05 PM MDTMesoscale DiscussionSPCBurt, Dakota, Thurston115 min
Aug 20, 3:03 PM MDTSevere Thunderstorm WatchSPCBanner, Box Butte, Cheyenne, Dawes, Kimball, Morrill and 2 more8 hr

Nearby

Mesoscale Discussions in Nebraska, 2019Mesoscale Discussions in Wyoming, 2019Every mesoscale discussion in 2019

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.