Alert archive / South Dakota / Mesoscale Discussions in 2018

Mesoscale Discussion 1078

July 18, 201811 counties in Nebraska; 30 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2018, 5:16 PM CDT for 11 counties in Nebraska; 30 counties in South Dakota. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued
Jul 18, 2018, 5:16 PM CDT (22:16 UTC)
Expired
Jul 18, 2018, 7:15 PM CDT
In force
119 min
Issued by
the Storm Prediction Center
All 41 counties

Antelope County, NE, Boyd County, NE, Cedar County, NE, Dixon County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Rock County, NE, Wayne County, NE, Aurora County, SD, Bennett County, SD, Bon Homme County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Davison County, SD, Dewey County, SD, Douglas County, SD, Gregory County, SD, Haakon County, SD, Hand County, SD, Hanson County, SD, Hughes County, SD, Hutchinson County, SD, Hyde County, SD, Jackson County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Meade County, SD, Mellette County, SD, Pennington County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Yankton County, SD, Ziebach County, SD

The radar

The North Platte radar (KLNX), 203 km from the middle of the area, began a volume at 22:18 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

Aberdeen, SD (KABR), launched 12:00Z, 10.3 hours before the alert went out and 169 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, Aberdeen, SD at 12:00Z on 2018-07-18Temperature 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, Aberdeen, SD at 12:00Z on 2018-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -90 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1815 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
-90 m²/s²
0-3 km storm-relative helicity
-9 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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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 17, 11:04 PM CDTMesoscale DiscussionSPCBox Butte, Dawes, Scotts Bluff, Sheridan, Sioux86 min
Jul 18, 1:57 AM CDTMesoscale DiscussionSPCArthur, Garden, Grant, Hooker, Keith, McPherson and 2 more2 hr
Jul 18, 1:39 PM CDTMesoscale DiscussionSPCBoyd, Brown, Holt, Keya Paha, Rock2 hr
Jul 18, 3:43 PM CDTTornado WatchSPCAntelope, Boyd, Brown, Cedar, Garfield, Holt and 5 more7 hr
Jul 18, 4:59 PM CDTMesoscale DiscussionSPCBlaine, Brown, Buffalo, Cherry, Custer, Dawson and 15 more91 min
Jul 18, 6:14 PM CDTSevere Thunderstorm WatchSPCAdams, Antelope, Blaine, Boone, Boyd, Brown and 52 more7 hr

Nearby

Mesoscale Discussions in South Dakota, 2018Mesoscale Discussions in Nebraska, 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.