Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 475

May 2, 20218 counties in Colorado; 10 counties in Kansas; 11 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at May 2, 2021, 2:45 PM MDT for 8 counties in Colorado; 10 counties in Kansas; 11 counties in Nebraska. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: May 2, 2021, 2:45 PM MDT (20:45 UTC)
Expired: May 2, 2021, 4:15 PM MDT
In force: 90 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 124

All 29 counties

Cheyenne County, CO, Crowley County, CO, Kiowa County, CO, Kit Carson County, CO, Lincoln County, CO, Phillips County, CO, Sedgwick County, CO, Yuma County, CO, Cheyenne County, KS, Decatur County, KS, Greeley County, KS, Logan County, KS, Rawlins County, KS, Sheridan County, KS, Sherman County, KS, Thomas County, KS, Wallace County, KS, Wichita County, KS, Arthur County, NE, Chase County, NE, Deuel County, NE, Dundy County, NE, Frontier County, NE, Hayes County, NE, Hitchcock County, NE, Keith County, NE, Lincoln County, NE, Perkins County, NE, Red Willow County, NE

The radar

The Goodland radar (KGLD), 61 km from the middle of the area, began a volume at 20:48 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.

Severe Thunderstorm Watch 126May 2, 4:40 PM MDT

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 8.8 hours before the alert went out and 102 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1976 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: -89 m²/s²
0-3 km storm-relative helicity: 10 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

710 
ACUS11 KWNS 022046
SWOMCD
SPC MCD 022045 
KSZ000-NEZ000-COZ000-022215-

Mesoscale Discussion 0475
NWS Storm Prediction Center Norman OK
0345 PM CDT Sun May 02 2021

Areas affected...Eastern CO...northwest KS...southwest NE

Concerning...Severe Thunderstorm Watch 124...

Valid 022045Z - 022215Z

The severe weather threat for Severe Thunderstorm Watch 124
continues.

SUMMARY...While the severe threat through 23Z should remain rather
isolated over eastern CO and southwest NE, a substantial increase is
expected this evening centered on northwest KS. A downstream severe
thunderstorm watch will likely be needed.

DISCUSSION...Near-term severe threat is expected to remain most
prominent with a southeast-moving supercell that is currently east
of Pueblo. This cell should propagate more east-southeast over the
next couple hours across southeast CO with a risk for mainly severe
wind and some hail. Convection farther northeast across northeast CO
into western NE has generally remained sub-severe with the most
prominent recent wind gust of 45 kt at AKO at 2010Z. This activity
should largely spread across southwest NE with a threat for strong
to isolated severe wind and marginally severe hail.

Recent HRRR runs along with the 18Z NAM-Nest have trended towards
the indication of a separate corridor of thunderstorm development
across northwest KS. This appears to be in response to strengthening
low-level convergence along the boundary, especially from 23-00Z, as
it impinges on the northwest periphery of MLCAPE near 1000 J/kg.
Initial updrafts will pose a severe hail threat before upscale
growth yields a substantial severe wind threat around 01-02Z given
the steep lapse rate environment.

..Grams.. 05/02/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...GID...LBF...DDC...GLD...PUB...BOU...

LAT...LON   40430307 41140233 41720164 41610120 41240063 40890039
            40550026 39980008 39170018 38490133 37970227 37950347
            38260404 38640424 39220343 39840302 40430307

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 2, 10:14 AM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Boulder, Broomfield, Clear Creek, Denver and 7 more	2 hr
May 2, 11:45 AM MDT	Severe Thunderstorm Watch	SPC	Adams, Arapahoe, Bent, Cheyenne, Crowley, Douglas and 10 more	7 hr
May 2, 1:15 PM MDT	Mesoscale Discussion	SPC	Cheyenne, Elbert, El Paso, Kit Carson, Lincoln, Morgan and 3 more	90 min
May 2, 4:12 PM MDT	Mesoscale Discussion	SPC	Baca, Bent, Prowers	93 min
May 2, 4:26 PM MDT	Mesoscale Discussion	SPC	Barton, Cheyenne, Decatur, Edwards, Ellis, Ellsworth and 32 more	64 min
May 2, 4:41 PM MDT	Severe Thunderstorm Watch	SPC	Barton, Cheyenne, Decatur, Edwards, Ellis, Ellsworth and 34 more	6 hr

Nearby

Mesoscale Discussions in Nebraska, 2021 Mesoscale Discussions in Kansas, 2021 Mesoscale Discussions in Colorado, 2021 Every mesoscale discussion in 2021

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.