Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 1564
The Storm Prediction Center issued this mesoscale discussion at Aug 19, 2021, 8:27 PM MDT for Phillips County, Yuma County, Colorado; 7 counties in Kansas; 19 counties in Nebraska. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Aug 19, 2021, 8:27 PM MDT (02:27 UTC)
- Expired
- Aug 19, 2021, 10:00 PM MDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 450
All 28 counties
Phillips County, CO, Yuma County, CO, Cheyenne County, KS, Decatur County, KS, Norton County, KS, Rawlins County, KS, Sheridan County, KS, Sherman County, KS, Thomas County, KS, Blaine County, NE, Chase County, NE, Custer County, NE, Dawson County, NE, Dundy County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Keith County, NE, Lincoln County, NE, Logan County, NE, McPherson County, NE, Perkins County, NE, Phelps County, NE, Red Willow County, NE, Thomas County, NE
The radar
The Goodland radar (KGLD), 101 km from the middle of the area, began a volume at 02:31 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
N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 2.5 hours before the alert went out and 117 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.
- Mixed-layer CAPE
- 1368 J/kg
- Mixed-layer CIN
- -6 J/kg
- Mixed-layer LCL
- 1220 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 145 m²/s²
- 0-3 km storm-relative helicity
- 208 m²/s²
- Significant tornado parameter
- 1.1
- Supercell composite
- 10.2
The text
As transmitted.
265
ACUS11 KWNS 200227
SWOMCD
SPC MCD 200227
NEZ000-KSZ000-COZ000-200400-
Mesoscale Discussion 1564
NWS Storm Prediction Center Norman OK
0927 PM CDT Thu Aug 19 2021
Areas affected...Western Nebraska...Northeast Colorado...and
Northwest Kansas
Concerning...Tornado Watch 450...
Valid 200227Z - 200400Z
The severe weather threat for Tornado Watch 450 continues.
SUMMARY...Upscale growth of ongoing convective activity will support
the potential for damaging winds, severe hail, and perhaps a tornado
or two across WW 450.
DISCUSSION...Storms that have developed across the region are now
beginning to merge into a multicell cluster, with the strongest
cells located in far northeast Colorado and southwest Nebraska. The
environment, characterized by MLCAPE of 1500-2000 J/kg and 40-50 kt
of effective bulk shear, continues to support supercell/embedded
supercell structures, with persistent mid-level rotation and brief
low-level rotation noted. As such, storms have mainly produced large
hail, including a report of 2 inch hail in Chase county, Nebraska.
The trend toward upscale growth is expected to continue for the next
few hours as the low-level jet continues to strengthen. The primary
severe threat may transition to damaging winds, as evidenced by a 71
mph gust measured at Imperial, Nebraska, at 0219 UTC. Large hail
will remain possible with the most intense embedded cells,
particularly along the southern flank of the convective line where
renewed convective development is occurring and will remain
possible. A tornado or two also remains possible given a notable
increase in low-level shear to near 35-40 kt and enlarged hodographs
evident in regional VAD wind profiles.
..Karstens.. 08/20/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GID...LBF...GLD...BOU...
LAT...LON 39120094 39120206 40030266 40120267 40640251 41210173
42140117 42300017 41669929 39979945 39290025 39120072
39120076 39120078 39120094SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 9:55 PM MDT | Mesoscale Discussion | SPC | Graham, Jewell, Norton, Osborne, Phillips, Rooks and 1 more | 95 min |
| Aug 20, 2:57 PM MDT | Mesoscale Discussion | SPC | Atchison, Barber, Barton, Brown, Butler, Chase and 36 more | 63 min |
| Aug 20, 3:39 PM MDT | Severe Thunderstorm Watch | SPC | Brown, Clay, Cloud, Dickinson, Geary, Jackson and 12 more | 6 hr |
| Aug 20, 12:51 PM MDT | Mesoscale Discussion | SPC | Burt, Butler, Cass, Cedar, Colfax, Cuming and 22 more | 84 min |
| Aug 20, 2:58 PM MDT | Severe Thunderstorm Watch | SPC | Dakota, Dixon | 6 hr |
Nearby
Mesoscale Discussions in Nebraska, 2021Mesoscale Discussions in Kansas, 2021Mesoscale Discussions in Colorado, 2021Every 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.