Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 1565
The Storm Prediction Center issued this mesoscale discussion at Aug 19, 2021, 10:55 PM CDT for 7 counties in Kansas; 16 counties in Nebraska. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- Aug 19, 2021, 10:55 PM CDT (03:55 UTC)
- Expired
- Aug 20, 2021, 12:30 AM CDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 23 counties
Graham County, KS, Jewell County, KS, Norton County, KS, Osborne County, KS, Phillips County, KS, Rooks County, KS, Smith County, KS, Adams County, NE, Buffalo County, NE, Custer County, NE, Dawson County, NE, Franklin County, NE, Furnas County, NE, Gosper County, NE, Hall County, NE, Harlan County, NE, Howard County, NE, Kearney County, NE, Nuckolls County, NE, Phelps County, NE, Sherman County, NE, Valley County, NE, Webster County, NE
The radar
The Grand Island radar (KUEX), 69 km from the middle of the area, began a volume at 03:56 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, 3.9 hours before the alert went out and 135 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.
464
ACUS11 KWNS 200356
SWOMCD
SPC MCD 200355
NEZ000-KSZ000-200530-
Mesoscale Discussion 1565
NWS Storm Prediction Center Norman OK
1055 PM CDT Thu Aug 19 2021
Areas affected...central NE...north-central KS
Concerning...Severe potential...Watch unlikely
Valid 200355Z - 200530Z
Probability of Watch Issuance...20 percent
SUMMARY...A new severe thunderstorm watch to the east of tornado
watch #450 is not likely as a gradual lessening of the severe threat
occurs late this evening into the overnight.
DISCUSSION...Radar mosaic shows a squall line from Thedford, NE
arching southwestward to the KS/NE/CO border as of 0345 UTC. A
strong south-southeasterly LLJ will probably continue to strengthen
over the next several hours and gradually veer to southerly. The
Goodland, KS and Dodge City, KS WSR-88D VAD data show 40-50 kt being
sampled around 1 km AGL of the LLJ, indicative of strong low-level
warm air advection. Despite increasing convective inhibition, rich
low-level moisture characterized by surface dewpoints near 70 deg F,
will aid in maintaining a squall line across central NE and far
northern KS late tonight. However, the aforementioned increase in
convective inhibition and sub-optimal orientation of the squall line
with respect to the low- to mid-level shear vector, both suggest a
lessening in potential for severe gusts overnight. Nonetheless,
isolated severe gusts may continue for the next several hours but
the perceived spatial coverage of severe gusts will probably
preclude the need for an additional watch tonight.
..Smith/Thompson.. 08/20/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GID...LBF...GLD...
LAT...LON 41640017 41769897 41209845 40089797 39319825 39199941
39390031 41640017SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 9:27 PM CDT | Mesoscale Discussion | SPC | Cheyenne, Decatur, Norton, Rawlins, Sheridan, Sherman and 1 more | 93 min |
| Aug 20, 3:57 PM CDT | Mesoscale Discussion | SPC | Atchison, Barber, Barton, Brown, Butler, Chase and 36 more | 63 min |
| Aug 20, 4:39 PM CDT | Severe Thunderstorm Watch | SPC | Brown, Clay, Cloud, Dickinson, Geary, Jackson and 12 more | 6 hr |
| Aug 20, 1:51 PM CDT | Mesoscale Discussion | SPC | Burt, Butler, Cass, Cedar, Colfax, Cuming and 22 more | 84 min |
| Aug 20, 3:58 PM CDT | Severe Thunderstorm Watch | SPC | Dakota, Dixon | 6 hr |
Nearby
Mesoscale Discussions in Nebraska, 2021Mesoscale Discussions in Kansas, 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.