Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 1682
The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2021, 1:28 PM CDT for 5 counties in Kansas; 19 counties in Nebraska. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 2, 2021, 1:28 PM CDT (18:28 UTC)
- Expired
- Sep 2, 2021, 3:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 24 counties
Decatur County, KS, Graham County, KS, Norton County, KS, Phillips County, KS, Sheridan County, KS, Blaine County, NE, Brown County, NE, Buffalo County, NE, Custer County, NE, Dawson County, NE, Franklin County, NE, Frontier County, NE, Furnas County, NE, Garfield County, NE, Gosper County, NE, Harlan County, NE, Holt County, NE, Kearney County, NE, Loup County, NE, Phelps County, NE, Red Willow County, NE, Rock County, NE, Sherman County, NE, Valley County, NE
The radar
The North Platte radar (KLNX), 125 km from the middle of the area, began a volume at 18:30 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
N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 6.5 hours before the alert went out and 79 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
- 2 J/kg
- Mixed-layer CIN
- -116 J/kg
- Mixed-layer LCL
- 733 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 129 m²/s²
- 0-3 km storm-relative helicity
- 200 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted.
838
ACUS11 KWNS 021828
SWOMCD
SPC MCD 021828
NEZ000-KSZ000-022030-
Mesoscale Discussion 1682
NWS Storm Prediction Center Norman OK
0128 PM CDT Thu Sep 02 2021
Areas affected...much of central Nebraska into northern Kansas
Concerning...Severe potential...Watch possible
Valid 021828Z - 022030Z
Probability of Watch Issuance...60 percent
SUMMARY...Storms are expected to increase in intensity, possibly
becoming severe by 21Z near a surface trough from central Nebraska
into northwest Kansas. A few supercells will be possible, with a
brief tornado or two.
DISCUSSION...An area of rain and thunderstorms is expected to shift
east out of central NE and KS, with heating and destabilization
expected westward toward the surface trough. Convergence along this
trough is currently supporting a low-topped line of convection
across northern NE, but temperatures are currently cool extending
east of this activity.
Visible satellite imagery shows clearing across southwest NE into
western KS, and this will likely support initiation near the surface
trough after about 20-21Z. While surface winds are weak near the
trough, strong boundary-layer flow will persist to the east, along
with 30-40 kt 850 mb winds. Therefore, assuming air mass recovery
late this afternoon, sufficient SRH will support a supercell threat
with cells that form near the trough and proceed east. Objective
analysis currently indicates 0-1 km values over 200 m2/s2. A couple
tornadoes will be possible in a narrow zone where the surface warm
nose and SRH gradient interface. Otherwise, a few severe gusts or
low-end severe hail will be possible.
..Jewell/Grams.. 09/02/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GID...LBF...GLD...
LAT...LON 39709889 39169964 39220045 39610082 40050101 40670089
41470041 42479993 42729982 42899934 42839892 42619865
42019853 40949865 39709889SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 2, 2:11 PM CDT | Mesoscale Discussion | SPC | Dickinson, Geary, Ottawa, Pottawatomie, Riley, Saline and 2 more | 2 hr |
| Sep 2, 4:23 PM CDT | Mesoscale Discussion | SPC | Barton, Clark, Clay, Cloud, Dickinson, Edwards and 16 more | 97 min |
| Sep 2, 5:27 PM CDT | Tornado Watch | SPC | Barton, Clay, Cloud, Dickinson, Ellis, Ellsworth and 27 more | 5 hr |
| Sep 1, 9:20 PM CDT | Mesoscale Discussion | SPC | Box Butte, Cherry, Dawes, Garden, Morrill, Scotts Bluff and 2 more | 85 min |
| Sep 1, 11:36 PM CDT | Mesoscale Discussion | SPC | Arthur, Cherry, Garden, Grant, Hooker, Sheridan | 84 min |
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.