Alert archive / Nebraska / Mesoscale Discussions in 2018
Mesoscale Discussion 1013
The Storm Prediction Center issued this mesoscale discussion at Jul 4, 2018, 5:35 PM CDT for Plymouth County, Iowa; 21 counties in Nebraska; 4 counties in South Dakota. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Jul 4, 2018, 5:35 PM CDT (22:35 UTC)
- Expired
- Jul 4, 2018, 7:30 PM CDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 26 counties
Plymouth County, IA, Antelope County, NE, Blaine County, NE, Boyd County, NE, Brown County, NE, Cedar County, NE, Custer County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Holt County, NE, Knox County, NE, Logan County, NE, Loup County, NE, Madison County, NE, Pierce County, NE, Rock County, NE, Thomas County, NE, Thurston County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Union County, SD, Yankton County, SD
The radar
The North Platte radar (KLNX), 172 km from the middle of the area, began a volume at 22:35 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
Omaha, NE (KOAX), launched 12:00Z, 10.6 hours before the alert went out and 203 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
- 762 J/kg
- Mixed-layer CIN
- -257 J/kg
- Mixed-layer LCL
- 1648 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- -53 m²/s²
- 0-3 km storm-relative helicity
- 25 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
460
ACUS11 KWNS 042235
SWOMCD
SPC MCD 042235
IAZ000-NEZ000-SDZ000-050030-
Mesoscale Discussion 1013
NWS Storm Prediction Center Norman OK
0535 PM CDT Wed Jul 04 2018
Areas affected...Portions of central/eastern NE...far western
IA...and extreme southeastern SD
Concerning...Severe potential...Watch possible
Valid 042235Z - 050030Z
Probability of Watch Issuance...40 percent
SUMMARY...An isolated large hail threat should continue this
evening, with some potential for strong/damaging winds possible if
thunderstorms can grow upscale. WW issuance remains possible.
DISCUSSION...Scattered thunderstorms have formed over the past
couple of hours along a surface boundary across northeastern NE.
Large-scale lift remains nebulous across this region, although a
small mid-level perturbation possibly related to prior convection
may be aiding convective maintenance. A very moist and unstable
airmass resides to the south of the boundary, with MLCAPE around
2000-3000 J/kg per 22Z RAP mesoanalysis estimates. Modest low and
mid-level wind fields have generally limited greater storm
organization thus far, with the better flow mostly displaced to the
north of the surface boundary. Still, around 30-35 kt of effective
bulk shear may be enough to support marginal supercell structures as
convection forms and then lifts north of the boundary. Isolated
large hail should be the main threat with ongoing activity, and a
brief tornado is also possible as storms cross the front. If
additional convection can form along the front in central NE and
then develop eastward as a small bowing cluster, as the past several
runs of the HRRR suggest, then perhaps a greater strong/damaging
wind threat would exist. For now, Severe Thunderstorm Watch issuance
remains possible, and mainly dependent on additional signs of
development in central NE.
..Gleason/Grams.. 07/04/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...OAX...GID...LBF...
LAT...LON 41910056 42759956 43019841 43019709 42969601 42569594
42239622 41859779 41349930 41330020 41490060 41910056SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 4, 9:56 AM CDT | Mesoscale Discussion | SPC | Allamakee, Chickasaw, Howard, Mitchell, Winneshiek | 2 hr |
| Jul 4, 10:27 AM CDT | Mesoscale Discussion | SPC | Audubon, Black Hawk, Boone, Bremer, Buena Vista, Butler and 35 more | 2 hr |
| Jul 4, 2:01 PM CDT | Mesoscale Discussion | SPC | Monona, Plymouth, Woodbury | 119 min |
| Jul 3, 7:36 PM CDT | Mesoscale Discussion | SPC | Arthur, Banner, Chase, Cheyenne, Deuel, Dundy and 11 more | 54 min |
| Jul 4, 2:51 PM CDT | Mesoscale Discussion | SPC | Arthur, Banner, Box Butte, Cheyenne, Deuel, Garden and 7 more | 54 min |
| Jul 3, 9:38 PM CDT | Mesoscale Discussion | SPC | Bennett, Butte, Custer, Fall River, Haakon, Harding and 7 more | 2 hr |
| Jul 3, 10:38 PM CDT | Mesoscale Discussion | SPC | Brown, Campbell, Clark, Corson, Day, Dewey and 14 more | 97 min |
| Jul 3, 11:02 PM CDT | Severe Thunderstorm Watch | SPC | Brown, Campbell, Clark, Corson, Day, Dewey and 13 more | 6 hr |
| Jul 4, 3:14 AM CDT | Mesoscale Discussion | SPC | Beadle, Brown, Clark, Codington, Day, Edmunds and 14 more | 91 min |
Nearby
Mesoscale Discussions in Nebraska, 2018Mesoscale Discussions in South Dakota, 2018Mesoscale Discussions in Iowa, 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.