Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 1213
The Storm Prediction Center issued this mesoscale discussion at Jul 9, 2021, 1:38 PM MDT for 4 states. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Jul 9, 2021, 1:38 PM MDT (19:38 UTC)
- Expired
- Jul 9, 2021, 3:15 PM MDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 36 counties
Adams County, CO, Logan County, CO, Morgan County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO, Yuma County, CO, Cheyenne County, KS, Rawlins County, KS, Sherman County, KS, Arthur County, NE, Banner County, NE, Box Butte County, NE, Chase County, NE, Cheyenne County, NE, Deuel County, NE, Dundy County, NE, Garden County, NE, Grant County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Keith County, NE, Kimball County, NE, Lincoln County, NE, McPherson County, NE, Morrill County, NE, Perkins County, NE, Red Willow County, NE, Scotts Bluff County, NE, Sheridan County, NE, Sioux County, NE, Goshen County, WY, Laramie County, WY, Platte County, WY
The radar
The Cheyenne radar (KCYS), 140 km from the middle of the area, began a volume at 19:39 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
Denver, CO (KDNR), launched 12:00Z, 7.6 hours before the alert went out and 167 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
- 5 J/kg
- Mixed-layer CIN
- -346 J/kg
- Mixed-layer LCL
- 3383 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 70 m²/s²
- 0-3 km storm-relative helicity
- 50 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
636
ACUS11 KWNS 091939
SWOMCD
SPC MCD 091938
NEZ000-KSZ000-COZ000-WYZ000-092115-
Mesoscale Discussion 1213
NWS Storm Prediction Center Norman OK
0238 PM CDT Fri Jul 09 2021
Areas affected...Southeastern Wyoming...Northeastern
Colorado...Western Nebraska...and Far Northwestern Kansas
Concerning...Severe potential...Watch likely
Valid 091938Z - 092115Z
Probability of Watch Issuance...80 percent
SUMMARY...Thunderstorms are initiating over the high terrain of
southeastern Wyoming. The storms are expected to intensify as they
move eastward into a more favorable environment. A severe
thunderstorm watch is likely in the next couple of hours.
DISCUSSION...Enhanced midlevel westerly flow, associated with a
shortwave trough approaching from the west, is overspreading the
area and aiding in thunderstorm initiation over southeastern
Wyoming. This enhanced midlevel westerly flow, when coupled with
weak easterly upslope low-level flow over the central High Plains,
is resulting in effective bulk shear values around 50 knots across
much of the area. As the storms move eastward off the higher terrain
and encounter a more favorable thermodynamic environment over the
plains (MLCAPE over 2000 J/kg in the Nebraska Panhandle per SPC
mesoanalysis), they are expected to intensify posing a threat for
large hail initially (with mid-level lapse rates over 8 C/km).
Eventually, the storms are expected to grow upscale this evening
transitioning to a damaging-wind threat, especially as the
south-southwesterly low-level jet increases after dark.
..Jirak/Bunting.. 07/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LBF...GLD...BOU...CYS...
LAT...LON 39930487 40730543 41290549 41950539 42340499 42670407
42680338 42650252 42590188 42530127 42360086 41410045
40180041 39280145 39390314 39930487SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 9, 2:16 PM MDT | Severe Thunderstorm Watch | SPC | Logan, Morgan, Phillips, Sedgwick, Washington, Weld and 1 more | 9 hr |
| Jul 9, 5:16 PM MDT | Mesoscale Discussion | SPC | Logan, Phillips, Sedgwick, Yuma | 119 min |
| Jul 8, 8:33 PM MDT | Severe Thunderstorm Watch | SPC | Dakota, Dixon | 5 hr |
| Jul 9, 1:41 AM MDT | Mesoscale Discussion | SPC | Cedar, Dakota, Dixon | 34 min |
| Jul 9, 2:20 PM MDT | Mesoscale Discussion | SPC | Campbell, Crook, Johnson, Sheridan, Weston | 85 min |
| Jul 9, 5:33 PM MDT | Severe Thunderstorm Watch | SPC | Campbell, Crook, Weston | 4 hr |
Nearby
Mesoscale Discussions in Nebraska, 2021Mesoscale Discussions in Colorado, 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.