Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 1688
The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2021, 8:50 PM CDT for 18 counties in Nebraska. It was in force for 85 min.
The area
The outline as issued.
The facts
- Issued
- Sep 2, 2021, 8:50 PM CDT (01:50 UTC)
- Expired
- Sep 2, 2021, 10:15 PM CDT
- In force
- 85 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 487
Counties Adams County, NE, Clay County, NE, Fillmore County, NE, Franklin County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Jefferson County, NE, Kearney County, NE, Merrick County, NE, Nuckolls County, NE, Phelps County, NE, Polk County, NE, Saline County, NE, Seward County, NE, Thayer County, NE, Webster County, NE, York County, NE
The radar
The Grand Island radar (KUEX), 31 km from the middle of the area, began a volume at 01:54 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 00:00Z, 1.8 hours before the alert went out and 176 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
- -244 J/kg
- Mixed-layer LCL
- 750 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 169 m²/s²
- 0-3 km storm-relative helicity
- 546 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
591
ACUS11 KWNS 030151
SWOMCD
SPC MCD 030150
NEZ000-KSZ000-030315-
Mesoscale Discussion 1688
NWS Storm Prediction Center Norman OK
0850 PM CDT Thu Sep 02 2021
Areas affected...portions of southern Nebraska into northern Kansas
Concerning...Tornado Watch 487...
Valid 030150Z - 030315Z
The severe weather threat for Tornado Watch 487 continues.
SUMMARY...A damaging gust or two remains possible with one of the
stronger storms, though the overall severe threat is expected to
diminish.
DISCUSSION...MRMS mosaic radar imagery depicts decreasing storm
coverage and an overall decrease in 30 dBZ echo top heights across
northwestern portions of Tornado Watch 487. As deep-layer ascent
continues to drift away from portions of south-central Nebraska in
tandem with nocturnal cooling, low-level lift will further weaken
with time, as will storm intensity. Nonetheless, given ample
vertical shear across the region and some residual buoyancy (1000+
J/kg MLCAPE), storms may remain organized enough to support a
damaging gust or two over the next couple of hours.
..Squitieri/Guyer.. 09/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OAX...TOP...GID...
LAT...LON 40349966 40849909 41329824 41369758 41109700 40629681
40199691 39999724 39969793 39949859 40079934 40349966SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 2, 7:00 PM CDT | Mesoscale Discussion | SPC | Adams, Buffalo, Clay, Fillmore, Franklin, Hall and 9 more | 90 min |
| Sep 3, 2:20 PM CDT | Mesoscale Discussion | SPC | Banner, Kimball, Scotts Bluff, Sioux | 55 min |
Nearby
Mesoscale Discussions in Nebraska, 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.