Alert archive / Kansas / Mesoscale Discussions in 2021
Mesoscale Discussion 1687
The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2021, 7:15 PM CDT for 18 counties in Kansas. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Sep 2, 2021, 7:15 PM CDT (00:15 UTC)
- Expired
- Sep 2, 2021, 8:45 PM CDT
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 487
Counties Chase County, KS, Clay County, KS, Dickinson County, KS, Geary County, KS, Jackson County, KS, Lyon County, KS, Marion County, KS, Marshall County, KS, McPherson County, KS, Morris County, KS, Nemaha County, KS, Osage County, KS, Pottawatomie County, KS, Rice County, KS, Riley County, KS, Saline County, KS, Shawnee County, KS, Wabaunsee County, KS
The radar
The Topeka radar (KTWX), 45 km from the middle of the area, began a volume at 00:16 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
Topeka, KS (KTOP), launched 00:00Z, 0.3 hours before the alert went out and 96 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
- 155 J/kg
- Mixed-layer CIN
- -177 J/kg
- Mixed-layer LCL
- 1035 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 212 m²/s²
- 0-3 km storm-relative helicity
- 268 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.8
The text
As transmitted.
025
ACUS11 KWNS 030016
SWOMCD
SPC MCD 030015
KSZ000-030145-
Mesoscale Discussion 1687
NWS Storm Prediction Center Norman OK
0715 PM CDT Thu Sep 02 2021
Areas affected...portions of northeast Kansas
Concerning...Tornado Watch 487...
Valid 030015Z - 030145Z
The severe weather threat for Tornado Watch 487 continues.
SUMMARY...Damaging gusts and perhaps a brief tornado or two remain
possible over the next few hours.
DISCUSSION...Semi-discrete storms have developed over the past few
hours, with a couple of damaging gusts noted with cellular mergers.
These storms are progressing in a relatively pristine environment
characterized by up to 2000 J/kg MLCAPE. However, storms have
struggled to sustain steady state behavior in structure or
intensity, with recent severe potential mainly being confined to
storms progressing from Dickinson into Morris County, KS. Current
thinking is that storms will continue to fluctuate in intensity,
supporting occasional damaging gusts and perhaps a brief tornado,
especially farther north, where greater deep-layer ascent and
low-level/deep-layer shear are present. The severe threat may
persist for at least a couple hours after dark given a modest
expected increase in the nocturnal low-level jet.
..Squitieri/Guyer.. 09/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EAX...TOP...ICT...
LAT...LON 38299855 39259752 39839687 39889614 39629557 39129538
38649569 38359610 38129712 38299855SPC 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 | Ellis, Gove, Graham, Jewell, Lincoln, Mitchell and 8 more | 90 min |
| Sep 2, 9:24 PM CDT | Mesoscale Discussion | SPC | Chase, Dickinson, Geary, Lyon, Marion, Morris and 3 more | 96 min |
| Sep 3, 3:18 PM CDT | Mesoscale Discussion | SPC | Barber, Clark, Comanche, Ford, Harper, Kingman and 6 more | 2 hr |
Nearby
Mesoscale 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.