Alert archive / Missouri / Mesoscale Discussions in 2021
Mesoscale Discussion 1769
The Storm Prediction Center issued this mesoscale discussion at Sep 20, 2021, 2:15 PM CDT for 4 counties in Kansas; 35 counties in Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 20, 2021, 2:15 PM CDT (19:15 UTC)
- Expired
- Sep 20, 2021, 4:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 39 counties
Johnson County, KS, Leavenworth County, KS, Miami County, KS, Wyandotte County, KS, Adair County, MO, Bates County, MO, Benton County, MO, Buchanan County, MO, Caldwell County, MO, Carroll County, MO, Cass County, MO, Chariton County, MO, Clay County, MO, Clinton County, MO, Cooper County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Henry County, MO, Howard County, MO, Jackson County, MO, Johnson County, MO, Lafayette County, MO, Linn County, MO, Livingston County, MO, Macon County, MO, Mercer County, MO, Moniteau County, MO, Morgan County, MO, Pettis County, MO, Platte County, MO, Putnam County, MO, Randolph County, MO, Ray County, MO, Saline County, MO, St. Clair County, MO, Sullivan County, MO
The radar
The Pleasant Hill radar (KEAX), 56 km from the middle of the area, began a volume at 19:18 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
Topeka, KS (KTOP), launched 12:00Z, 7.3 hours before the alert went out and 165 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
- 583 J/kg
- Mixed-layer CIN
- -288 J/kg
- Mixed-layer LCL
- 1142 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 59 m²/s²
- 0-3 km storm-relative helicity
- 185 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.5
The text
As transmitted.
641
ACUS11 KWNS 201915
SWOMCD
SPC MCD 201915
MOZ000-KSZ000-202115-
Mesoscale Discussion 1769
NWS Storm Prediction Center Norman OK
0215 PM CDT Mon Sep 20 2021
Areas affected...far northeast Kansas through northern and central
Missouri
Concerning...Severe potential...Watch possible
Valid 201915Z - 202115Z
Probability of Watch Issuance...60 percent
SUMMARY...Thunderstorms are expected to develop over far northeast
Kansas by 20Z, likely evolving into a line as they continue east
through northern Missouri into the evening. Locally strong to severe
wind gusts will be the primary threat, though a few instances of
hail may also occur in the stronger storms. A severe thunderstorm
watch might be needed for this region by 20-21Z.
DISCUSSION...Early this afternoon a cold front extends from western
IA through northeast KS near Topeka, then farther southwest near
Wichita. The downstream warm sector has become moderately unstable
with 1500-2000 J/kg MLCAPE as surface temperatures climb through the
80s along with upper 60s to near 70 F dewpoints. Deeper forcing and
stronger winds aloft attending a northern-stream shortwave trough
will remain north of this region. Nevertheless, forcing for ascent
within frontal zone should become sufficient to initiate storms over
northeast KS as the boundary layer continues to destabilize and any
remaining convective inhibition weakens. Vertical wind profiles with
30-35 kt effective bulk shear will support multicell storm modes,
with storms likely to eventually evolve into line segments along the
front. The stronger storms will become capable of producing strong
to damaging gusts, especially as they continue east through northern
MO later this afternoon into the evening.
..Dial/Hart.. 09/20/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LSX...SGF...EAX...
LAT...LON 37899444 38349489 39159508 39859494 40399440 40539320
40399249 39749209 38859236 38229286 37889363 37899444SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 20, 3:25 PM CDT | Severe Thunderstorm Watch | SPC | Bourbon, Johnson, Leavenworth, Linn, Miami, Wyandotte | 7 hr |
| Sep 20, 6:25 PM CDT | Mesoscale Discussion | SPC | Bourbon, Johnson, Linn, Miami, Wyandotte | 95 min |
| Sep 20, 12:38 PM CDT | Mesoscale Discussion | SPC | Mercer, Putnam, Worth | 2 hr |
Nearby
Mesoscale Discussions in Missouri, 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.