Alert archive / Kansas / Mesoscale Discussions in 2021
Mesoscale Discussion 1573
The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2021, 11:39 PM CDT for 13 counties in Kansas; 6 counties in Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2021, 11:39 PM CDT (04:39 UTC)
- Expired
- Aug 21, 2021, 1:45 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 454
Counties Allen County, KS, Anderson County, KS, Bourbon County, KS, Butler County, KS, Chautauqua County, KS, Cowley County, KS, Elk County, KS, Greenwood County, KS, Linn County, KS, Miami County, KS, Neosho County, KS, Wilson County, KS, Woodson County, KS, Bates County, MO, Cass County, MO, Henry County, MO, Johnson County, MO, Pettis County, MO, Vernon County, MO
The radar
The Topeka radar (KTWX), 135 km from the middle of the area, began a volume at 04:40 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, 4.7 hours before the alert went out and 117 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
- 3676 J/kg
- Mixed-layer CIN
- -53 J/kg
- Mixed-layer LCL
- 1017 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 145 m²/s²
- 0-3 km storm-relative helicity
- 242 m²/s²
- Significant tornado parameter
- 3.1
- Supercell composite
- 18.5
The text
As transmitted.
950 ACUS11 KWNS 210440 SWOMCD SPC MCD 210439 MOZ000-KSZ000-210645- Mesoscale Discussion 1573 NWS Storm Prediction Center Norman OK 1139 PM CDT Fri Aug 20 2021 Areas affected...Southeast KS...Western MO Concerning...Severe Thunderstorm Watch 454... Valid 210439Z - 210645Z The severe weather threat for Severe Thunderstorm Watch 454 continues. SUMMARY...Strong, to isolated severe, thunderstorms will propagate southeast across southeastern KS and western MO. Locally damaging winds appear to be the primary risk. DISCUSSION...Veered LLJ across northern OK into southwestern MO will gradually weaken and become more westerly during the early morning hours. As deep-layer flow becomes more westerly, ongoing corridor of thunderstorms will continue to propagate southeast across southeastern KS/western MO. Gusty winds have been common with this activity but most wind reports are not measured severe, though 40+kt winds are common in the Kansas City metro region. Given the lack of large-scale upper support, convective outflow will be modulated by an expansive precip shield that has evolved across northwestern MO into east-central KS. It appears a new watch is not warranted for this marginally severe activity. ..Darrow.. 08/21/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SGF...EAX...TOP...ICT... LAT...LON 37509755 38829425 38789312 38109362 37039655 37509755
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 7:06 PM CDT | Mesoscale Discussion | SPC | Allen, Anderson, Atchison, Brown, Butler, Chase and 29 more | 84 min |
| Aug 20, 7:40 PM CDT | Severe Thunderstorm Watch | SPC | Atchison, Doniphan, Douglas, Franklin, Jefferson, Johnson and 5 more | 5 hr |
| Aug 20, 9:37 PM CDT | Mesoscale Discussion | SPC | Allen, Anderson, Atchison, Brown, Butler, Chase and 23 more | 83 min |
Nearby
Mesoscale Discussions in Kansas, 2021Mesoscale Discussions in Missouri, 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.