Alert archive / Kansas / Mesoscale Discussions in 2021
Mesoscale Discussion 1568
The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2021, 3:57 PM CDT for 42 counties in Kansas; 6 counties in Nebraska. It was in force for 63 min.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2021, 3:57 PM CDT (20:57 UTC)
- Expired
- Aug 20, 2021, 5:00 PM CDT
- In force
- 63 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 48 counties
Atchison County, KS, Barber County, KS, Barton County, KS, Brown County, KS, Butler County, KS, Chase County, KS, Clark County, KS, Clay County, KS, Cloud County, KS, Comanche County, KS, Dickinson County, KS, Doniphan County, KS, Douglas County, KS, Edwards County, KS, Ellsworth County, KS, Geary County, KS, Harvey County, KS, Jackson County, KS, Jefferson County, KS, Kingman County, KS, Kiowa County, KS, Lincoln County, KS, Lyon County, KS, Marion County, KS, Marshall County, KS, McPherson County, KS, Morris County, KS, Nemaha County, KS, Osage County, KS, Ottawa County, KS, Pottawatomie County, KS, Pratt County, KS, Reno County, KS, Republic County, KS, Rice County, KS, Riley County, KS, Saline County, KS, Sedgwick County, KS, Shawnee County, KS, Stafford County, KS, Wabaunsee County, KS, Washington County, KS, Gage County, NE, Jefferson County, NE, Johnson County, NE, Nemaha County, NE, Pawnee County, NE, Richardson County, NE
The radar
The Topeka radar (KTWX), 100 km from the middle of the area, began a volume at 20:59 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, 9.0 hours before the alert went out and 148 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
- 1273 J/kg
- Mixed-layer CIN
- -61 J/kg
- Mixed-layer LCL
- 702 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 148 m²/s²
- 0-3 km storm-relative helicity
- 138 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.7
The text
As transmitted.
448
ACUS11 KWNS 202057
SWOMCD
SPC MCD 202057
MOZ000-KSZ000-NEZ000-OKZ000-202200-
Mesoscale Discussion 1568
NWS Storm Prediction Center Norman OK
0357 PM CDT Fri Aug 20 2021
Areas affected...central kansas
Concerning...Severe potential...Watch possible
Valid 202057Z - 202200Z
Probability of Watch Issuance...40 percent
SUMMARY...A few severe storms with a threat for damaging winds and
hail are expected to form along a cold front this afternoon/evening.
A weather watch is possible.
DISCUSSION...On the southern fringes of a northern Plains trough,
afternoon visible imagery showed towering cumulus developing along a
southwest to northeast oriented cold front across Kansas. Severe
thunderstorm development is possible this afternoon/evening as the
environment continues to destabilize to the east of the front. SPC
MESOANALYSIS shows a corridor of 1500-3000 J/kg of MLCAPE across
much of Kansas with the greatest instability located across the
northeastern portions of the State. Within this area, steadily
increasing mid-level flow will support 25-40 kts of effective shear
this afternoon/evening. Strong forcing along the front and DCAPE
greater than 1300 J/kg will support strong downdrafts and surface
cold pools. As such, a few organized clusters or line segments
capable of damaging winds may evolve. The degree of buoyancy may
also support a severe hail risk despite modest mid-level lapse
rates.
Farther southwest along the front, effective shear and instability
are more limited. While isolated severe storm development across
southwestern and central Kansas is possible, uncertainty on storm
coverage remains much higher. Convective trends will be monitored
for a possible weather watch.
..Lyons/Guyer.. 08/20/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EAX...OAX...TOP...ICT...OUN...GID...DDC...
LAT...LON 37219814 36959963 37230005 38069926 39039836 40049761
40399741 40519707 40549620 40439547 39909511 39159509
38469551 38059620 37609709 37519725 37359766 37219814SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 9:27 PM CDT | Mesoscale Discussion | SPC | Cheyenne, Decatur, Norton, Rawlins, Sheridan, Sherman and 1 more | 93 min |
| Aug 19, 10:55 PM CDT | Mesoscale Discussion | SPC | Graham, Jewell, Norton, Osborne, Phillips, Rooks and 1 more | 95 min |
| Aug 20, 4:39 PM CDT | Severe Thunderstorm Watch | SPC | Brown, Clay, Cloud, Dickinson, Geary, Jackson and 12 more | 6 hr |
| Aug 20, 1:51 PM CDT | Mesoscale Discussion | SPC | Burt, Butler, Cass, Cedar, Colfax, Cuming and 22 more | 84 min |
| Aug 20, 3:58 PM CDT | Severe Thunderstorm Watch | SPC | Dakota, Dixon | 6 hr |
Nearby
Mesoscale Discussions in Kansas, 2021Mesoscale 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.