Alert archive / Kansas / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 73

April 6, 202128 counties in Kansas

The Storm Prediction Center issued this severe thunderstorm watch at Apr 6, 2021, 9:06 PM CDT for 28 counties in Kansas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Apr 6, 2021, 9:06 PM CDT (02:06 UTC)
Expired
Apr 7, 2021, 2:00 AM CDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 28 counties

Anderson County, KS, Chase County, KS, Clay County, KS, Cloud County, KS, Coffey County, KS, Dickinson County, KS, Douglas County, KS, Ellsworth County, KS, Franklin County, KS, Geary County, KS, Harvey County, KS, Kingman County, KS, Lyon County, KS, Marion County, KS, Marshall County, KS, McPherson County, KS, Morris County, KS, Osage County, KS, Ottawa County, KS, Pottawatomie County, KS, Reno County, KS, Republic County, KS, Rice County, KS, Riley County, KS, Saline County, KS, Shawnee County, KS, Wabaunsee County, KS, Washington County, KS

The radar

The Topeka radar (KTWX), 24 km from the middle of the area, began a volume at 02:06 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
10%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
40%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Apr 6, 10:31 PM CDTSevere Thunderstorm WarningICTBarton, Rice59 min
Apr 6, 10:54 PM CDTSevere Thunderstorm WarningICTEllsworth, Rice66 min
Apr 6, 11:41 PM CDTSevere Thunderstorm WarningICTRice40 min
Apr 6, 11:56 PM CDTSevere Thunderstorm WarningICTEllsworth, McPherson, Rice, Saline25 min
Apr 7, 1:35 AM CDTSevere Thunderstorm WarningICTChase, Marion23 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Topeka, KS (KTOP), launched 00:00Z, 2.1 hours before the alert went out and 73 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.

Skew-T log-pSkew-T log-p diagram, Topeka, KS at 00:00Z on 2021-04-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 342 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Topeka, KS at 00:00Z on 2021-04-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 67 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
342 J/kg
Mixed-layer CIN
-206 J/kg
Mixed-layer LCL
1225 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
67 m²/s²
0-3 km storm-relative helicity
186 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0

Open this sounding in Storm Lab

The text

As transmitted.

167 
WWUS20 KWNS 070203
SEL3  
SPC WW 070203
KSZ000-070700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 73
NWS Storm Prediction Center Norman OK
905 PM CDT Tue Apr 6 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Northeast Kansas

* Effective this Tuesday night and Wednesday morning from 905 PM
  until 200 AM CDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph possible
  Scattered large hail events to 1.5 inches in diameter possible

SUMMARY...Earlier supercells in central Kansas have evolved into
more of a linear configuration, which suggests more of a damaging
wind threat into the overnight hours as the storms spread eastward. 
The stronger storms will also continue to pose a threat for
occasional large hail.

The severe thunderstorm watch area is approximately along and 65
statute miles east and west of a line from 45 miles north of
Manhattan KS to 35 miles west southwest of Emporia KS. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 72...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
26025.

...Thompson

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 6, 7:10 PM CDTMesoscale DiscussionSPCBarton, Edwards, Ellis, Ellsworth, Jewell, Kingman and 14 more2 hr
Apr 6, 9:11 PM CDTMesoscale DiscussionSPCBarton, Clay, Cloud, Dickinson, Ellsworth, Geary and 8 more2 hr
Apr 6, 11:22 PM CDTMesoscale DiscussionSPCChase, Harvey, Kingman, Lyon, McPherson, Marion and 3 more113 min
Apr 7, 10:18 AM CDTMesoscale DiscussionSPCJohnson, Miami, Wyandotte117 min

Nearby

Severe Thunderstorm Watches in Kansas, 2021Every severe thunderstorm watch 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.