Alert archive / Iowa / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 308
The Storm Prediction Center issued this severe thunderstorm watch at Jun 24, 2021, 2:20 AM CDT for 4 states. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 24, 2021, 2:20 AM CDT (07:20 UTC)
- Expired
- Jun 24, 2021, 8:30 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 65 kt
All 46 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Boone County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Crawford County, IA, Dallas County, IA, Decatur County, IA, Greene County, IA, Guthrie County, IA, Madison County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Ringgold County, IA, Story County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Atchison County, KS, Brown County, KS, Doniphan County, KS, Nemaha County, KS, Andrew County, MO, Atchison County, MO, Buchanan County, MO, Caldwell County, MO, Clinton County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Livingston County, MO, Mercer County, MO, Nodaway County, MO, Worth County, MO, Gage County, NE, Johnson County, NE, Nemaha County, NE, Pawnee County, NE, Richardson County, NE, Saline County, NE
The radar
The Omaha radar (KOAX), 127 km from the middle of the area, began a volume at 07:18 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.
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
- 5%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 50%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 24, 2:24 AM CDT | Severe Thunderstorm Warning | OAX | Cass, Gage, Jefferson, Lancaster, Otoe, Saline and 1 more | 51 min |
| Jun 24, 2:51 AM CDT | Severe Thunderstorm Warning | OAX | Fremont, Mills, Montgomery | 39 min |
| Jun 24, 2:54 AM CDT | Severe Thunderstorm Warning | OAX | Cass, Gage, Johnson, Lancaster, Otoe, Sarpy | 36 min |
| Jun 24, 3:17 AM CDT | Severe Thunderstorm Warning | OAX | Fremont, Mills, Montgomery, Page | 58 min |
| Jun 24, 3:28 AM CDT | Severe Thunderstorm Warning | EAX | Atchison | 47 min |
| Jun 24, 4:14 AM CDT | Severe Thunderstorm Warning | EAX | Atchison, Holt, Nodaway | 28 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
Omaha, NE (KOAX), launched 00:00Z, 7.3 hours before the alert went out and 127 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
- 2039 J/kg
- Mixed-layer CIN
- -306 J/kg
- Mixed-layer LCL
- 1664 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 60 m²/s²
- 0-3 km storm-relative helicity
- 168 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted.
392
WWUS20 KWNS 240718
SEL8
SPC WW 240718
IAZ000-KSZ000-MOZ000-NEZ000-241500-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 308
NWS Storm Prediction Center Norman OK
215 AM CDT Thu Jun 24 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western and central Iowa
Extreme northeastern Kansas
Northwestern Missouri
Southeastern Nebraska
* Effective this Thursday morning from 215 AM until 1000 AM CDT.
* Primary threats include...
Scattered damaging winds and isolated significant gusts to 75
mph possible
Isolated large hail events to 1.5 inches in diameter possible
SUMMARY...A severe thunderstorm complex initially over eastern
Nebraska has a strong pressure/thermal perturbation and intense
rear-inflow jet, along with history of measured gusts up to 73 kt.
This activity is expected to maintain severe-wind potential east of
watch 307 into parts of adjoining Iowa, northwestern Missouri and
perhaps northeastern Kansas, before it encounters more-stable air
near I-35 and weakens later this morning.
The severe thunderstorm watch area is approximately along and 70
statute miles either side of a line from 35 miles south of Falls
City NE to 30 miles northwest of Des Moines IA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).
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 307...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
24035.
...EdwardsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 23, 8:10 PM CDT | Mesoscale Discussion | SPC | Monona, Plymouth, Woodbury | 95 min |
| Jun 23, 10:12 PM CDT | Mesoscale Discussion | SPC | Harrison, Mills, Monona, Pottawattamie | 93 min |
| Jun 23, 10:37 PM CDT | Severe Thunderstorm Watch | SPC | Fremont, Harrison, Mills, Monona, Pottawattamie, Shelby and 1 more | 6 hr |
| Jun 24, 1:36 AM CDT | Mesoscale Discussion | SPC | Adams, Cass, Fremont, Harrison, Mills, Montgomery and 4 more | 114 min |
| Jun 24, 5:02 AM CDT | Mesoscale Discussion | SPC | Appanoose, Clarke, Davis, Decatur, Lucas, Madison and 8 more | 118 min |
| Jun 24, 3:44 PM CDT | Tornado Watch | SPC | Fremont, Page | 5 hr |
| Jun 24, 5:30 PM CDT | Mesoscale Discussion | SPC | Fremont, Page | 60 min |
| Jun 24, 6:19 PM CDT | Mesoscale Discussion | SPC | Appanoose, Clarke, Davis, Decatur, Lucas, Monroe and 3 more | 56 min |
| Jun 24, 6:33 PM CDT | Tornado Watch | SPC | Adams, Appanoose, Clarke, Davis, Decatur, Lucas and 6 more | 3 hr |
| Jun 24, 2:45 PM CDT | Mesoscale Discussion | SPC | Atchison, Brown, Douglas, Jackson, Jefferson, Leavenworth and 7 more | 3 hr |
| Jun 24, 2:49 PM CDT | Mesoscale Discussion | SPC | Cheyenne, Logan, Rawlins, Sherman, Thomas, Wallace | 116 min |
| Jun 24, 3:14 PM CDT | Mesoscale Discussion | SPC | Gray, Haskell, Meade, Seward | 91 min |
| Jun 24, 4:56 PM CDT | Severe Thunderstorm Watch | SPC | Cheyenne, Decatur, Finney, Gove, Grant, Gray and 13 more | 6 hr |
| Jun 24, 6:31 PM CDT | Mesoscale Discussion | SPC | Cheyenne, Greeley, Hamilton, Kearny, Lane, Logan and 6 more | 119 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2021Severe Thunderstorm Watches in Missouri, 2021Severe Thunderstorm Watches in Nebraska, 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.