Alert archive / Iowa / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 358
The Storm Prediction Center issued this severe thunderstorm watch at Jul 9, 2021, 7:08 PM CDT for 4 counties in Illinois; 10 counties in Iowa; Clark County, Scotland County, Missouri. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 9, 2021, 7:08 PM CDT (00:08 UTC)
- Expired
- Jul 9, 2021, 10:36 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
Counties Des Moines County, IA, Henry County, IA, Iowa County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Van Buren County, IA, Washington County, IA, Hancock County, IL, Henderson County, IL, McDonough County, IL, Warren County, IL, Clark County, MO, Scotland County, MO
The radar
The Quad Cities radar (KDVN), 87 km from the middle of the area, began a volume at 00:08 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
- 10%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 60%
- One or more hailstones of 2 inches or more
- 60%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 9, 7:08 PM CDT | Severe Thunderstorm Warning | DVN | Hancock, Henderson, McDonough, Warren | 37 min |
| Jul 9, 7:19 PM CDT | Severe Thunderstorm Warning | DVN | Hancock, Henderson, McDonough | 41 min |
| Jul 9, 7:29 PM CDT | Severe Thunderstorm Warning | DVN | Iowa, Johnson, Keokuk, Louisa, Washington | 31 min |
| Jul 9, 7:39 PM CDT | Severe Thunderstorm Warning | DVN | Hancock, Henderson, McDonough, Warren | 66 min |
| Jul 9, 7:51 PM CDT | Severe Thunderstorm Warning | DVN | Henry, Jefferson, Keokuk, Washington | 24 min |
| Jul 9, 8:25 PM CDT | Severe Thunderstorm Warning | DVN | Henry, Lee, Van Buren | 35 min |
| Jul 9, 8:57 PM CDT | Severe Thunderstorm Warning | DVN | Hancock | 33 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
Davenport, (KDVN), launched 00:00Z, 0.1 hours before the alert went out and 93 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1111 m above ground
- 0-6 km bulk shear
- 50 kt
- 0-1 km storm-relative helicity
- 19 m²/s²
- 0-3 km storm-relative helicity
- 114 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
The text
As transmitted.
078
WWUS20 KWNS 100005
SEL8
SPC WW 100005
IAZ000-ILZ000-MOZ000-100500-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 358
NWS Storm Prediction Center Norman OK
705 PM CDT Fri Jul 9 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southeast Iowa
Extreme northwest Illinois
Extreme northeast Missouri
* Effective this Friday night from 705 PM until Midnight CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2.5
inches in diameter likely
Scattered damaging wind gusts to 70 mph possible
SUMMARY...A small cluster of elevated storms, some with supercell
structures, may persist for the next few hours while moving
southeastward near the Illinois, Iowa, Missouri border region.
Isolated very large hail and severe wind gusts will be the main
threats.
The severe thunderstorm watch area is approximately along and 35
statute miles east and west of a line from 65 miles north northwest
of Burlington IA to 35 miles south southwest of Burlington 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 356...WW 357...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
31025.
...ThompsonSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 9, 7:54 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calhoun, Cass, Greene, Jersey and 9 more | 36 min |
| Jul 9, 8:18 PM CDT | Tornado Watch | SPC | Adams, Brown, Calhoun, Cass, Greene, Jersey and 9 more | 6 hr |
| Jul 9, 10:26 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calhoun, Cass, Greene, Jersey and 7 more | 64 min |
| Jul 10, 1:01 AM CDT | Mesoscale Discussion | SPC | Clinton, Jackson, Monroe, Perry, Randolph, Saint Clair and 3 more | 59 min |
| Jul 10, 1:36 AM CDT | Severe Thunderstorm Watch | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Jackson and 10 more | 4 hr |
| Jul 10, 3:09 AM CDT | Mesoscale Discussion | SPC | Alexander, Franklin, Jackson, Johnson, Pulaski, Saline and 2 more | 2 hr |
| Jul 10, 1:25 PM CDT | Mesoscale Discussion | SPC | Alexander, Clay, Clinton, Edwards, Franklin, Gallatin and 22 more | 2 hr |
| Jul 10, 2:01 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Bond, Clay, Clinton, Crawford, Edwards and 28 more | 8 hr |
| Jul 10, 3:09 PM CDT | Mesoscale Discussion | SPC | Cass, Champaign, DeWitt, Douglas, Ford, Logan and 8 more | 96 min |
| Jul 10, 5:33 PM CDT | Mesoscale Discussion | SPC | Clay, Edwards, Franklin, Gallatin, Hamilton, Hardin and 10 more | 87 min |
| Jul 9, 9:12 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Cass, Fremont, Harrison, Mills and 7 more | 2 hr |
| Jul 9, 9:58 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Audubon, Carroll, Cass, Clarke and 16 more | 7 hr |
| Jul 10, 1:20 PM CDT | Mesoscale Discussion | SPC | Fremont, Mills, Montgomery, Page | 115 min |
| Jul 10, 2:18 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Audubon, Cass, Fremont, Harrison, Mills and 5 more | 7 hr |
| Jul 10, 3:44 PM CDT | Mesoscale Discussion | SPC | Fremont, Page | 91 min |
| Jul 10, 1:21 AM CDT | Mesoscale Discussion | SPC | Andrew, Atchison, Buchanan, Caldwell, Clay, Clinton and 11 more | 84 min |
| Jul 10, 2:57 AM CDT | Mesoscale Discussion | SPC | Bates, Caldwell, Carroll, Cass, Chariton, Clay and 20 more | 93 min |
| Jul 10, 5:04 AM CDT | Mesoscale Discussion | SPC | Butler, Carter, Ripley, Stoddard | 56 min |
| Jul 10, 11:37 AM CDT | Mesoscale Discussion | SPC | Barry, Christian, Douglas, Howell, Laclede, McDonald and 9 more | 83 min |
| Jul 10, 2:17 PM CDT | Mesoscale Discussion | SPC | Barry, Barton, Jasper, McDonald, Newton, Vernon | 118 min |
| Jul 10, 3:02 PM CDT | Severe Thunderstorm Watch | SPC | Barry, Barton, Camden, Cedar, Christian, Dade and 26 more | 8 hr |
| Jul 10, 5:27 PM CDT | Mesoscale Discussion | SPC | Andrew, Buchanan, Caldwell, Carroll, Clay, Clinton and 13 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Iowa, 2021Severe Thunderstorm Watches in Illinois, 2021Severe Thunderstorm Watches in Missouri, 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.