Alert archive / Iowa / Mesoscale Discussions in 2024
Mesoscale Discussion 855
The Storm Prediction Center issued this mesoscale discussion at May 20, 2024, 5:54 PM CDT for 27 counties in Iowa; 16 counties in Minnesota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 20, 2024, 5:54 PM CDT (22:54 UTC)
- Expired
- May 20, 2024, 8:00 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 43 counties
Buena Vista County, IA, Calhoun County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Emmet County, IA, Hancock County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Lyon County, IA, Mitchell County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Blue Earth County, MN, Dodge County, MN, Faribault County, MN, Freeborn County, MN, Goodhue County, MN, Jackson County, MN, Le Sueur County, MN, Martin County, MN, Mower County, MN, Nobles County, MN, Olmsted County, MN, Rice County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Watonwan County, MN
The radar
The Des Moines radar (KDMX), 177 km from the middle of the area, began a volume at 22:56 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
Minneapolis, MN (KMPX), launched 12:00Z, 10.9 hours before the alert went out and 187 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
- 685 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 52 m²/s²
- 0-3 km storm-relative helicity
- 101 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 20, 6:31 PM CDT | Severe Thunderstorm Watch | SPC | Harrison, Monona, Pottawattamie, Shelby | 5 hr |
| May 20, 6:45 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cerro Gordo, Cherokee, Clay, Crawford, Dickinson and 19 more | 5 hr |
Nearby
Mesoscale Discussions in Iowa, 2024Mesoscale Discussions in Minnesota, 2024Every mesoscale discussion in 2024
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.