Alert archive / Iowa / Mesoscale Discussions in 2018
Mesoscale Discussion 802
The Storm Prediction Center issued this mesoscale discussion at Jun 20, 2018, 1:01 PM CDT for 22 counties in Iowa. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 20, 2018, 1:01 PM CDT (18:01 UTC)
- Expired
- Jun 20, 2018, 3:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 22 counties
Benton County, IA, Boone County, IA, Dallas County, IA, Grundy County, IA, Hardin County, IA, Iowa County, IA, Jasper County, IA, Johnson County, IA, Keokuk County, IA, Linn County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Wapello County, IA, Warren County, IA, Washington County, IA
The radar
The Des Moines radar (KDMX), 75 km from the middle of the area, began a volume at 18:00 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
Davenport, (KDVN), launched 12:00Z, 6.0 hours before the alert went out and 193 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
- 235 J/kg
- Mixed-layer CIN
- -52 J/kg
- Mixed-layer LCL
- 502 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 80 m²/s²
- 0-3 km storm-relative helicity
- 80 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
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 |
|---|---|---|---|---|
| Jun 20, 3:04 PM CDT | Tornado Watch | SPC | Benton, Black Hawk, Boone, Bremer, Buchanan, Butler and 30 more | 4 hr |
| Jun 20, 5:13 PM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Bremer, Buchanan, Butler, Cedar and 31 more | 2 hr |
Nearby
Mesoscale Discussions in Iowa, 2018Every mesoscale discussion in 2018
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.