Alert archive / Iowa / Mesoscale Discussions in 2018
Mesoscale Discussion 310
The Storm Prediction Center issued this mesoscale discussion at May 1, 2018, 7:55 PM CDT for 54 counties in Iowa; 7 counties in Minnesota; Crawford County, La Crosse County, Vernon County, Wisconsin. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- May 1, 2018, 7:55 PM CDT (00:55 UTC)
- Expired
- May 1, 2018, 9:30 PM CDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
All 64 counties
Adair County, IA, Allamakee County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Crawford County, IA, Dallas County, IA, Delaware County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Iowa County, IA, Jasper County, IA, Kossuth County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mitchell County, IA, Palo Alto County, IA, Pocahontas County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Warren County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Winona County, MN, Crawford County, WI, La Crosse County, WI, Vernon County, WI
The radar
The La Crosse radar (KARX), 148 km from the middle of the area, began a volume at 00:58 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 nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 0.9 hours before the alert went out and 198 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
- 1425 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 75 m²/s²
- 0-3 km storm-relative helicity
- 99 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
731
ACUS11 KWNS 020056
SWOMCD
SPC MCD 020055
WIZ000-IAZ000-MNZ000-020230-
Mesoscale Discussion 0310
NWS Storm Prediction Center Norman OK
0755 PM CDT Tue May 01 2018
Areas affected...central IA into southeast MN and far southwest WI
Concerning...Severe Thunderstorm Watch 60...
Valid 020055Z - 020230Z
The severe weather threat for Severe Thunderstorm Watch 60
continues.
SUMMARY...Strong to severe storms will continue to pose mainly a
marginal hail threat the next few hours, with a gradual weakening
trend expected through the evening.
DISCUSSION...Several clusters of strong to severe thunderstorms are
ongoing this evening across IA. Some of these storms are ongoing in
isentropic ascent over the cold front, mainly from northwest into
north-central IA. Steep midlevel lapse rates and strong deep shear
is sufficient such that this elevated convection may produce some
marginally severe hail. South of the front across the warm sector,
weakening of convection is expected over the next few hours as the
boundary layer continues to stabilize with loss of daytime heating.
This gradual weakening trend has been noted in regional 7km and 9km
CAPPI, and is expected to continue. As a result, any damaging wind
threat should quickly diminish, but some marginal hail threat could
still persist for another few hours.
..Leitman.. 05/02/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DVN...ARX...MPX...DMX...FSD...OAX...
LAT...LON 43609038 41179246 41199570 42379548 43279506 43739392
43989295 44059256 43979118 43929068 43609038SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 7:24 PM CDT | Mesoscale Discussion | SPC | Adams, Cass, Fremont, Harrison, Mills, Montgomery and 4 more | 2 hr |
| May 1, 9:38 PM CDT | Mesoscale Discussion | SPC | Adair, Audubon, Benton, Black Hawk, Boone, Bremer and 29 more | 67 min |
| May 2, 1:33 PM CDT | Mesoscale Discussion | SPC | Cedar, Clinton, Des Moines, Henry, Jackson, Jefferson and 9 more | 117 min |
| May 2, 3:56 PM CDT | Severe Thunderstorm Watch | SPC | Cedar, Clinton, Des Moines, Henry, Iowa, Jackson and 10 more | 9 hr |
| May 2, 5:08 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Clarke, Davis, Decatur and 15 more | 97 min |
| May 2, 5:27 PM CDT | Tornado Watch | SPC | Adams, Appanoose, Clarke, Davis, Decatur, Lucas and 9 more | 8 hr |
Nearby
Mesoscale Discussions in Iowa, 2018Mesoscale Discussions in Minnesota, 2018Mesoscale Discussions in Wisconsin, 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.