Alert archive / Iowa / Mesoscale Discussions in 2021
Mesoscale Discussion 1286
The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2021, 4:17 PM CDT for 11 counties in Iowa. It was in force for 58 min.
The area
The outline as issued.
The facts
- Issued
- Jul 14, 2021, 4:17 PM CDT (21:17 UTC)
- Expired
- Jul 14, 2021, 5:15 PM CDT
- In force
- 58 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 378
Counties Boone County, IA, Butler County, IA, Calhoun County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Hamilton County, IA, Hardin County, IA, Humboldt County, IA, Webster County, IA, Wright County, IA
The radar
The Des Moines radar (KDMX), 80 km from the middle of the area, began a volume at 21:18 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.
The nearest sounding before it
Omaha, NE (KOAX), launched 12:00Z, 9.3 hours before the alert went out and 243 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
- 967 J/kg
- Mixed-layer CIN
- -125 J/kg
- Mixed-layer LCL
- 1201 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 35 m²/s²
- 0-3 km storm-relative helicity
- -7 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.1
The text
As transmitted.
985
ACUS11 KWNS 142118
SWOMCD
SPC MCD 142117
IAZ000-142215-
Mesoscale Discussion 1286
NWS Storm Prediction Center Norman OK
0417 PM CDT Wed Jul 14 2021
Areas affected...Central/northern Iowa
Concerning...Tornado Watch 378...
Valid 142117Z - 142215Z
The severe weather threat for Tornado Watch 378 continues.
SUMMARY...Two supercell thunderstorms in central Iowa have recently
had observed tornadoes reported. The mesoscale environment will
continue to favor supercells with an attendant tornado threat.
DISCUSSION...A supercell thunderstorm in Calhoun County has recently
had a tornado reported with it. A newer storm to the east in
Hamilton County has also shown supercell structure with a weak TDS
signature on the 0.5 degree KDMX 2109Z scan. These storms are
interacting favorably with outflow from a convective complex that
moved through the region earlier today. This favorable mesoscale
environment will continue to support supercell storms with tornadic
potential this afternoon.
..Wendt.. 07/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ARX...DMX...
LAT...LON 42519487 42859419 42979282 42739241 42269248 42049373
41999444 42119485 42519487SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 7:02 AM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 43 more | 2 hr |
| Jul 14, 8:54 AM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 13 more | 5 hr |
| Jul 14, 11:45 AM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton, Dubuque, Jackson, Jones | 2 hr |
| Jul 14, 1:40 PM CDT | Mesoscale Discussion | SPC | Audubon, Black Hawk, Boone, Bremer, Buena Vista, Butler and 38 more | 2 hr |
| Jul 14, 2:35 PM CDT | Tornado Watch | SPC | Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 41 more | 8 hr |
| Jul 14, 5:42 PM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton, Delaware, Dubuque, Jackson, Jones | 63 min |
| Jul 14, 5:47 PM CDT | Mesoscale Discussion | SPC | Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 29 more | 118 min |
| Jul 14, 6:13 PM CDT | Tornado Watch | SPC | Allamakee, Cedar, Clayton, Clinton, Delaware, Dubuque and 7 more | 6 hr |
Nearby
Mesoscale Discussions in Iowa, 2021Every mesoscale discussion 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.