Alert archive / Iowa / Mesoscale Discussions in 2021
Mesoscale Discussion 1212
The Storm Prediction Center issued this mesoscale discussion at Jul 9, 2021, 1:28 PM CDT for 5 counties in Iowa. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 9, 2021, 1:28 PM CDT (18:28 UTC)
- Expired
- Jul 9, 2021, 3:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Boone County, IA, Dallas County, IA, Lucas County, IA, Polk County, IA, Warren County, IA
The radar
The Des Moines radar (KDMX), 13 km from the middle of the area, began a volume at 18:29 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, 6.5 hours before the alert went out and 229 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
- 428 J/kg
- Mixed-layer CIN
- -350 J/kg
- Mixed-layer LCL
- 881 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- 404 m²/s²
- 0-3 km storm-relative helicity
- 551 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.9
The text
As transmitted.
348
ACUS11 KWNS 091829
SWOMCD
SPC MCD 091828
IAZ000-092030-
Mesoscale Discussion 1212
NWS Storm Prediction Center Norman OK
0128 PM CDT Fri Jul 09 2021
Areas affected...Central Iowa
Concerning...Severe potential...Watch unlikely
Valid 091828Z - 092030Z
Probability of Watch Issuance...20 percent
SUMMARY...An elevated severe-hail-producing storm in Boone County
Iowa may persist for the next couple of hours. Given the expected
limited spatiotemporal nature of the hail threat, a severe
thunderstorm watch is currently not anticipated.
DISCUSSION...An isolated thunderstorm has developed in a
warm-advection regime across central Iowa with a history of
producing severe hail. Given the favorable MUCAPE and effective
deep-layer shear, severe hail will continue to be a threat from this
storm as it moves south-southeastward along the instability
gradient. Additional severe storms are not anticipated until later
this afternoon/evening when better large-scale forcing for ascent
moves in from the west. Thus, a watch is currently not anticipated
over the next couple hours, but convective trends will continue to
be monitored.
..Jirak/Bunting.. 07/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DMX...
LAT...LON 42049415 42219394 42079356 41659328 41329316 41089321
40929348 41289397 42049415SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 8, 9:33 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Ida, Lyon, O'Brien and 3 more | 5 hr |
| Jul 9, 2:41 AM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Clay, Crawford, Ida, Lyon and 6 more | 34 min |
| Jul 9, 5:40 PM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Bremer, Buchanan, Butler, Cedar and 15 more | 95 min |
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.