Alert archive / Iowa / Mesoscale Discussions in 2020
Mesoscale Discussion 813
The Storm Prediction Center issued this mesoscale discussion at Jun 4, 2020, 12:59 PM CDT for 35 counties in Iowa. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- Jun 4, 2020, 12:59 PM CDT (17:59 UTC)
- Expired
- Jun 4, 2020, 2:00 PM CDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 35 counties
Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Buchanan County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cedar County, IA, Crawford County, IA, Dallas County, IA, Delaware County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Humboldt County, IA, Iowa County, IA, Jasper County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Marshall County, IA, Muscatine County, IA, Pocahontas County, IA, Polk County, IA, Poweshiek County, IA, Sac County, IA, Scott County, IA, Story County, IA, Tama County, IA, Webster County, IA, Wright County, IA
The radar
The Des Moines radar (KDMX), 59 km from the middle of the area, began a volume at 18:02 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
Davenport, (KDVN), launched 12:00Z, 6.0 hours before the alert went out and 228 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
- 451 J/kg
- Mixed-layer CIN
- -72 J/kg
- Mixed-layer LCL
- 1180 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- -41 m²/s²
- 0-3 km storm-relative helicity
- 30 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
827
ACUS11 KWNS 041800
SWOMCD
SPC MCD 041759
IAZ000-041900-
Mesoscale Discussion 0813
NWS Storm Prediction Center Norman OK
1259 PM CDT Thu Jun 04 2020
Areas affected...Central Iowa
Concerning...Severe potential...Watch unlikely
Valid 041759Z - 041900Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated to scattered thunderstorm development is probable
through the mid afternoon, but most storms should remain below
severe limits. A watch is not likely.
DISCUSSION...Agitated cumulus and a few weak thunderstorms have
developed along and north of a stationary boundary draped east-west
across Iowa. As daytime heating and decreasing inhibition continue,
additional thunderstorms are probable. Given 500-1000 J/kg, with
pockets up to 1500 J/kg, of MLCAPE, a strong storm or two is
possible and may occasionally be capable of marginally severe hail.
However, deep layer shear is currently weak and is not expected to
increase above 25 knots until the late afternoon/evening hours.
Given the low probability for severe hail and wind in this area, a
watch is not likely for this round of developing convection.
..Moore/Grams.. 06/04/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DVN...ARX...DMX...FSD...OAX...
LAT...LON 42199548 42779522 42809434 42689227 42499090 42119060
41699050 41369118 41349258 41499428 41789538 42199548SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 3, 8:54 PM CDT | Mesoscale Discussion | SPC | Fremont | 2 hr |
| Jun 3, 10:44 PM CDT | Mesoscale Discussion | SPC | Fremont | 2 hr |
| Jun 4, 5:14 PM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 61 more | 91 min |
Nearby
Mesoscale Discussions in Iowa, 2020Every mesoscale discussion in 2020
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.