Alert archive / Iowa / Mesoscale Discussions in 2021
Mesoscale Discussion 984
The Storm Prediction Center issued this mesoscale discussion at Jun 16, 2021, 6:26 PM CDT for 22 counties in Iowa; 7 counties in Minnesota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 16, 2021, 6:26 PM CDT (23:26 UTC)
- Expired
- Jun 16, 2021, 8:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 29 counties
Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Emmet County, IA, Greene County, IA, Humboldt County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Webster County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN
The radar
The Sioux Falls radar (KFSD), 121 km from the middle of the area, began a volume at 23:30 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, 11.4 hours before the alert went out and 196 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
- 1960 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 169 m²/s²
- 0-3 km storm-relative helicity
- 352 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 9.1
The text
As transmitted.
895
ACUS11 KWNS 162326
SWOMCD
SPC MCD 162326
IAZ000-MNZ000-NEZ000-SDZ000-170130-
Mesoscale Discussion 0984
NWS Storm Prediction Center Norman OK
0626 PM CDT Wed Jun 16 2021
Areas affected...Southwest Minnesota into western Iowa
Concerning...Severe potential...Watch unlikely
Valid 162326Z - 170130Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms may gradually intensify as they move
southeastward into western IA. Storms may pose a hail and damaging
wind risk if intensification can occur, but a watch is not expected.
DISCUSSION...Thunderstorms moving southward across southwest
Minnesota have shown periods of intensification over the past 30-60
minutes. Specifically, a few stronger updrafts have been noted via
cloud top cooling and a corresponding concentrated uptick in
lightning. However, these trends have been rather brief, and
reflectivity signatures have largely remained unchanged. This
suggests that any meaningful intensification may be gradual over the
next few hours as the cluster of storms moves to the south/southeast
along an instability axis and into an environment with better
deep-layer shear. Recent RAP mesoanalysis estimates show 40-50 knots
of effective bulk shear oriented along the instability gradient in
place across western IA, which will continue to support clusters to
linear modes. If intensification occurs, updraft pulses may pose a
hail risk, and a more organized wind risk is possible if cold pool
amalgamation can occur. Given the uncertainty in the overall
potential threat from these storms, a watch is not expected.
..Moore/Guyer.. 06/16/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MPX...DMX...FSD...OAX...
LAT...LON 43469659 44069656 44449617 44489569 44309514 43779473
43239444 42649407 42299413 41999438 41819485 41779548
41769585 41819613 42159630 42919654 43469659Nearby
Mesoscale Discussions in Iowa, 2021Mesoscale Discussions in Minnesota, 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.