Alert archive / Iowa / Mesoscale Discussions in 2021
Mesoscale Discussion 126
The Storm Prediction Center issued this mesoscale discussion at Feb 21, 2021, 8:52 AM CST for 32 counties in Iowa; Burt County, Douglas County, Washington County, Nebraska. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 21, 2021, 8:52 AM CST (14:52 UTC)
- Expired
- Feb 21, 2021, 1:15 PM CST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Heavy snow
All 35 counties
Adair County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Buchanan County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Crawford County, IA, Dallas County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Harrison County, IA, Iowa County, IA, Jasper County, IA, Linn County, IA, Madison County, IA, Marion County, IA, Marshall County, IA, Monona County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Warren County, IA, Webster County, IA, Burt County, NE, Douglas County, NE, Washington County, NE
The radar
The Des Moines radar (KDMX), 28 km from the middle of the area, began a volume at 14:50 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, 2.9 hours before the alert went out and 197 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
- 590 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 184 m²/s²
- 0-3 km storm-relative helicity
- 201 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
766
ACUS11 KWNS 211453
SWOMCD
SPC MCD 211452
IAZ000-NEZ000-211915-
Mesoscale Discussion 0126
NWS Storm Prediction Center Norman OK
0852 AM CST Sun Feb 21 2021
Areas affected...I-80 corridor in Iowa
Concerning...Heavy snow
Valid 211452Z - 211915Z
SUMMARY...Bands of heavy snow possible within the I-80 corridor.
Heaviest rates will generally be near 1 in. per hour and will
diminish by 2-3 PM CST.
DISCUSSION...A strong mid-level shortwave trough and strong 700 mb
warm advection has led to bands of heavy snowfall in the Omaha, NE
vicinity. A band of heavier snow is currently ongoing to the west of
Des Moines moving northeast. As this system tracks to the east
today, heavy snowfall will continue to be possible along and north
of the I-80 corridor today. Peak snowfall rates of around 1 inch per
hour with isolated heavier rates are expected to occur within the
next 4-5 hours. Thereafter, lift within the dendritic growth layer
and 700 mb warm advection become more diffuse and snowfall rates
should decrease.
..Wendt.. 02/21/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DVN...DMX...FSD...OAX...
LAT...LON 41229606 41519644 42049635 42479473 42729318 42559177
42149148 41689174 41399236 41349290 41259366 41199474
41209541 41229606Nearby
Mesoscale Discussions in Iowa, 2021Mesoscale Discussions in Nebraska, 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.