Areas of Severe Thunderstorms and Excessive Rainfall Friday

Severe thunderstorms capable of large hail and damaging wind gusts appear possible over the central and southern High Plains and eastern Kansas into Missouri Friday afternoon and evening. Rounds of storms Friday ahead of a slow moving frontal boundary will bring locally heavy rainfall and scattered flash flooding potential to the Mid-Mississippi, Ohio, and Tennessee Valleys, and the Appalachians. Read More >

Event Overview

A spring snow storm (or late winter storm) brought a heavy band of wet, sticky snow to central and southern Iowa on the evening of Thursday, April 16 to the early morning of Friday, April 17, 2020. A sharp gradient of the snowfall setup and generally Interstate 80 was the cutoff of the heaviest snowfall to the snow and lighter amounts to the north. North of I-80, reports ranged from trace to around 4 inches, which 3-4 inches was common in the Des Moines Metro. Further south, especially the two rows of counties in far southern Iowa, had a band of 8-12 inches with a few isolated higher snowfall reports in Wayne, Decatur, Ringgold, and Taylor Counties. The snow stuck to trees, bushes, power lines and made for some amazing photos across central Iowa. Sunshine quickly melted off the snow later Friday morning and into the afternoon hours and all the snow except a small batch across southern Iowa had melted off by the time the sun set Friday night.

Accumulated snowfall across Central and Southern Iowa from April 16 to the morning of April 17, 2020.


Murray, IA. Photo courtesy of Gregory Clark	Lamoni, IA. Photo courtesy of Alex Pickman via Twitter	Chariton, IA. Photo courtesy of Greg Watsabaugh via Twitter

Photos & Video
Satellite and Radar
Storm Reports
Environment

Photos & Video

We received over 250 photos of some of the most picturesque snow that Iowa has seen in sometime. Most of these photos can be found on Facebook or Twitter. Thank you to all that provided us with these great photos!


Lamoni, Iowa. Photo courtesy of Basehunters Chasing via Twitter	Photo taken on the morning of April 17th at the NWS office in Johnston, Iowa	Van Horne, Iowa. Photo courtesy of Amanda Hutton	Along I-35 south of Des Moines. Photo courtesy of Amarie Crooks.


Council Bluffs, Iowa. Photo courtesy of Debi Derry Sell	Newton, Iowa. Photo courtesy of Corki Speck Stokka	Unknown Location. Photo courtesy of Gayle Ramaeker	Ottumwa, Iowa. Photo courtesy of Curtis Woten


Before and after snow melt in Anita, IA. Photo courtesy of Alissa Mixon Fountas	Earlham IA. Photo courtesy of Ashley Petersen	Leon, IA. Photo courtesy of Jennifer Watson	Photo courtesy of Sarah Summers in Marshalltown, IA.


The famous Cedar Bridge in Winterset, IA. Photo courtesy of Laraine Magee Davis	Sun Valley Lake near Thayer, IA. Photo courtesy of Lindsey Joy	North of Hedrick, IA. Photo courtesy of Lynette Chittick	Winterset, IA. Photo courtesy of Michelle Webb


Ankeny, IA. Photo courtesy of Erica Aleman	Promise City, IA. Photo courtesy of Shawna Hopkins	Near John Deere Plant in Ankeny. Photo courtesy of Ron Feigl	Unknown location. Photo courtesy of Brenda Howington


McCallsburg, IA. Photo courtesy of Rebecca Jeanne Sittig	Swedesburg, IA. Photo courtesy of Scott Deaton	Unknown location. Photo courtesy of Amy Gaumer	Ottumwa, IA. Photo courtesy of Rosanne Marie Woods

Radar and Satellite


Radar loop of event event starting at 1 PM on Thursday, April 16 and ending at 9 AM Friday morning, April 17. Images courtesy of IEM	The visible satellite RGB band called Day Cloud Phase Distinction via GOES-East. 1-minute data on Thursday afternoon when the snow band developed over southwest Iowa and eastern Nebraska.	Visible GOES-East Channel 2 shows the end of the snow pack melting on Saturday, April 18, 2020.	Another color curve on the GOES-East visible satellite showing the snow melting over portions of Nebraska and western Iowa. The red is the snow pack, while cloud cover is the white moving east.

Storm Reports

There are multiple ways to view the snowfall reports gathered from the event. Click on the links below:

https://nwschat.weather.gov/lsr/#DMX/202004162330/202004171600/0100

https://nwschat.weather.gov/p.php?pid=202004171622-KDMX-NWUS53-LSRDMX

https://www.weather.gov/source/crh/lsrmap.html?zoom=7&lat=39.92&lon=-92.74&hr=72&severe=1&winter=1&flooding=1&tropical=1&other=1

Environment

A strong low pressure system tracked across southern Nebraska/Northern Kansas into Missouri Thursday (4/16) into Friday (4/17) and placed Iowa within the colder air of the system. Abundant moisture, strong lift within the snow growth zone, and temperatures below freezing throughout the column led to a wet, sticky snow across central and southern Iowa.


Omaha observed sounding from 00z April 17 shows the deep saturation and the surface temperatures just below freezing resulting in a wet, heavy snow.	WPC surface analysis Thursday into Friday.	500 mb upper air analysis

Strong frontogenetical forcing and lift within the dendritic layer, resulted in snowfall rates of 1 to 2 inches per hour across southern Iowa Thursday night, April 16th.


850 mb Petterssen frontogenesis shows strong frontogenetical forcing in northern Missouri and southern Iowa during the late afternoon into the evening hours Thursday.	700 mb Petterssen frontogenesis shows strong frontogenetical forcing in northern Missouri and southern Iowa during the late afternoon into the evening hours Thursday.	85mb Frontogenesis (red lines), 800-750 mb Equivalent Potential Vorticity (EPV - shaded) and Conditional Instability (CI-black). When negative EPV is present and thus CI, increases potential for heavy banded snow.

Additional environmental data.


Dendritic Layer RH and Omega shows saturation and strong lift within the dendritic (-12C to -17C) layer, which supports intense snowfall rates.	850 mb SPC mesoanalysis at 7 p.m. CDT Thursday, April 16th when the snow band increased in intensity.	Mean sea level pressure, surface dew points and winds during the entire event

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Areas of Severe Thunderstorms and Excessive Rainfall Friday

April 16-17, 2020 Heavy, Wet Snow Across Central to Southern Iowa