Midwest Weekly Highlights - February 15-21, 2014

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Above Normal Precipitation for Majority of Midwest

Precipitation was above normal for a majority of the Midwest during the third week of February, with the exception of southwest portions of the region and western Minnesota (Figure 1). Portions of Minnesota, western Wisconsin, Iowa, and western Illinois experienced precipitation that was 500% to 750% of normal. Weekly totals of at least 1" were widespread throughout the region, with 1.5" to 2.5" falling across portions of the central Midwest and in Kentucky (Figure 2). Much of this rain fell during events on February 17th (Figure 3) and another that spanned February 19th-20th (Figure 4) (see below for more information on this event).

While some of the precipitation that fell during the week came in the form of rainfall, a majority fell as snow, especially in the upper Midwest. Snowfall totals ranged from 0.1" across southern portions of the region to 15" to 20" in the Lake Superior region of Minnesota and Wisconsin (Figure 5), much of which fell during the February 19th-20th storm event (Figure 6). The highest snowfall totals in Minnesota and Wisconsin were 10" to 17.5" above normal for this time of year (Figure 7).

Mix of Above and Below Normal Temperatures

There was a mix of above and below normal temperatures in the Midwest during the third week of February. Northeast portions of the region experienced temperatures that were 1°F to 7°F below normal, while areas to the southwest were above normal by 1°F to 6°F (Figure 8). The week started with two very cold days (Figure 9), followed by a unseasonably warm last four days of the week (Figure 10). The region got a little relief from the cold winter as temperatures peaked on February 20th (Figure 11), with high temperatures reaching at least 50°F for the southern half of the Midwest (Figure 12).
 

February 19th-20th Storm Event Summary and Impacts

A very dynamic storm system impacted the Midwest on February 19th-20th (Figure 13), producing everything from winter precipitation, to severe thunderstorms, flash flooding, and dense fog. Not only did this event produce significant precipitation of various types, but also brought much warmer temperatures to the region. The warmer temperatures quickly melted much of the snow that was on the ground before the storm (Figure 14). New rain also fell in addition to this rapidly melting snow, making flash flooding an issue across the region. Streamflow of rivers across portions of the Midwest were much above normal following this event (Figure 15), with several above flood stage as of February 24th (Figure 16). Also, with a much more warm and moist air mass associated with this storm system, the combination of the melting snow and rapidly increasing moisture resulted in the development of very dense fog. The Chicago NWS reported dense fog producing near-zero visibilities for a few hours on February 20th.

The warmer temperatures also broke up ice cover on rivers around the Midwest, with the significant runoff causing the ice to float downstream. The movement of the ice on the rivers led to what are called "ice jams" across the region (Figure 17). Ice jams occur when the river channel is constricted and can result in erratic river levels, as well as significant flooding near the site of the jam. Areas in the Midwest impacted by ice jams and the resulting flooding issues included the Wabash River between Carroll and Cass counties in Indiana, Coshocton County in Ohio, the Kankakee River in Illinois (affecting Kankakee, Will, and Grundy counties), and the Vermillion and Chagrin rivers in Ohio (affecting Erie, Lorain, and Lake counties).

Finally, this storm system also brought numerous severe weather reports to the Midwest on February 20th, including 23 preliminary tornado reports in 16 counties across the region (Figure 18). Initial reports discuss that tornadoes were fairly weak (EF0 to EF1), resulting in minimal damage like damage to buildings, livestock, and minor injuries after a mobile home overturned and landed on a vehicle. There were several high wind reports, the highest of which was 75 mph reported in Marion, IN (Grant County). Wind damage across the region included the downing of large trees and power lines, shingles blown off of buildings and other structure damage, and overturned high profile vehicles on highways.

-MW-