Temperatures/March Warmth

Temperatures were well above normal for the entire region (Figure 1). Average temperatures were 10-15°F above normal for most of the region, with the exception of Michigan’s UP and the Kentucky Coalfields. In Eau Claire, Wisconsin, the mean temperature on March 14 was 61.5°F, which was the warmest in March since 2012 and the earliest in the calendar year. In Minneapolis, a mean temperature of 61.5°F was observed on March 14, which was the warmest since 2012 and earliest in the calendar year since records began in 1871.

Minimum temperatures were less anomalous. Most of the region observed minimum temperatures that were 4-8°F above normal (Figure 2). In Minnesota, minimum temperatures were upwards of 10°F above normal. Waterloo, Iowa observed a minimum temperature of 53°F on March 14, which was the warmest minimum temperature in March since 2012 and the earliest in the calendar year since records began in 1895.

Maximum temperatures averaged as much as 20°F above normal for the week (Figure 3). A strong warm front associated with a low-pressure system anchored over the Great Plains brought maximum temperatures into the 70s and 80s for parts of the region by the end of the period. Peoria, Illinois, observed a temperature of 82°F on March 14, which was the warmest March temperature since 2012. In Muskegon, Michigan, the temperature rose to 79°F on March 14, which was 35°F above normal and the earliest ever recorded in the calendar year since 1896. Madison, Wisconsin observed its warmest March temperature 2012 as the mercury rose to 78°F on March 14, which also tied March 14, 2012 for the earliest in the calendar year. As a result of this, Lake Mendota and Lake Monona—the two lakes surrounding Madison—became ice-free 15 days earlier than normal, according to the Wisconsin State Climatology Office.

Precipitation/Drought

There was almost no precipitation anywhere in the region this week (Figure 4). At best, parts of Iowa and northwestern Illinois observed 25-50 percent of normal precipitation. Any precipitation that did fall was associated with the warm front that dominated toward the end of the week.

By March 11, snow and rain during the prior week helped eliminate some D0 (abnormally dry) and D1 (moderate drought) conditions from Illinois, Iowa, Minnesota and Missouri (Figure 5). Some D2 (severe drought) was added to east-central Illinois. Most of the Upper Midwest remained unchanged with colder and drier conditions in place during the prior period.

March 13-15 High Winds/Severe Weather

A sprawling low-pressure system induced high winds across the region beginning late on March 13 and continuing for much of the day on March 14. Non-thunderstorm wind gusts of 40-55 mph were reported across the Midwest on March 14. Strong winds and dry conditions ahead of the low-pressure system aided in the spread of wildfires, triggering Red Flag Warnings in the Quad Cities area.

Thunderstorms came later in the day. Lightning struck a field of timber in Johnson County, Iowa, igniting a fire that spread for 25 acres. In Illinois, an EF-2 tornado near Neoga crossed I-57, injuring two semi-truck drivers. Preliminary findings indicated at least 6 tornadoes touched down across the National Weather Service (NWS) Central Illinois’s forecast area. The NWS in Indianapolis confirmed five tornadoes early in the morning on March 15 across Central Indiana, with an EF-1 in Parke County damaging a 150-year-old barn.

The most hard-hit region was in southern Illinois and southeastern Missouri, both of which are covered by the NWS in Paducah, Kentucky. Four separate EF-3 tornadoes were reported, including one in Poplar Bluff, Missouri that caused three injuries and one death. Some homes were completely leveled. The Poplar Bluff Tornado was on the ground for 18.7 miles and had peak winds of 145 mph. Some of these tornadoes spent 30-40+ miles on the ground. As a result, NWS Paducah confirmed at least 183 miles of tornado damage, the second most from a single event in their forecast area. In total, over 700 storm reports were made this week, with the vast majority being wind (440) and hail (220), though there were 45 tornado reports mostly across Missouri, Illinois, and Indiana (Figure 6).