Above Normal Rainfall and Snowfall
With the exception of a band stretching from Iowa to central Michigan, precipitation was above normal for the Midwest during the first week of April (Figure 1). Precipitation was 300% to 750% of normal across south and central portions of the region, as well as further north in northern Minnesota, northern Wisconsin, and northern Michigan. Total precipitation ranged from a low of 0.01" to 0.1" in southern Wisconsin to a high of 4" to 6" in central Missouri, southern Illinois, southern Indiana, and northwestern Kentucky (Figure 2). The high precipitation totals in the south and central Midwest fell during an event on April 2nd and 3rd, when a strong storm system (Figure 3) made its way across the Midwest, bringing localized heavy localized rainfall to Missouri, southern Illinois, southern Indiana, and northwestern Kentucky (Figure 4).
While heavy rainfall was falling in the south and central Midwest on April 2nd and 3rd, the same storm system brought heavy snowfall to the upper Midwest
(Figure 5). Portions of northern Minnesota and Upper Michigan received 12" to 18" of snowfall during this event. These snowfall totals were 2" to 16" above normal for this time of year (Figure 6). At the end of the first week of April, snow depths remained 1" to 30" across the upper Midwest
Below Normal Temperatures in Many States
Average temperatures were below normal throughout Minnesota, Wisconsin, Michigan, Iowa, and a majority of Missouri and Illinois (Figure 8). The greatest departures of -6°F to -8°F below normal were in Minnesota, northwest Wisconsin, and west-central Iowa. Indiana had a mix of below normal (northern Indiana), near normal (central Indiana), and above normal (southern Indiana), while much of Ohio was near normal and Kentucky was above normal. Departures in Kentucky ranged from +1°F to +3°F above normal.
Watch for Last Spring Freeze Continues
The spring season represents the transition in the Midwest from regular freezing temperatures in the winter to above freezing temperatures in the late spring and summer. The median dates for last spring freeze in the Midwest range from April 1st-10th in southern portions of the region to May 21st-31st in the upper Midwest (Figure 9). In years when the last spring freeze occurs earlier than normal, the dates for last freeze range from March 21st-31st in the southern Midwest to May 11th-20th in the upper Midwest (Figure 10). Finally, in years when the last spring freeze occurs later than normal, the date for last freeze range from April 21st-30th in the southern Midwest to June 11th-20th in the upper Midwest (Figure 11).
As of the first week of April, freezing temperatures are still occuring in the region as seen on this map which shows the date of the most recent 32°F freeze (Figure 12). Much of the region experienced freezing temperaures sometime during the first week of April, while some places further south have not had a freeze since the week of March 21st-31st. According to local vegetation experts, vegetation has started blooming in some portions of the Midwest, mainly Missouri and Kentucky, so the monitoring of freezing temperatures is important since freezing temperatures could damage growing vegetation. The last spring freeze can be monitored on the MRCC's Climate Watch page or on the Frost/Freeze Guidance Project webpage, which is part of the MRCC's Vegetation Impact Program.
The storm system that brought heavy rainfall and snowfall to the Midwest on April 2nd and 3rd also produced some severe weather as well (Figure 13). There were quite a few hail reports in Missouri, Illinois, Iowa, and Kentucky and high wind reports in the same states as well as Ohio. There were also 13 tornado reports in Missouri and Illinois. The reported tornadoes in Missouri and Illinois produced minimal damage, including minor damage to homes, overturned small structures, snapped tree branches, debris on roads, and fences blown down.