February was stormy, wet, and cold in Illinois

[March 05, 2019]    February was particularly cold and stormy in Illinois, with an almost constant succession of storms resulting in moderate snow accumulations for the northern counties and persistent rain events and widespread flooding for the far southern counties.

The preliminary average statewide precipitation was 3.33 inches, which is 1.27 inches above the long-term average, according to Brian Kerschner, spokesperson for the Illinois State Climatologist Office at the University of Illinois’ Illinois State Water Survey.

Locations in the center of the state, roughly between I-80 and I-70, received from 1.5 to 4.0 inches of precipitation for February, but the most impressive totals fell in far northwestern and in southern Illinois. The precipitation corresponded to monthly totals of 300 to 400 percent of normal for northwestern Illinois and 200 to 300 percent of normal for southern Illinois.

February precipitation totals in excess of 6.0 inches were common in southern Illinois, with five stations reporting over 8.0 inches of precipitation for the month. The highest monthly total was reported at Smithland Lock and Dam (Pope County) with 10.68 inches. This ranks as the wettest February on record for the station, with records going back to 1981.

Abundant regional February rainfall also contributed to major flooding in the lower Ohio River. Both the Smithland Lock and Dam and Cairo river gauges crested at over 10 feet above flood stage during the last week in February. Maximum river stages are expected to be within the top 5 highest on record, according to data compiled by the National Weather Service.

Statewide, February ended colder than the long-term average. The preliminary average statewide February temperature was 28.6 degrees, which is 2.3 degrees below the long-term average.

Overall, southeastern Illinois saw temperature departures averaging 1 to 3 degrees above normal, while much of central Illinois was near the long-term average, and a larger region of northwest Illinois saw temperature departures averaging 2 to 5 degrees below normal.

The highest February temperature of 70 degrees was reported at two stations, Dixon Springs (Pope County) on Feb. 3, and Kaskaskia River Lock (Randolph County) on Feb. 4.

These temperatures occurred less than a week after the historic Arctic outbreak in late January, which shattered numerous all-time station and daily record lows across Illinois. Over the course of five days, many stations across the state saw temperature differences of 70 degrees or more from Jan. 31 to Feb. 4.

The lowest state temperature was -36 degrees, reported at the Mt. Carroll observation station (Carroll County) on Feb. 1, a day after the station recorded a potential record state minimum temperature of -38 degrees on the last day of January 2019.

Snowfall occurred statewide during February, but was most plentiful in counties along the Illinois/Wisconsin border, where 10+ inches of accumulation were common. The highest snowfall total of 25.7 inches was reported at a station in Galena (Jo Daviess County).

Looking ahead at the rest of March 2019, the Climate Prediction Center is favoring moderate probabilities of colder than average temperatures statewide. The highest probabilities are located in the northwestern portion of the state. Slightly increased probabilities of a wetter than normal March are forecast for extreme southern Illinois, the same regions that have already experienced unseasonably wet conditions for most of the winter.

[Lisa A. Sheppard]