It hasn’t been warmer here since early December! Monday’s official 53-degree high at O’Hare was not only the city’s mildest temp of 2014, it was the warmest reading here in the more than 3 months since Dec 4. It broke a string of 16 consecutive below normal days finishing 9-degrees above normal.
In a month running more than 12-degrees colder than normal, that was enough to send many in the area scurrying into the gusty but mild southwest winds which accompanied the warmth.
Warm as it was at O’Hare and with the 54-degree high recorded at Midway, several WeatherBug sites in the city fell just 2-degrees shy of 60-degrees.
Other area highs included 56 at Winnetka, Kankakee and Wheeling and 55-degres at Downers Grove, Orland Park and Libertyville.
Chicago’s official 53-degree high paled in comparison to St. Louis’ 80-degree warmth
Mild as it was in Chicago, it was downstate residents who were treated to the Heartland’s warmest readings.
Temperatures hit 80 at St. Louis. The warmth scuttled records at a number of Plains observation sites. Hill City, Kansas topped out at 79 as did Bartlesville, OK. 78-degree highs established new records at Lincoln, NE while Norfolk and Omaha registered 75 and 73-degree highs—each new records.
Storms thrive on huge temp spreads; the powerhouse jet stream winds these temp variations produce encourage strong “lift” which maximizes precipitation formation.
Huge variations in temperatures, like those observed across the nation’s mid-section Monday, set the stage for powerful jet stream winds which, in turn, help encourage the strong vertical motions which drop barometric pressures, encourage cloud and precipitation formation and lead to the development of strong winds which race moisture into strengthening storms.
Such a storm is Chicago-bound Tuesday night. The northeast winds on the intensifying spring storm’s northern flank will be strengthening slowly here during the day, sweeping into the city off the icy waters of Lake Michigan. It’s a development which will make short-order of any 40s recorded Tuesday morning.
Temps are expected to retreat to the 30s the remainder of the day—but the approaching storm’s real meteorological impacts are to take take place Tuesday night as cold rain reaches the city by late evening then mixes with sleet before shifting to heavy, possibly thundery snows toward and beyond midnight. The precipitation is to break out amid strong northeast winds likely to be gusting over 30 if not 40 mph late Tuesday night into Wednesday.
Tuesday night storm’s widespread 6-8” snowfalls could include thundery snowbursts generating locally higher totals
The combination of heavy snow, high winds and cold temps is to make for some real travel issues overnight which may spill into Wednesday morning.
A suite of computer model snowfall forecasts as well as other snowfall forecast techniques suggest widespread 6 to 8” totals are a good bet with possible bursts of thundersnow with the vigorous spring storm threatening local 10” totals by daybreak Wednesday.
The wildcard will be just how fast precipitation transitions to snow. The sooner that happens, the greater the potential accumulation. We’ll be updating forecasts Tuesday as the newer information arrived.