Early Feb warm-up
The temperature is creeping up past 40F at this hour and should get at or just under 50F by mid-afternoon here in the Chicago-land area. A warm February day, indeed! The amazing thing is, once the thermometer goes above 40F it will probably not fall below 40 until late Tuesday night! That means tonight will be a warm, balmy night - with plenty of water to go around:
A storm is tracking across the center of the country. Southerly flow will push a warm front up and into the Chicago area later today. The warm front will be followed by a disorganized cold front late tonight, and the whole system should clear the area by tomorrow. A deformation zone behind the low could bring some low stratus and colder temps late Tuesday but probably nothing in the way of precipitation.
Before the associated cold front clears the area tonight, we could experience a period of scattered thunderstorms! The phasing of the upper-levels with the surface low is not perfect, and therefore there isn't a lot of upper support for big boomers, but should probably hear a few rumbles of thunder. Rain totals look to be on the order of 1/3 of an inch or so.
Here's the hi-res NAM showing simulated CAPE (a measure of the available convective [i.e. thunderstorm-producing] energy) during the frontal passage:
What you see is that much of the thunderstorm energy stays to our south.
High temperatures tomorrow could get up to 50 again if the clouds manage to clear out a bit.
Stay tuned :)