Problematic snow today (?) followed by big snow Monday and then extreme cold

We recorded a -8F (preliminarily) at ORD this morning. That is the first subzero low of the season and the first since Feb. 5, 2018.  We are not likely to record the rare feat of a subzero high temp today, but we may get one next week (see below).

 

Don’t let the beautiful, cloudless sunrise fool you – we could get ½ to maybe 1-2 inches of snow this afternoon and evening. This didn’t look like much, but it now seems that there will be just enough “lift” and just enough moisture to get some accumulating snow starting in the 3-5pm range. Areas north of the Eisenhower *could* miss out on the snow, and the snow *could* start after the commuting peak, but I wouldn’t plan on either if you need to be somewhere in a timely fashion tonight. The snow will be light and fluffy given the extreme cold, but the other result of the cold  is that salt is only marginally effective – any snow that does fall will stick on the roads. We all know that even a light snow during peak commuting times can create gridlock on the roads, so be advised.

 

Big snow on Monday? I will send an update on Sunday morning, but for now I would plan on a significant and disruptive snow on Monday. The early (low-confidence) over/under is six inches, starting late Sunday and going most of the day on Monday. Leading into the snow on Sunday night and Monday temps will be cold (single-digits up to the low 20s) and that won’t help the road conditions on Monday.

 

Extreme cold Tuesday-Thursday? We are looking at potentially historic cold next week. Details are tough at this distance, but there has been remarkable agreement for days on a major inflow of polar air beginning Tuesday. Model temperatures at altitude from the Dakotas, Minnesota, Nebraska, Iowa, Missouri, Wisconsin, Illinois, Michigan, Indiana and Ohio are showing levels seen once or twice in the ~40 years we’ve had satellite data.

• Wednesday is shaping up to be the coldest day since 1996. A decent guess right now would be a low around -16F and a high around -4F. If so, -16F would break the record low for Jan. 30^th (set in 1966 at MDW).***
• As noted in my last email, a temp below -15F is very, very rare in Chicago (~one per 1,850 days, or ~two per decade).
• If we do get a subzero high next week, it would be extremely rare. There are only 64 days on record* that failed to break 0F – that’s once every 2-3 years. We haven’t had many in recent years – just three in the past 25 years (-2F on Jan. 6, 2014,  -1F on Jan. 15, 2009, and -5F on Feb. 3, 1996). The all-time record-low high temp was -11F on Christmas Eve 1983.

 

 

Here is your evergreen reminder that we do not speak of wind chill values around here. You have different skin, hair, body fat, and clothes than your uncle Jerry and your Meemaw and everyone else, and even if you don’t, it’s still a bad idea to assign numbers based on a pseudo-scientific “formula” that was completely overhauled in 2001 and is still not based on anything resembling science but is somehow afforded credibility when generating numbers that are conflated with actual temperatures (the physical quantity that expresses hot and cold by measuring thermal vibration at the molecular level) and generally bastardizing meteorology in every possible way. Wind chill is to science as that last sentence is to good writing.

 

 

*** Here is your periodic reminder that Chicago’s official temperature records date to 1872 but have been recorded in four very different locations: the Loop, Hyde Park, Midway, and (since 1980) O’Hare. Compare with care.

 

 

 

 

 

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