cold, then snow, then extreme cold

Well, after winter came early in November and then disappeared for all of December and the first half of January, we’re packing it all in to these three weeks…

 

A blast of cold air will arrive tomorrow, and by Friday we’ll be in the deep freeze. Friday morning should see our first official subzero temps of the season (long-term average is five per year, with 3-4 already on the books by now). Saturday will also be cold before Sunday moderates toward seasonal norms.

 

Late Sunday night into Monday could feature a significant snow. A classic-looking set-up is coming together and could bring several inches overnight Sunday through the day on Monday. Stay tuned – it’s way too early for details, but be on the lookout if snow on Monday morning would be a problem for travel plans, etc.

 

Following that potential snow on Monday, cold air looks likely to spill into the eastern third of North America. The graphic below shows a blob of frigid blue – the air that would normally be parked right above the North Pole – sitting on the Great Lakes. Some models are putting out numbers that are also cold as anything we’ve seen in decades, and numbers that have only been recorded a handful of times in 30-40 years. Again, it’s way too early to feel confident in any details. Just be prepared for the potential to see double-digit subzero temps on Wednesday (Jan. 30^th). One credible model is looking at -15F to -20F that morning. The second graphic shows the actual set-up on Jan. 6, 2014 – the original outbreak of the godforsaken term “polar vortex” – when Chicago recorded an official (and record-breaking) low of -16F. You don’t need a PhD in meteorology to see the similarities, but again, consider the pattern and odds, not the details, for now. For more context on how rare that would be:

 

• Chicago has only recorded 29 days of -16F to -20F – that’s 0.0005%, or roughly one out of 1,852 days, or about two days per decade. *
• There have only been 11 days of -21F or colder – that’s 0.0002%, or roughly one out of 4,762 days, or about two days every 25 years.**
• The daily record for Jan. 30^th is -15F (taken at MDW).***
• The ONLY January temperature record we’ve broken since 1985 was the -16F on Jan. 6, 2014.
• Other fun facts: since the brutal cold of some winters in the 1980s we have only set five daily cold records, and only one this decade:
• -16F on Jan. 6, 2014
• +4F on Dec. 5, 2005 (that one is begging to be broken!!!)
• -8F on Dec. 12, 2000
• -16F on Feb. 2, 1996
• -19F on Feb. 3, 1996
• If the daily average temp of ~8F verifies for Jan. 24-30^th it would rank as the coldest such period recorded at O’Hare since 1980

 

 

 

* Here is your periodic reminder that we do not speak of wind chill values around here. If you want the full rant just email me and I’d be glad to oblige.

 

** Chicago’s all-time record low was -27F at ORD on Jan. 20, 1985. Please don’t let people tell you otherwise, or conflate Satan’s plaything – also known as the wind chill – with actual temperatures.

 

*** Here is your other period 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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