Between Friday and today, the first of two significant late November arctic shots are bringing a distinctly December-like feel from the Dakotas all the way to Central Florida.

The core of the cold was over the Upper Midwest Friday with highs only managing 10° in the Dakotas and by Saturday morning, as the cold air slide east as well as south, much of Northern Minnesota woke to subzero territory for the first time this season. Babbit, MN was the nations ice box yesterday morning with a low of -10° while International Falls fell to -7°. This cold came following a 6-12 inch snowstorm up across the Arrowhead. While not as cold, it was no picnic in Minneapolis with a morning low of 10°, the average is 22°. The high on Friday was a chilly 27°.

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While highs rose between Friday and Saturday across the Dakotas and Minnesota thanks to a warmer south wind and increase in clouds with Minneapolis topping out at a more pleasant 30°, the core of cold sank southeastwards. Chicago only warmed to my forecasted high of 32° Saturday, again the models underdoing how cold the air was that was dropping out of Canada. The Twin Cities for example was forecasted to drop Friday night into Saturday to around 16° at lowest and indeed it fell to 10°. Northern Minnesota was expected to fall to low single digits and of course it was widely between -5° and -10°.

During Saturday, the arctic boundary continued diving southeast and this forced the issuance of freeze warnings all the way to the Gulf Coast and into central Florida.

Here are the lows this morning!

Temperatures fell into the mid to high teens in the North Georgia and Carolina mountains. I noticed a few 17°, 19° readings, so it was a very cold late November night and these numbers wouldn’t be sniffed at even in mid winter down in these parts.

The cold, while easing while be immediately followed by a second lobe of arctic air which not only will be stronger with colder temperatures expected across the Northern Plains, Midwest, Ohio Valley and East Coast but we are likely to see a stormdeveloping on the south side of the trough and this will slide east, intensifying into an East Coast storm which could paste the Northeast in a heavy blanket of snow.

Here is the ECMWF charts for the next wave of cold.

Tonight will see the leading edge of this next batch of cold sweep in the northwest with the eastern Montana and North Dakota cooling through this afternoon and especially tonight, it goes comfortably below zero. Comfortably isn’t the right word I guess to use but you know what I mean.. How cold? Many will go below zero with northern parts perhaps dropping to between -10° and -15°, and Northern Minnesota between 0° and -12°. Minneapolis may get below 10°, making it their coldest morning too. However, this next shot appears to push in and out pretty quickly with warming already beginning tomorrow over eastern Montana and the western Dakotas but further east, highs may fail to crack 10 from Minot to Rhindelander, Wisc on Monday.

Minneapolis could stay below 20° for the first time during November in some 4 years.

Monday

As you can see, the second lobe doesn’t appear to extend as far south as the current one, so this suggests a stronger ridge underneath which keeps it milder across a large chunk of the country including the South but where the cold air does run across, it will be colder.

Will There or Won’t There Be A Snowstorm Tues, Tues Night?

As this second cold wave comes south, a piece of energy riding the jet, develops a low pressure system down near where Virginia meets North Carolina. Where potential snows and or rain falls will depend upon where this system develops and then tracks. The ECMWF continues to show barely anything while the GFS has a system developing and sliding off the coast, south of Washington DC. Initial modelling had this system riding the jet northeast via the eastern Great Lakes but without looking at any model, this was hard to buy considering how negative the NAO was going. The negative NAO would favour more of a trough further east which would take the storm to the coast. But does it head due east off the Mid-Atlantic coast which would leave, perhaps even Philly and certainly NYC and Boston dry or does it track further east duut across or just north of the Big Cities? If that occured there would be just rain for the cities.

The GFS in recent runs has been trending towards a Philly to Boston snow event and I believe a 2-4, locally 6 inch swath is possible with snows reaching the coast as the storm exits and colder air draws in.

Here’s the latest GFS 1000-500mb thickness chart.

Tues 48 hrs

54 hrs

Notice the crucial 540 height line stays SOUTH of Philly and right over DC, this may mean more of a rain changeover to snow event for DC while I recon Philly, NYC and Boston see all snow but Boston. Temps may hover right on the cusp though at 34, falling as the precip pushes through and evaporative cooling takes place.

Snow at 48 hrs

54 hrs

57 hrs

Back to the cold of the second arctic shot. Here’s Tuesday according to the ECMWF.

Tuesday

Wednesday

 

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