Bolaris: Finally time to break out your winter coats

20140217_snowfall_600
Snow covers the walkway alongside the Benjamin Franklin Parkway on Feb. 13, 2014. (Colin Kerrigan / Philly.com)

The atmosphere is about to go Jekyll and Hyde on us.

Veterans Day should be another gem as temperatures climb close to 70 degrees in some places and the unseasonably mild temperatures will spill into Wednesday too. But...

Last week, I wrote about how Typhoon Nuri would transform into a non-tropical beast as the former typhoon moved into the Bering Sea and how this would set off an atmospheric domino effect that displaced the polar jet stream. The jet stream takes a big dip south, opening the door for the coldest air mass of the season to enter the United States. Thus...

The Bering Sea storm did become the strongest storm ever in the North Pacific and the atmospheric chain of events has been put into motion. So...

First up: A raging snowstorm dumps as much as 18 to 24 inches of snow across the Upper Midwest and Arctic air sends temperatures some 25 to 35 degrees below normal across the Plains and portions of the Midwest.

The same trough that sends temperatures plunging in the West pumps up unseasonably mild air across most of the east out ahead of the approaching Arctic front.

Next up (and what it means for us): Arctic air starts to arrive in the Philadelphia region late Thursday. Temps will tumble Thursday night and bring in the chance of seeing our first flakes in the city — either very late Thursday night or early Friday morning. Flurries and or snow showers are in my forecast.

Friday will be windy and very cold with temperatures ranging between 39 and 43 degrees.

Next Monday: A storm could clip us with a wintry mix for some.

Next Thursday: Possible winter-type storm. 

Alas, the atmosphere is about to switch into a winter mode and whether or not we get significant frozen precipitation, I guarantee that your winter coat will be your best friend starting Thursday night through next week.