The first snow of the season is blowing across parts of the Midwest, the Great Lakes and the Northeast to end the week, while a reality check pattern change in November is bringing cold air as far south as Texas and Florida.

Snow setup: A powerful low-pressure system has developed over the Great Lakes region. This storm could continue Friday or Saturday, bringing strong winds, raw, cold air, rain and sleet.

In the radar snapshot below, you can see where that storm is currently producing snowfall and rain. Chicago, Detroit, Milwaukee and Indianapolis are among the cities that saw their first snow of the season Wednesday night into Thursday morning.

The National Weather Service has issued several winter weather warnings for snow from the Great Lakes to the Appalachians and the Interior Northeast.

In general, any snow falling in the Great Lakes and Ohio Valley will do so through Thursday evening. Anyone falling in the east will do so Thursday through Friday evening or Saturday.

(For even more detailed weather tracking in your area, view your detailed 15-minute forecast in our Premium Pro experience.)

How much snow: We do not expect widespread heavy accumulations. However, the higher elevations of the Appalachians from West Virginia to southwestern Pennsylvania, as well as the Poconos, Catskills and Adirondacks, could receive 6 inches or more of heavy, wet snow.

The weight of this snow and high winds could cause tree damage and power outages in those areas.

Otherwise, muddy amounts of several inches are possible from the Great Lakes into the Ohio Valley and lower inland parts of the Northeast. Most of these accumulations will be on lawns and vehicle roofs unless the snow comes in a quick burst or downpour, which could cover some bridges and untreated roads.

Colder, finally: The South hasn’t felt like winter is just around the corner lately. Instead, the region saw the warmest first two weeks of November on record for dozens of cities from Texas to Florida and the southern Appalachians, according to the Southeast Regional Climate Center.

And that is where the coming reality check will be most felt.

This colder air should move quickly over the rest of the South, lower Midwest and East on Thursday. It will likely linger in the Southeast through the weekend.

We have some examples of predicted low temperatures on the map below. Lows in the 30s and 40s will be common across the South, possibly in parts of North Florida. Peninsula Florida may see some cold mornings in the 40s and 50s. Meanwhile, highs in the 40s and some 30s will be the rule across the Midwest and Interior Northeast through the end of the week.

(​CARDS: 10-day US forecast highs and lows)

Why this pattern change: The short answer is that the wind flow in the atmosphere becomes temporarily blocked.

A bubble of high pressure in the sky known as the Greenland Block is acting as a temporary roadblock, forcing a deep low-pressure system to become trapped over the east.

That’s why this storm system and the cold air in the east could last for several days.

Jonathan Erdman is a senior meteorologist at Weather.com and has been covering national and international weather reports since 1996. Extreme and bizarre weather are his favorite subjects. Contact him X (formerly Twitter), Wires, Facebook And Blue sky.