Roosevelt Severe & Unusual Weather: Arctic Blast: Lake-Effect Snow Breaks Out as Frigid Air Plunges South

Tuesday, November 12, 2013

Arctic Blast: Lake-Effect Snow Breaks Out as Frigid Air Plunges South

(MAPS: Current Temperatures | Current Wind Chill)

The jet stream is currently taking a sharp plunge south from Canada across the eastern third of the country. This jet stream dip is accompanied by a chilly, expansive and very strong area of high pressure at the surface that can be traced back to the Arctic. The barometric pressure was as high as 1048.5 millibars (30.90 inches of mercury) at Lincoln, Neb., early Tuesday morning.

This pattern change is leading to a widespread area of well-below-average temperatures. Let's take a closer look at the colder forecast details and see how much snow will be squeezed out.

(NOW: Latest Winter Weather Updates)

The Cold

ge Wednesday

Temperatures over 20 degrees below average in some cases will progress south and east to the Gulf Coast and East Coast through Thursday.

Wednesday (MAPS: Highs | Lows): As illustrated by the map to the right, temperatures will be up to 20 degrees below average over an expansive area from the Midwest to the Deep South and East Coast. Highs may hold in the 50s in parts of north Florida and the northern Gulf Coast. Morning lows in the 20s may plunge as far south as central Texas, northern Louisiana, and points east across the Deep South into the Carolinas. A few daily record lows may be threatened in parts of the Northeast (low-mid 20s) and Southeast (upper 20s to low 30s). Temperatures start to warm up for the High Plains.

Thursday (MAPS: Highs | Lows): Chilly weather lingers in the South, East, and Ohio Valley, though most areas will be slightly warmer than Wednesday by the afternoon. A morning freeze is likely across much of the Southeast, possibly including a few spots in the Florida Panhandle and the central Gulf Coast. A hard freeze (low to mid 20s) could reach as far south as middle Georgia, central Alabama and central Mississippi. Daily record lows are possible from parts of the Carolinas to Alabama (20s to near 30).

After Thursday, the coldest air will modify and retreat across the central and eastern U.S.

(MORE: Your Local Forecast)

Any Snow?

Wednesday's Forecast

While this time of year is notorious for major Great Lakes snowstorms, that's not what we're seeing with this moisture-starved Arctic cold front. Sorry, kids...no snow day.

(INTERACTIVE MAP: Where is the snow now?)

Winter Weather Avisories

Most of the snow with the cold front itself has ended as the front pushes south.

But behind the front, as bitter Arctic air rushes over the warm Great Lakes, lake effect snow has developed. Up to 14 inches of snow fell in extreme southwest Michigan around St. Joseph Monday night into Tuesday morning as a narrow but intense lake-effect snow band developed off Lake Michigan. That lake-effect snow band has dissipated.

Farther east, scattered lake-effect snow showers are expected southeast of Lake Erie and Lake Ontario for parts of northeast Ohio, northwest Pennsylvania, and western and central New York. With winds crossing nearly perpendicular to the lakes and a relatively dry source of Canadian air, the snow totals in these areas are expected to be light and manageable, on the order of a few inches at the most.

(INTERACTIVE: When Does First Snow Arrive?)

If you're seeing the first snowfall of the season where you live, we'd love to see your photos or video. Share them with us at weather.com/iWitness, post them to our Facebook page or tweet them to@weatherchannel.