Late Dec-Jan Level Cold Dominates Eastern Lower 48 This Week, Snow In Unusual Places!

Written by on November 10, 2013 in United States of America with 0 Comments

We continue to look at the major arctic air mass and snow prospects coming up this week over the Midwest, East and even Southeast US.

While the snow has backed off considerably on the models from 3 or 4 days ago where both GFS and ECMWF had a major East Coast snowstorm, the arctic air is very much coming. Check out these 6am temperatures up over the heart of Northwest Canada this morning Via Ralph Fato.

Chart courtesy of Ralph Fato (@WeatherNut27)

Chart courtesy of Ralph Fato (@WeatherNut27)

As my weather friend Ralph (lives in Connecticut) correctly tweeted this morning, often you get a sense of what’s coming if you look up north and sure enough, that late December level cold will dive south with the help of a ridge building into Western Canada. Low pressure is sliding quickly east tonight into tomorrow and it’s as this system pushes into the Great Lakes, so the arctic front begins it’s southward journey en-route to the Gulf of Mexico.

The models I believe are on a much more realistic track with regards to snow and here’s the GFS snow chart through the next 48 hours.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Don’t expect snow COVER to be as widespread as this. We should see snowfall as the arctic front dives south but it’s won’t lie as widespread I don’t think. Could see a coating to an inch in Chicago, Indianapolis, Toledo and possibly Pittsburgh tomorrow night but moisture could be limited along the front.

Here’s out to 72 hours.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Note the blue tinge showing to the lee of the Great Lakes hinting at lake-effect while it’s also over a broader area of eastern Ohio, west Pennsylvania and West Virginia. That could be 1-3 inch accumulations with locally higher amounts in favoured upslope areas.

You’ll probably notice the model has it snowing all the way south past Atlanta.

Here’s a closer look at the Southeast.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

White on the chart generally suggests a coating at best or simply it’s hinting at snow in the air but not necessarily any accumulation. The mountains of North Carolina, perhaps Tennessee could conceivably catch 4-6 inches while the North Georgia mountains may be a couple of inches. As for Atlanta rain may turn to wet snow for a time but I don’t expect any sticking. That would be pretty rare to see this early for sure.

Let’s take a look at the surface charts to get a better handle of the cold coming south and precipitation.

Here’s the initial set which shows a low over the Ont-Que border, high pressure over Iowa-N Missouri and a low off the PNW coast while the arctic high is centred over central Alb-Sask border.

gfs_namer_003_850_temp_mslp_precip

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What will happen is low pressure will run the international border tonight and during the day tomorrow, will open the door for the high over west-central Canada to starting dropping south.

24 hours from now and you can see low pressure positioned over James Bay while the arctic high begins to drop into the Dakotas. The green presents moisture along the arctic front which will be producing snow. That snow band will head south with late December even January-level cold coming behind.

gfs_namer_024_850_temp_mslp_precip

By 48 hours (below) the arctic high has an impressive 1044 center over eastern Nebraska with the arctic front sweeping through the Appalachains producing snow which will likely be accumulating over the northern Ohio Valley and interior Northeast with 2-4 inches in the mountains of PA, MD, WV.

Note the green showing downwind of the lakes well behind the front.. that’s lake effect snow!

gfs_namer_048_850_temp_mslp_precip

By 60 hours the arctic high pretty much dominates everywhere east of the Rockies but note the embedded upper system showing green over the southern Appalachains, that’s the snow the model has for the mountains of NC, GA, TN.

gfs_namer_060_850_temp_mslp_precip

Don’t be surprised if the upslopes of North Carolina and Tennessee pick up 6 inches from that system.

By Thursday the high is positioned over the Southeast and the return flow is already starting the warm-up over the Plains and eventually through the Ohio Valley and Northeast.

gfs_namer_099_850_temp_mslp_precip

Just How Cold?

The cold will progress southeast starting tonight as it crosses into the Lower 48 and will probably be at it’s most intense and across the greatest area by Wednesday morning. In fact Wednesday morning will likely present plenty of record lows with a huge area of 25 to 35 below normal. More like late December and for the South, January!

Here’s tonight according to TWC

Source: weather.com

Source: weather.com

Tomorrow

Source: weather.com

Source: weather.com

GFS surface temps Tue AM

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Check out this chart from the NWS which shows the difference in Southern temperatures between Monday and Tuesday.

Courtesy of the NWS

Courtesy of the NWS

Here’s the GFS Wed AM temperatures.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Note the freezing line gets close to the Gulf Coast. We could see 12-19F through the Appalachians, 20-25 widely through the Mid-Mississippi and Ohio Valleys. Northern Alabama and Mississippi could drop to near 20 in spots. Upper 20s from DC to NYC, low 20s Boston, 10s for southern New England, 0s to -0s over interior New England.

Not any warmer and could even be colder in the South Thu AM.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Once the high pushes out into the Atlantic which is will by the end of the week into the weekend, warmer air returns for all.

Here’s the CPC temperatures in the 6-10 day.

610temp_new

CFSv2 also shows the warm-up which follows.

wk1_wk2_20131105_NAsfcT

Interestingly the CFSv2 shows warmth holding across most of the Lower 48 into December with major cold building over Canada. However, while I agree with the major cold building over Canada, one must wonder about the warmth holding over the US as the AO as well as NAO is due to go negative towards the end of the month. I wouldn’t be surprised if this model starts to turn colder for the US week 3 and 4 in the coming days.

wk3_wk4_20131105_NAsfcT

Here’s that trend towards negative. Check out the AO which goes from a very strong positive.

nao_sprd2

ao_sprd2

I believe we see warming behind this week’s cold but another cold blast comes down by the end of the month. We shall wait and see.

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