Monday, November 10, 2014

Relentless November Arctic Cold In Plains, Midwest, Rockies to Last Into Next Week

A potent blast of Arctic air is plunging into the nation's mid-section and south this week, sending temperatures crashing to values you might expect in mid-winter. And it's going to last for awhile!

Highs much of this week should hold in the teens or 20s in the northern Rockies, northern Plains and Upper Midwest. Some snow-covered areas of the northern Rockies and northern High Plains may struggle to rise out of the single digits. 

Subzero cold is expected to be most widespread in the fresh, snow-covered areas of the northern Rockies and northern High Plains. Later in the week, some of the areas that received heavy snow from Winter Storm Astro may also dip below zero, including, possibly, the Twin Cities metro area.

While there will be some daily record lows threatened over the next several days, what will stand out about this cold snap is its longevity.
Above is a European model forecast loop through the middle of next week depicting where the coldest air will be.
With blocking high pressure aloft over eastern Alaska and northwest Canada, a direct pipeline of cold air will come from Siberia to near the North Pole, then southward into Canada and the U.S., particularly the Plains and Midwest into next week. 
This is a classic Arctic outbreak pattern that will remain largely locked in over these areas for the next 10 days, at least.
For example, forecast highs in the Twin Cities may actually be colder next week, and will be below freezing. This will rival the longest November subfreezing streaks on record, there (see graphic at right). Many of those days will see daytime highs colder than their climatologically coldest average highs in January (23 degrees).
After highs topped out near 80 degrees in Dallas Monday, highs into next week will do no better than the 50s. In fact, some days may not see highs get out of the 40s, there. For reference, average highs in Dallas during the coldest time of year (late Dec. into early Jan.) are in the mid-50s.
Oklahoma City may not see the 50-degree mark until late next week, at the earliest, after soaring into the upper 70s Monday. Their average high in early January is 49 degrees.
There are also indications in our medium-range guidance that the cold will also encompass more of the Northeast and Mid-Atlantic states next week. For instance, highs in Washington, D.C. may hold in the 30s or low 40s next week.
Given this cold air in place, we will keep a close eye on any jet stream disturbance rippling through. Each has the potential to produce snow, sleet or freezing rain. 

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