Arctic Outbreak to Grip the Region

Posted: January 18, 2013, 12:51 pm by ntroiano

It’s time to dig out those heavy coats, scarves, hats and long johns…as frigid temperatures are expected to return by the middle of next week. We’re not just talking about your typical run-of-the-mill cold either. Bitterly cold arctic air is expected to spill into the Northern Plains later this weekend and subsequently steam-roll into the Midwest, Northeast and New England by the start of next week. Temperatures across a good portion of these locations will be the coldest they’ve been since January 2009 – which is just about four full years ago. So, what exactly is responsible for this rare arctic outbreak and how long will these cold conditions last? If you want answers, then you’ve come to the right place!

As mentioned during last week’s blog, a recent “sudden stratospheric warming” about 60,000 – 80,000 feet above the surface is expected to trigger a much colder airmass to move across an exceptionally large portion of the Eastern US by early next week. Temperature anomalies associated with this event are then expected to propagate through the mid-troposphere (as seen in the attached image) and induce cooling near the surface. Although these events don’t always translate to cold weather outbreaks, the model guidance has been consistent in showing this situation coming to fruition. Interestingly enough, the January 2009 arctic outbreak can also be attributed to a “sudden stratospheric warming,” which gives us growing confidence that the upcoming situation will be every bit as powerful as advertised.

The heart of the coldest conditions will be felt across the nation Tuesday into Wednesday of next week. During this time, low temperatures will drop below –20°F across parts of the Northern Plains and interior New England…and with not much warming expected during the day, highs should remain below zero. Although the heart of the bitterly cold conditions will bypass the heart of the I-95 corridor, high temperatures will likely not make it out of the 20’s for cities such as Philadelphia, New York and Boston. Lows in these same spots will likely dip down into the low teens…which is 10 – 15 degrees below normal. Even across the Deep South, readings are expected to dip well below freezing across parts of Louisiana, Mississippi, Alabama and Georgia. Even Northern Florida is expected to get in on the action, with lows dropping into the 30’s by Wednesday morning. Frost and freeze advisories and warnings will likely be needed, as most of these places have not seen an air-mass in the 20’s and 30’s since last year.

So, will this cold weather last into February and when is our next shot at some significant snow? Although the heart of this arctic airmass is expected to exit the region by the end of next week, temperatures are expected to average out colder than normal into the first half of February. The main mechanism behind this will be the evolution of the Madden-Julian Oscillation (MJO). During the upcoming period, the MJO is expected to enter phases 8 & 1…which is associated with colder than normal departures across much of the central and eastern part of the nation (see attached image). Cold air is also likely to be reinvigorated on or around the 10th, when the third and final arctic push from this most recent stratospheric warming is expected to traverse the region.

In terms of snowfall, the main types of systems associated with these cold air outbreaks tend to be fast-moving clippers, with low-end snow amounts probable for the northern-tier of the nation. The most likely chances to see a more significant system…such as a coastal storm…would be during brief pattern relaxations. The most favorable times for these would be between January 26th and 30th and again from February 5th through the 9th. Undoubtedly these dates will be refined somewhat as we finish out the month…so make sure to check back for more updates!

Interested in a more in-depth analysis for future weather events in your area? Contact Kevin Hopler (kevinhopler@weatherworksinc.com) for more information about our suite of Long-Range and Winter Risk products.

Lead Long Range Meteorologist
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