Despite an upcoming cold weekend, our recent warm weather pattern will re-emerge next week and it’ll likely continue right past Christmas Day. The month of December so far has been well above normal in the Mid-Atlantic region (+10.8 at PHL, +8.1 at DCA, +11.2 at Central Park) and there will be a setback this weekend, but the eastern US will warm up significantly next week while the western states cool down dramatically. In fact, record warmth is likely in many areas east of the Mississippi River by the middle of next week.
A major cold shot will arrive by the weekend in the Great Lakes, Northeast and Mid-Atlantic regions, but it will be a “come and go” event lasting about three days only. Temperatures on Saturday, for example, may struggle to reach the 40 degree mark in the I-95 corridor and overnight lows this weekend could visit the 20’s in many big city suburban locations. This cold shot is also likely to result in the first serious “lake effect” type snows for those areas just downstream from the Great Lakes given the big difference between the expected cold air and the still relatively warm lake water temperatures.
Next week’s major warm up
Once the high pressure system associated with this cold air outbreak pushes off the east coast, widespread warming will occur next week in the eastern half of the nation. In fact, by the middle of next week, record warmth could once again be the main weather news in much of the eastern US while the western states remain quite cold. The overall warm weather pattern is very likely to remain in place in the eastern states late next week - including on Christmas Day - and into the following week with more record warmth possible.
Many El Nino winters start off on the warm side in the eastern US and then get colder as the winter season progresses. As a result, our 2015-2016 Winter Outlook (http://www.vencoreweather.com/2015-2016-winter-outlook) emphasized a “backloaded” winter with a warm start and then progressively colder relative-to-normal as the winter season progresses with the bulk of the snowfall occurring during the second half of the season. So far, the warm start has certainly fallen into place and it should start to cool down as we move into January and beyond. Indeed, there are the beginning signs for an upcoming “stratospheric warming” event over the next couple of weeks and ultimately this could have an influence on the overall temperature pattern in the eastern US.
Meteorologist Paul Dorian