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The following is provided by DC Severe Winter Weather:
Where’s the Snow?
As you all probably remember, we called for a winter with average to above average snow, but most of the area hasn’t even seen a single flake. Despite this slow start, we stand by our earlier prediction for 100-150% of normal snowfall.
What’s going on?
The current pattern is extremely unfavorable for snow, and is not expected to change anytime soon. Take a look at the GEFS ensemble mean for Christmas:
Red denotes areas of higher geopotential heights, corresponding to warmer air. Blue denotes areas of lower geopotential heights, corresponding to colder air. (The map is centered over the north pole and shows the entire northern hemisphere, so it might be a little disorienting at first)As you can see in the image, a dome of warm air has built up over the eastern US, deflecting snow and cold air to the North, while colder air dominates in the polar regions and west coast. All of the teleconnections: (AO, NAO, EPO, PNA) are unfavorable for snow in DC. To get snow in DC, you’d want to see the opposite of this map: reds over the North Pole and Greenland with blues in the eastern US.
Look for this pattern to begin to shift as we move into January into one more favorable for snow in DC. For now though, we don’t see any possibility of accumulating snow through at least Late December.
We’ll continue to update you as the winter goes on and our thinking evolves!
