Christmas 2017 is drawing near and at this time of the year (aside from when we are dealing with snow storms like last night) I am often asked about the chances for a White Christmas. Today is December 14 and Christmas is 11 days away. Which means we are outside of the range where confidence in a forecast is typically high. Particularly in the winter season, and particularly in a challenging climate such as the one we have in northeast Ohio and western PA, I am rarely confident in a forecast beyond 5-7 days.
Looking at a national weather app or web site for a specific Christmas Day forecast this far out?
What we CAN do is look at the overall pattern is likely to be across the country and talk about what the possibilities may be in said pattern.
There is decent model agreement in the overall pattern across the lower 48 states at Christmas: a dip in the jet stream over the Southwest, a ridge of high pressure off the coast of the Southeast and cold air residing near the US-Canadian border and probably in much of the Plains and Rockies as well. The pattern in the upper levels of the atmosphere:
Note how I have “stormy zone” on these maps. There is likely to be a strong temperature “gradient” in place over the country (quite balmy in the Southeast and cold from the Plains west and also in southern Canada). Storms like to reside in between warm and cold air masses. With this type of a setup, it’s likely to be unsettled from the Southwest through the Plains and into the Midwest. This far east? Tougher call. This type of a configuration sometime produces ice storms and mixed precipitation events around the Midwest and Great Lakes.
So I would sum up my thoughts like this:
It will not be super cold here. Very unlikely to be as cold as it is now.
It will not be a bone-dry, sunny period at and around Christmas. Odds favor bouts of precipitation.
What types of precipitation. Timing of any storms. How much snow will be on the ground, if any. In other words, specifics.
Notice we have not picked up an inch or more of snow on December 25th since 2003.
We’ll really be able to start honing in on the Christmas forecast early next week.