This morning on Twitter someone asked me about a white Christmas.  In Portland the chances of a white Christmas on any given year are slightly better than flipping a coin. Although Bing Crosby loved to sing about them, most of the lower 48 states are typically green not white at Christmas.  Back in 2009 about 60 percent of the country, excluding Alaska and Hawaii had a white Christmas.  That was the greatest snow cover on Christmas day in the past 13 years.

Christmas morning 2009 saw a majority of the northeast with snow cover.

A white Christmas is defined by the National Weather Service as having one inch or more of snow on the ground when the observation is taken Christmas morning, usually around 7 a.m. eastern standard time.  If we had a foot of snow Christmas night, it’s still not a white Christmas.

In Maine, back in 2009 there was a wide range of snow on the ground from the coast to the mountains, but last year the usual warmth prevented all but northern Maine from a white Christmas.

Here in New England the climate sites with the greatest chance of a white Christmas are Caribou and Houlton.  There you have nearly a 90 percent chance of at least an inch of snow on the ground.  Indeed even last year when temperatures where in the 60s Christmas day, Caribou still had 3 inches of snow on the ground. Boston in contrast has only had a white Christmas 8 years since 1872.

The map below shows where to make your reservations for Christmas morning if you want to ensure it’s white.  You could also hike up Mount Washington, there’s sure to be snow their Christmas morning.

The northern tier of the United States typically has snow cover at Christmas as does the mountains.

The computer models we use actually predict snow cover. This is based on what will fall and what will melt.  The map below shows how much snow is forecast to be on the ground the Friday before Christmas December 23^rd.  Since right now I don’t see any snow storms after that, I am predicting bare ground along the immediate coast including Portland at Christmas with increasing chances of a white Christmas in areas west of the Turnpike and north of Portland.

Warmer air before Christmas morning will likely bring back the grass along the coast.

Temperatures last year reached into the 60s for Christmas Day.  This year it looks unseasonably warm for Christmas, but no record warmth and certainly no 60s.  It will be a race to see if the warm air just before Christmas melts the snow along the coast or not.

I will be updating the forecast on Twitter @growingwisdom please follow me there.