As of this morning, December 22, just 26 percent of the U.S. has snow cover (compared to an average of around 38 percent). That’s the smallest portion for the date in a decade. There hasn’t been less since 2004, when a mere 18.5 percent of the nation was covered in snow.
It’s been an amazing reversal in snow fortunes for the Lower 48. On November 17, 50 percent of the Lower 48 was covered in snow, the most in 12 years of records (by a long shot).
Yes, a big storm will charge from the South into the Great Lakes Christmas Eve, but temperatures are so mild relative to normal that only a few areas will gain snow cover. (A second storm will replenish existing snow cover in the intermountain West).
The map below provides a sense of the locations most likely to gain snow cover between today and Christmas morning – most areas expected to get new snow already have snow on the ground:
Some areas – especially in New England – may lose some or all of their existing snow cover due to much above normal temperatures and rain. Look at the Christmas Eve temperature forecast difference from “normal” below: the red and burnt red areas along the East Coast are 10-25 degrees warmer than average:
The GFS model offers this forecast (below) of snow cover Christmas morning across the Lower 48:
In the above map, I outline in blue areas most likely to have a White Christmas. I ignore the areas shaded in light gray – as they portray amounts of less than an inch and may well cover locations where air temperatures will be too warm for any snow to accumulate. Furthermore, the official criteria for a “white” Christmas is 1 inch of snow on the ground. Also, the stripe of blue signifying snow around Chicago into southern Illinois is suspect as temperatures in this region may well be too warm for any snow that falls Chistmas Eve to accumulate.
Compare the above to the map below which shows historical odds of a White Christmas. Many areas that usually have at least 50-50 odds of snow the ground will not this year, especially in the Northeast, southern Great Lakes, and northern Ohio Valley.
The cold air required for more snow across the nation may not remain bottled up for long. There are indications it may start to spill into the U.S. in the days prior to the New Year.