We learned how ineffective staring at long-range computer models can be when trying to pinpoint a forecast for many days in advance when we followed the GFS model forecast for Thanksgiving for a full two weeks (Thanksgiving Leftovers), so let’s look at a potential Christmas snowstorm in another way–from a current satellite image.
Snowstorm Potential
While the computer models have been wildly erratic with the placement of a storm for the central and eastern parts of the United States for December 24 through December 25, they’ve been extremely consistent that there will be a major storm. Erik at MemphisWeather.Net talked about the possibilities of the Christmas storm for the south in a recent post–White Christmas Update–6 days until…snow?.
(This is more than we can say about the computer models for the monster snowstorm along the Eastern Seaboard this weekend–something being talked about by friends Wx-Talk, PhillyWeather.net, and Maryland Weather, to name a few. The models were not consistent with even the strength of that storm.)
Hawaii Connection to Upcoming Storm
One of the things that I’ve talked about recently as a possibility of widespread White Christmas (Conditions Ripe for a White Christmas) is an active southern branch of the jet stream, and a storm in the southern branch of the jet stream will become part of the big storm around Christmas. The following image shows the storm (at about 145 west if you can read the grid):
Complicated Path
The storm system will not simply move from west to east across the Pacific and across the United States; it will move northward and weaken and before moving through the Pacific Northwest late in the weekend. The storm will lose most of its identity (but its energy and moisture will survive) and then merge with additional storm systems and strengthen into a stronger storm by the time it emerges from the Rockies.
With a path like that, it should not be surprising that a simple computer model isn’t having a difficult time forecasting its track, but there will be a big storm from December 24 through December 25–the question is simply where.
–Paul Yeager
