Merry Christmas! The best numerical weather prediction models in the world have been churning out 5-day forecasts for the past few days that will make someone pull their hair out. The main question is how far east will the major extratropical cyclone or blizzard develop over the Atlantic off of New England. The track details will determine who will get a dusting of snow and who could possibly get 1-2 feet. As the event unfolds, this post will provide additional links.
Current precipitation totals from the NAM 00z model for December 25, 2010 for liquid is well over an inch over most of Southern New England. A 1o to 1 ratio for snow to rain along with blizzard winds will make early week travel as bad as at Heathrow, where snow can be a “very rare and exciting event”.
From meteorologist Ray Hawthorne, fellow FSU grad:
This is one of the most complex forecasts I’ve seen since the infamous, so-called Blizzard of 2000. There appear to be four distinct shortwaves — one along the Texas Gulf coast, another in the Middle/Upper Mississippi Valley, a third in the Middle Missouri Valley, and a fourth in western Ontario province, Canada. The numerical models are having an extremely difficult time handling the interaction of these four waves. Even worse, the model initial conditions earlier today were not very good (see NCEP model diagnostic discussion). Add in the Gulf Stream and what is a gradual breakdown of the high-latitude blocking we’ve seen for several weeks and you’ve got chaos. That said, the trend is clearly westward in the last several NAM and GFS model runs — something that is going to be extraordinarily hard to ignore for much longer. The upcoming two model cycles of the ECMWF will be extremely significant because watches and warnings are going to be needed for many areas in the Mid Atlantic and Northeast fairly quickly. This is the lowest confidence forecast that I can remember seeing in this past decade.