This winter was never expected to be great as a result of the La Nina conditions in the Pacific, but what wasn’t expected has been the persistent -NAO. In the negative phase, the North Atlantic Oscillation can bring a blocking high pressure area over Greenland which allows cold Canadian air to settle over the eastern US while the storm track is forced south and (hopefully) up the eastern seaboard. Most of our major snowstorms have happened during times of the negative phase of the NAO. Of course, in the mid-Atlantic snow is rarely easy, so the -NAO is not the only thing we need, but it helps. Unfortunately, in spite of the -NAO, there hasn’t been any true arctic air intrusions on our side of the globe this year, so even with a good index, snow has been scarce. Many winter forecasts that I read back in October and November spoke of the possibility of the second half of winter being better around these parts as the long range models were already showing the blocking pattern emerging, and there was some hope that the Pacific would be more cooperative by February. I’m not sure if that is what is happening, but regardless, we do have a couple of systems to track, with one of them potentially being a major event.
First on tap is late Monday and Monday night. A system will approach the area from the west and it looks like the boundary between frozen and not-frozen precipitation will be setting up across central MD. Depending on where you live, you can probably find a model du jour showing what you want at your location. If you want snow, the Euro is showing most areas north of about route 50 getting 1-3″, while the GFS shows mostly sleet and freezing rain for most of us with snow being limited to the Mason Dixon line. The NAM brothers start as a mix, then snow when the column cools, and then back to light blah. Then there is the Canadian and UK models…
Making a total guess right now, I think most of us will see some snow as the precipitation starts Monday evening, and then it will change to something else much like the December storm, but without the really heavy snow to start. Maybe a couple of inches in the favored areas before the changeover, and hopefully it won’t bring much freezing rain. I’ll certainly update as things become more clear.
The second system for Thursday is worth keeping an eye on. The GFS and Canadian (CMC) both favor a decent storm just off the coast, but there are some issues with cold air with the GFS (well, at least the current GFS. There is a new version of the GFS that is scheduled to replace the current one in February. That the new one is available for public viewing and it likes snow for Thursday. Like I said, if you look at enough weather models, you’ll almost certainly find the weather that you want). The Euro hadn’t been showing much for Thursday, but today’s midday run took a decent step in the right direction, so I think this one could be the best chance we have had in a few years for an area-wide warning event. Hopefully I’m not jinxing it.
The Weather Mill 