Weather! Final look at this weekend’s snow

I want to wish all of you a happy holidays and safe travels this season. Thank you all for your support this year, and I hope you’re all able to spend a happy and safe holiday (or holidays) with your loved ones. Perhaps I shouldn’t have gone to the barber this week – my hair […]

December 25, 2010; 1:59 AM • by Weather Dan

I want to wish all of you a happy holidays and safe travels this season. Thank you all for your support this year, and I hope you’re all able to spend a happy and safe holiday (or holidays) with your loved ones.

Perhaps I shouldn’t have gone to the barber this week – my hair is easier to pull out when it’s long. In fact, it’s really tempting to just throw my hands up in the air and say “tell me how much you got when it’s all over,” but I can’t do that. This week has shown me models that zig when they usually zag, flip when they usually flop, and come up with completely original catchphrases when they’re only known for cliches. I have no doubt it will be much fun to talk about and reminisce after the event is over, but right now, all I want to do is bang my head repeatedly against the wall. To make matters worse, today we’ve had one entire model run of the NAM and GFS discarded (and parts of two others made highly questionable as a result) by the Hydrometeorological Prediction Center because it contained bad initialization data.

As I’ve said all week, this weekend is a tricky forecast. There are two areas of low pressure, one riding the northern branch of the jet stream across the northern Plains, and the other is currently located over west-central Texas, carried along by the southern branch. Over the next 48 hours, these two systems are going to merge together, or phase, providing enough energy for a strong low to develop off the east coast. I’ve discussed some detail already the perils of coastal lows and how much track can influence snowfall totals in eastern Virginia, but here again is the caveat: a change in the track of this storm by 50-100 miles can significantly alter snowfall totals.

It bears repeating: a shift in the track of this low WILL change snowfall amounts, likely for the higher.

Saturday: Temperatures Saturday will likely get into the upper 30s before dropping as the developing low approaches. Some moisture aloft may overrun the cold air already in place and produce some snow showers into the overnight. Depending on exactly how much moisture gets into the area, it could be as much as an inch before midnight, though I think this is the high end of the envelope. I think it’s more likely that Richmond will see anywhere between a dusting and half an inch before midnight. Overnight lows will be in the upper 20s.

Sunday: Snow will continue through the overnight hours, with the heaviest snow coming later Sunday morning, if it happens at all. This is, by far, the part of the forecast that I have the least confidence in. Prior to today, I would have said that Richmond might see an additional dusting to up to two inches (for a three-inch storm total). Based on what I’ve seen tonight in the model data and from other meteorologists, and taking into account effects like the moisture needed for atmospheric saturation…I’d say we’re looking at more like 3-6” from this system total.

Areas closer to the coast – especially Hampton Roads – will see even higher accumulations. 5-9” isn’t out of the question there. The northeast corridor and New England are looking at the possibility of a foot of snow along most of the I-95 corridor.

Now’s probably a good time to mention that “along the I-95 corridor in New England” is exactly where I am at the moment.

If this storm tracks closer to the coast – and there’s been some hinting from the models that it might – these totals could go even higher. I’m guessing we’ll see the first watches or advisories go up in the morning.

Remember those backup plans I strongly hinted at earlier this week? Now’s the time to decide whether or not to put them into action.

Again, wishing a very merry Christmas and safe and happy holidays – free of bizarre snow-related incidents – to you all.

December 25, 2010 1:59 AM 2