1/26/2011: Something to Talk About at 11:30 PM

Looks like overall onset has been pushed back a few hours, enough for it to be considered that whatever happens will happen on Wednesday. Not so much on Tuesday.

Local mets are generally calling for either all rain or a snow to rain solution. This is, in the general parlance, what we like to call "wrong". If rain and snow are involved, it'll be the other way around. I'm backing off from my pessimistic all-rain solution for several reasons.

First, it looks like we've reached the northern extent of how this thing can track. Second, as more complete information is fed into the models, it appears development occurs a little earlier. Earlier development means a stronger system by the time it gets up here. With the counterclockwise rotation of a low pressure system, that means the cold air gets drawn in from the north at the same time that warm moisture gets drawn in from the south. And since we're on the northwestern side of this thing, cold air is going to trump the warm, at least for the parts that matter.

So, I'm not saying it's not going to rain. It's likely going to rain in the immediate metro area. The further north and west you get, the less chance there will be of rain, but less precip too. The models, in general, have been lining up some support for this as well.

The overall timeline is something like this. Wednesday morning to early afternoon, some light rain starts. Temperatures above freezing both aloft and likely below as well. Wednesday late afternoon to evening, some heavier precipitation starts, temperatures drop. There will likely be an extended period where snow falls but does not stick to the streets because surface temperatures will remain above freezing until the onslaught of precip cools it down enough. Wednesday night until the early morning hours Thursday, perhaps around dawn, snow, possibly heavy at times.

Several interesting things to take note of. First, this is going to be the really heavy, wet snow. Nothing fluffy. Ideal for sledding and snowballs. Very hard to plow, especially larger quantities. Second, while snowfall ratios are typically 10:1 (inches of snow:inches of liquid), this is probably going to be closer to an 8:1 type scenario. Like I said, wet and heavy. It's basically going to be slush falling from the sky.

Total amounts? Glad you asked. There's still a shot the Valley makes out from this one as it's going to be mostly snow there, but with the evolution in track they're getting less in the way of liquid. Models that just came out have been favoring a 4-8 or 6-10 type solution for the DC area (and that's with about 6-9 hours of light rain to start). I choose to not be so bold just yet. We're still about 36-48 hours from onset of snow, and this is the type of storm where very small changes mean very large differences.

Generally speaking, for the Valley I'm favoring a 3-5 inch type system, immediate metro area (where there will be rain issues) I'm leaning towards a 2-4 incher. Bullseye is likely a little to the east and north of Baltimore (again). Think Philly? Aw hell, I was going to try avoiding it but I might as well do the probabilities for DC at the least.

DC:
Nothing: can't rule it out. 15%
0-2 inches: 25%
2-4 inches: 35%
4-8 inches: 15%
8+ inches: 10%

You can tell that I'm still very guarded with these estimations. Despite the pretty decent model consensus, this winter has just been impossible to nail down properly. I like what I've seen today in that most every model that's come out over the past twelve hours has shown decent stuff for DC. But it's also kind of hard to fathom a significant snowstorm 24 hours after highs in the upper 40s.

I, as ever, continue to reserve the right to be wrong.