Heat is made worse by humidity, and cold is made worse by wind. As we begin the work week, the wind is going to be the big factor in our weather.
The Boston area finally received its first snowfall over an inch with isolated areas reaching more than 5 inches. The storm, which brought the area’s first significant snow, will now move to eastern Canada and grow into a very intense storm. This will be too far away to bring us clouds and precipitation, but because the pressure will be so low in that storm, air must rush in from all directions to replace it. As this happens, we will need to get used to the wind.
What you’ll notice from Monday afternoon through much of Wednesday will be a cold, northwest flow of air. On a weather map, isobars are lines of equal pressure. The closer together these lines, the more wind. It’s the same principle of a topographical map: the closer those lines, the steeper the climb.
The cold isn’t unusual
While temperatures are below average the next few days, they will still be well within a typical range for the third week of January. As a matter of fact, this week is the seasonal normal for our coldest week of the year. I can’t possibly know exactly how much more arctic air is destined for the region, but it wouldn’t be out of the realm of possibility that this week is one of the top two coldest of the entire winter. Last year, of course, was an anomaly as February was the coldest month.
The second half of the week features seasonably cold air, less wind and plenty of sunshine. It will feel quite comfortable after two to three days of wind and cold.
I’ve already seen all sorts of predications for the weekend storm. It’s not prudent or accurate to start throwing out accumulation totals on a five-day forecast. The atmosphere is a fluid, and if you watch the loop below of the water vapor moving across North America, you can really see what I mean. Because fluids move in reasonably predictable ways, computer models are able to forecast what’s going to happen in the future.
However, there are limitations in this forecast and slight changes Tuesday and Wednesday can have large impacts on the weekend storm. Nearly all the models agree: there’s going to be a coastal storm and even the different versions of the same model, the ensembles, see a large coastal storm around Saturday.
Odds favor at least some snow
At this point in the week, I’m comfortable talking about odds. The odds are probably 60 percent that southern New England will see accumulating snow this weekend. That also still leaves a 40 percent chance we won’t. The odds are closer to 90 percent that a storm will develop in the first place, which is why you are likely hearing about it already.
Here’s what I would do to get ready for a possible storm five days away: Check the snow blower, and make back-up plans if you had to travel this weekend either by air or car. You could move a flight at this point from the weekend, knowing the move might be completely unnecessary. I’ll be updating the forecast here and on Twitter @growingwisdom in the coming days.