Mar 29, 2012; 10:41 AM ET
Thursday, 11:55 a.m.
We're off the warmest of the warm, though there's still plenty of warmth to go around, that's for sure. Any time a storm goes by, or a front approaches, and you mix in some sunshine and a gusty wind, the air can easily become very well mixed. When that happens, temperatures can jump through the roof. That said, there has already been one attack of cold this past weekend, and another is following through the Great Lakes into the Northeast today and tonight. This time, it may be cold enough long enough for it to snow and stick in some places late tomorrow and tomorrow night, believe it or not. More on that in a bit.
To illustrate how easily it is to warm on a dime, take my back yard yesterday. Ahead of a developing line of thunderstorms, there were places above the inversion and places below it in central Pennsylvania. Those above it wasted no time putting a southwest to west wind to go use. Altoona jumped quickly to 60 by 9 a.m., and by 11 a.m. ahead of the thunderstorms, it had reached 71. Meanwhile, it the true 'pits' of central Pennsylvania, like State College over to Lamar, Lock Haven and Williamsport, it was stuck in the 40s with little wind and not much more sun getting through right in front of the thunderstorms.
I have a standing ride with a friend at lunchtime on Wednesdays, and it was touch and go as to whether or not we'd do it given the thunderstorms, but they cleared before we were to meet, so I said "let's do it." Well, I was prepared for 65- to 70-degree warmth, not 48 degrees with a breeze and sopping wet roads! My four-mile ride to campus pretty much numbed my legs, and I was about to give up, since I had no shorts. But as I waited for my friend to show, the sun began to pop through the clouds, the wind rose, and you could literally feel the temperature rising. By the time we were 30 minutes into our ride and readying to make a steep climb, we were shedding most of our extra layers, as the temperature had risen from 48 with overcast, grey skies, soggy roads and little wind to 70 under partly sunny skies with a howling west wind and rapidly drying roads! I have never witnessed that dramatic of a temperature rise in such a short period of time in all my days!
It just goes to show you how easily it can warm with a little wind and sunshine. That's been happening on a nearly daily basis from the Ohio Valley to the eastern Rockies. Any time the last vestiges of any hint of arctic air are gone, just start looking at the highest numbers and go with or above them. I posted a couple of weeks ago on the simple math of it all. Take the projected 850mb temperature in degrees Celsius, add about 15 degrees to it for anything near sea level, and that will give you a good approximation of the potential high for the day, assuming at least partial sunshine and any kind of a wind.
By contrast, it has actually snowed the past couple of days in portions of northern New England. The Green and White mountains have picked up the bulk of the snow, on into the Longfellow mountains in Maine. The air coming across the northern and eastern Great Lakes into the northern mid-Atlantic states and New England on the back side of this upper-level trough isn't exactly cold, but it will be attacked later tomorrow by a disturbance coming out of the Midwest, seen here on the 12z NAM for tomorrow morning:
This will send a low pressure area scooting across the Midwest and the Ohio Valley late tonight and tomorrow, then off the mid-Atlantic coast Saturday morning:
The air north of the track of the storm won't be bitter, but it will be cold, and cold enough to support snow. So, areas from Buffalo to the Endless Mountains and the Poconos are at risk of seeing wet snow spreading quickly from west to east late tomorrow and tomorrow night before it ends. If the precipitation is strong enough a little farther north, a few inches could accumulate across the Finger Lakes over to the Adirondacks and the Northwest Hills of Connecticut, believe it or not!
This is not without precedent. Just two years ago on May 11, 2010, snow fell in portions of Pennsylvania, so it can happen at the end of March and the beginning of April!
It should also be pointed out that this storm will also have a warm side to it. Much like the system that streaked across the Great Lakes into the Northeast yesterday, there will be a surge of warm air on the south side of the storm. It won't get as far north as the warm surge yesterday did though. Nevertheless, you may go from places with clouds and temperatures in the low and mid-40s Saturday to some sun and highs in the mid- to upper 70s in central Virginia!
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