Plain-language summary:
After being very cold through Monday, it will turn milder, yet for most, the transition period will fail to produce much snow like such periods often do. Instead, it will be mostly dry through Thursday except a little snow from southern Vermont to southern Maine Tuesday night into Wednesday. Shallow cold air will lead to one last chance of wintry precipitation Thursday night into Friday, though it is more likely to be freezing rain than snow. It then turns warm through following week with frequent rain chances, though any day that does turn sunny could be exceptionally warm for March. Northern areas may still have the risk for wintry mix or freezing rain depending on the exact configuration of the weather pattern. It will likely turn stormier and than colder for mid-March, possibly with snow returning.
Meteorological discussion:
Very cold Arctic air through Monday, then milder with light snow in southern Vermont to southern Maine Tuesday night into Wednesday while it stays dry to the north
After a brief thaw yesterday, a very cold Arctic air mass directly from the north with no modification will likely bring the last sub-0F (-18C) night of the winter tonight as surface high-pressure crests overhead leading to an ideal radiational cooling setup of light wind, clear sky, dry air, and deep snow cover. Afterward, the arctic surface high-pressure will move offshore the U.S. East Coast, and a series of elongated clippers will pass to the north next week. Both of these combined will lead to a warming southwesterly flow aided by a stronger March sun. An almost closed-off upper-level low will enter the western U.S. on Monday, with weak pieces running out ahead of the main upper-level low that will produce light warm advection snow in southern Vermont to southern Maine later Tuesday into Tuesday night. This southern jet disturbance has a decent amount of moisture, and if the prevailing jet pattern had been more amplified, especially with the polar jet upper-level trough being stronger and phasing with and picking up the southern jet disturbance, this could have been a much bigger snowstorm like models had shown a few days ago. However, this will be yet another potential bigger storm that mostly fails to materialize. The northern upper-level trough is very flat and is not digging far enough south nor in the right position to pick up the juicier southern disturbance, leading to a very stretched out and suppressed disturbance with relatively weak forcing and precipitation at any one location yet again. Central Maine could get the jackpot with locally up to 4" (10 cm). Areas from the U.S./Canada border on northwestward will stay dry in between the clipper passing to the north and the stretched out southern disturbance to the south Tuesday night into Wednesday, though everyone will turn milder and see increasing clouds.
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| Source: TropicalTidbits |
Transition period to warmer weather mostly fails to produce wintry precipitation except one last iffy chance Thursday night into Friday
Afterward, the weather pattern will change dramatically, powered by a much stronger Pacific jet (+EPO), +NAO, +AO, and -PNA. This change will not only scour the arctic air from the contiguous U.S., but also force upper-level troughing in western North America that further promotes a ridge in eastern North America and western Atlantic and a storm track way to the north. It is ironic that we had so much potential for storminess and snowiness from a temperature battleground over the past month, yet the weather pattern ended up being repeatedly too suppressive, and now, it will simply flip 180 degrees to having way too strong of a ridge for snow in our region, especially in southern areas, after next Friday. It has been an incredible waste of potential for big snowstorms; it just needed to be in between the suppressive and ridge-dominated patterns. Even the transition period from cold to warm pattern, which usually produces a decent snowfall, appears to mostly fail to produce much if any snow for most.
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| Source: Climate Prediction Center |
However, there is still one last slight chance for snow for northern and eastern parts of the region next Friday. On Thursday, an arctic surface high-pressure will press southward just slightly, barely penetrating south of the U.S./Canada border, behind a stalling cold front from the previous weakening clipper passing to our north on Wednesday. Meanwhile, the main upper-level low, though weakening, will finally push northeastward into our region as another upper-level trough into the western U.S., pumping the eastern U.S. ridge and leading to southwesterly flow aloft. This flow of warm, moist air from the Gulf of Mexico will ram into the shallow arctic air in northern and eastern parts of our region, leading to possibly heavy precipitation Thursday night into Friday. Most models indicate that the arctic air, although is very cold, will mostly stay just north of our region and is so tenuous and shallow with above freezing temperatures persisting aloft for most of the region except Maine, where cold air damming will help block the surge of warmer air. But if the cold air can press in more, and the upper-level low is timed perfectly to arrive just as the cold air is coming in (not too early, before the cold moves in, and not too late, after the cold is about to leave), it could be just cold enough for a more widespread wet snow. Most likely, the cold air will be shallow and dammed against the Appalachians and channeled southwestward through the St. Lawrence Valley, leading to freezing rain, and icing could be substantial for some given the strength of the shallow arctic air. The system could also be weaker, resulting in little precipitation, especially if more of the energy gets pulled out Tuesday night into Wednesday ahead of the main upper-level low.
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| Source: TropicalTidbits |
Warm next weekend through following week with frequent rain chances, maybe still wintry precipitation chances in northern areas
Despite the low-level arctic air that will be initially difficult to scour out, eventually, the next upper-level trough will promote a storm track well to our north next weekend, leading to the arctic air retreating well to the north, warming temperatures, and some rain. A blowtorch for most of our region is likely at some point between next weekend and the following week given the strength of the upper-level ridge, with several storms tracking well to our north and warm southerly flow blasting into our region. Temperatures could exceed 70F (21C) in lower elevations if there is enough sunshine! Occasional cool downs behind storms could occur, but the air masses will not be very cold. Even the feedbacks of frozen Great Lakes and deep snow cover will be no match for the strength of this ridge, and the warmth will obliterate the snowpack. Even if the ridge is weaker than modeled like has been the case for the past month, it will likely not be enough to change this general narrative. Unless it turns very cold again in mid-late March, it will be the 6th warmer than average March in a row. Given the warm, moist Gulf of Mexico air involved, there could be heavy rain at times depending on the storm track, especially along cold warm fronts, but the storm track could be so far north that the best dynamics and heaviest rain stays to our northwest, especially next weekend. Still, it will likely not be a "clean" warm-up with dry weather and sunshine, perhaps except next Sunday and following Monday, which is rare this early in the spring anyway, especially in northern areas. Such warm air masses traversing over snow cover and cold ground usually lead to a lot of low clouds and fog especially initially with the warm advection, and this could be amplified with the progression of storms and repeated fronts. If the overall upper-level trough/ridge pattern in western/eastern North America is a little weaker, there could be sneaky surface arctic high-pressure systems well to the north that lead to much cooler surface temperatures, especially in northern areas, while it stays warm aloft, a recipe for low clouds and even a wintry mix or freezing rain if the storm track is close enough.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
Cold air likely to return at end of following week, possibly with storminess and even return of snow
Models are also in good agreement that the upper-level ridge will gradually weaken towards the end of the following week, and with the Pacific jet weakening, arctic air is likely to make a comeback across southern Canada and northern U.S., initially to our west but eventually spreading eastward for mid-March. In the transition period, it could be quite stormy, with warmth and heavy rain and possibly even thunderstorms. But it is possible that as the cold air and baroclinic zone slowly pushes southeastward that there is one or two storms that spin up along it in which our region is on the cold side, leading to snow. It is almost always difficult to get a big snowstorm from rain changing to snow, as usually the cold air needs to be established first, but in such an amplified weather pattern, it is plausible even if not very likely. It will be mid-March with an obliteration of the snowpack, so any cold air will not be nearly as strong as we have seen over the past month, but it could still be cold enough for snowfall, and if the weather pattern is less suppressive as it usually is later in March as the jet stream climatologically moves northward, and it becomes easier to tap into the strengthening warm, moist air masses in the southern U.S., the potential for bigger storms still exists. Of course, with averages rapidly climbing, it will be more difficult to keep precipitation as snow, but it is certainly still possible through early April.
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| Source: TropicalTidbits |
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