Cold but mostly dry weekend; light snow in southern areas early Sunday and late Monday; gradual warmup next week with snow and/or mixed precipitation likely Wednesday, then rain Friday into next weekend possibly ends as snow; only modestly colder for following week before possible return of arctic air mid-January

Plain-language summary: 

 

It will be cold but dry this weekend except a little snow in southern areas late tonight into Sunday morning. A substantial but relatively gradual warmup will occur next week, contrary to expectations a few days ago. Light snow for southern areas is likely late on Monday. More widespread snow and/or mixed precipitation is likely on Wednesday, though precipitation amount and type is uncertain. Rain and a thaw is very likely Friday into next weekend before turning modestly colder but not colder than usual for January for following week, with possible snow or mixed precipitation in between. Arctic air may return in mid-January, perhaps with a long-awaited return of stormier weather, though the long-range forecast has been incredibly uncertain recently.

 

Meteorological discussion: 

 

Cold weekend, then gradual warmup, with light snow in southern areas early Sunday and late Monday; likely snow and/or mixed precipitation on Wednesday but precipitation intensity and type are uncertain

 

While models have shown signals of stormy and snowy weather patterns in the long-range this winter, they have mostly not materialized other than the big rainstorm a week before Christmas and the post-Christmas icing event. The big snowstorm is still elusive for most of the region despite having the coldest December since 2017 or even 2000 for most. This weekend will be cold, but fittingly mostly dry now that it is cold, except for intermittent light snow in southern areas tonight into Sunday morning from a weak elongated disturbance. Then, the upper-level ridging in the western U.S. breaks down, with upper-level troughing coming into the West Coast from the eastern Pacific, extending all the way to the Northwest Territories (-PNA). Combined with high-latitude blocking collapsing sooner than earlier expected (NAO and AO trending toward neutral), this will lead to mild Pacific air to flood most of North America by later next week, in contrast to all model expectations several days ago, though it will be a rather gradual process. Before that though, the warm advection combined with a weak disturbance will lead to a weakening area of light snow moving eastward from the Great Lakes Sunday night into Monday, though there may be little if any snow from Lake Champlain on northeastward. Weak warm advection will continue through Wednesday, with another disturbance likely to bring some snow or possibly mixed precipitation (given the milder air) into the region, though the strength of the disturbance, which is rather uncertain, will determine the intensity and type of precipitation. A stronger disturbance will produce heavier precipitation but will also advect more warm air into the region, leading to a farther north rain/snow line. Given the antecedent low-level cold air, a narrow zone of freezing rain is also possible, though it is unlikely to be nearly of as the same magnitude as last Monday's icing event.

 

Source: TropicalTidbits

 

Source: Climate Prediction Center

 

 

Mild with rain and a thaw likely Friday into next weekend, possibly ending as snow

 

After Wednesday, the weather pattern further amplifies, with a stout upper-level trough and ridge in western and eastern North America respectively. With the cold air in our region already stale and getting scoured out, the next storm that finally ejects out of the southern Rockies next Thursday and likely reaches our region around next Friday or possibly Saturday will likely be rain area-wide. It's ironic, since it has been hard to get any moisture-rich disturbances from the southern jet to move northeastward into our region this winter, and now that there is one, the cold air is routed out so thoroughly that even a relatively favorable track will yield rain. For now, it appears unlikely to get warm enough to melt the snow cover away like the mid-December thaw. The upper-level ridge could be strong enough that the storm's cold front stalls and allow another storm from the southwest to reach our region, perhaps with just enough cold air for snow for at least some. Arctic air is not required to get snow in January. 

 

Source: TropicalTidbits

 

 

Modestly colder but not arctic cold for following week, perhaps drier

 

It appears to get modestly colder afterward, but unlike in December, Canada does not look nearly as cold this time, and temperatures could still be slightly above average. Nonetheless, given that it is January, this will be cold enough to snow, provided that there are not additional amplified storms ejecting out of the Rockies. The models have had a really hard time figuring out the long-range weather pattern, so anything beyond this point has a very high uncertainty. It could just quickly dry out with an upper-level ridge over western and central Canada providing suppressive and dry but not particularly cold northwest flow as the real cold air staying well to the north. The majority of model guidance shows this scenario, which would only allow for moisture-starved Alberta clippers to reach our region, and given the inability for any moisture-rich southern jet disturbance to reach our region with any decent cold air, this would not be surprising.

 

Source: TropicalTidbits

 

 

Source: TropicalTidbits

 

 

Perhaps arctic air returns with more potential storminess starting mid-January, but very uncertain 

 

There are some signs of Alaskan upper-level ridging allowing for more arctic air and central North American upper-level troughing starting in mid-January, as well as a more amplified synoptic configuration being slightly more favorable for the more classic storm track from the southwest bringing more substantial snows to our region, but this is very uncertain given the chaotic run-to-run changes in model guidance.

 

Source: TropicalTidbits