DISCUSSION: There is no question that as the 2019 – 2020 winter season continues to move forward from late December and on into early January, millions of people spread across coastal sections of the Northeast U.S. will be wondering when and if there will or will not be a “true Winter.” However, it goes without saying that year in and year out there are always many questions from people all over the world regarding whether a given Winter season will be at least partly consumed by snowy and colder conditions.
Often, meteorologists from across the operational and private sector will respectfully do their very best to answer such questions in an appropriate and an accurate fashion despite any and all criticism they expect to receive. Nonetheless, whether it is for energy trading companies, domestic and/or global travel concerns, this can be a challenging question to correctly answer for several reasons. And, it is quite important to understand a little bit about some of the reasons for why this task can be so challenging.
First, it is important to understand that during any given winter season there are several climatological patterns effect large-scale atmospheric flow regimes. More specifically, a few prime examples include the El Niño Southern Oscillation (ENSO) as well as the Arctic Oscillation (AO) are two major players with respect to global climate variability that affect the likelihood of there being or not being a storm track as well as longer duration temperature trends which are more favorable for winter storm development. The ENSO will have an influence on larger scale atmospheric flow regimes since whether there are warmer or cooler sea surface temperatures across the central to Eastern Pacific Ocean basin will be a direct link to the frequency of more ridge or trough dominated patterns across North America. Whenever there are more ridge-dominant atmospheric flow regimes in place across western to central portions of the United States, this can often be unfavorable for winter storm development along the U.S. East Coast. However, it is important to note that depending upon the latitudinal position of a given ridge or trough, this can allow or not allow colder air filter in towards higher calculated regions of the northeastern U.S. which under the right conditions can set the stage for winter storm potential. And, the AO is often the factor which will predominantly control whether or not colder air masses are unleashed on the contiguous United States based on the strength of the low-pressure system(s) in place at the time. The key reason for this is because whenever there is a winter storm threat, the most critical factor is the presence of a deep cold air mass in the general area where the corresponding low-pressure is expected to develop. This is a critical factor since without cold air, there will not be sufficient support for snowfall development over a long enough period.
Thus, as far as the next few to several weeks are concerned during the 2019 to 2020 winter season, it goes without saying that although the current larger scale setup is not favorable for winter storm potential, this can and could potentially change rather quickly over the next few weeks. This is simply because the atmosphere is always in a state of gradual or more rapid transition and that any given Intraseasonal pattern is never locked in place for more than a week or two (generally speaking) with some very common exceptions to this rule. The most common winter storm potential indicated that is looked for during a given winter season with respect to the U.S. East Coast is the presence of a blocking high pressure system over Greenland as well as persistent trough development across the central U.S. the reason for this is because more persistent trough development (i.e., to the north of the Gulf of Mexico) as well as the presence of persistent deep cold air can set the stage for winter storm threats in such (or comparably similar scenarios). Therefore, even though the current and upcoming larger scale atmospheric flow regime is more than likely going to remain unfavorable for winter storm development, the 2019 to 2020 winter season is just getting started and let us also remember that the climatological peak for winter storm development along the US East Coast is during the month of February.
So, before going ahead and writing off anything just yet, it is important to keep some of these helpful winter weather tidbits in mind as time moves along.
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©2019 Meteorologist Jordan Rabinowitz