This just-released outlook for the winter months of December-January-February calls for a cold and occasionally snowy late winter for sizeable parts of the Northern Plains, Midwest, and Great Lakes regions.
Blue = Colder Than Normal Brown = Warmer Than Normal
Green = Wetter Than Normal Brown = Drier Than Normal
Let’s discuss a number of weather features that could influence the 1- and 3-month outlooks. These include:
Climatology and an Increasingly Active Jet Stream
In the map at right, areas shaded in blue and green receive a relatively-higher amount of precipitation in December while areas shaded in red receive less.
From a climatological perspective, precipitation is enhanced across the Pacific Northwest (PNW) as well as parts of the Southeast. Much lesser amounts of precipitation tend to fall over the Plains.
Often, winter does not settle in until late December. A battle between mild and colder air can occur early in December with a secondary severe weather season over parts of the South.
ENSO Neutral conditions are expected to persist well into 2020. The past weak El Niño (Region Niño 3.4) has ended and should not have any significant impact on winter weather.
However, a persistent area of unusually-warm water over the North Pacific is likely to influence the position of the jet stream, and thereby temperature and precipitation anomalies.
It’s possible that this “wavy” jet stream pattern could emerge from time to time resulting in unusually-mild coastal temperatures and an unusually-cold middle U.S.
Despite the recent extremely-cold late Fall, a study of past winter temperature data shows that winter is warming over the entire U.S.