Fall 2022 has arrived across the United States, and while most are drinking their Pumpkin Spice Latte’s, raking their yards, and enjoying the cooler weather, we are preparing for the arrival of the Winter season. Last year, early winter warmth got us off to a slow start as an upper-level ridge and well above average temperatures dominated the weather pattern through December before we started to see more of a Winter pattern take hold in January. Overall, several places finished the 2021-2022 season near average, like Detroit, who saw 91.8% of their normal snowfall. However, some areas did miss out, much like Indianapolis, who only received a measly 44.8% of their annual snowfall.
Now with the winter season rapidly approaching the question on everyone’s mind is “What can we expected this year?!”
ENSO – EL-NINO SOUTHERN OSCILLATION
As always, ENSO will play an integral role in the Winter season forecast for 2022-2023. As of September, we continue to see colder than average waters across much of the equatorial Pacific with the coldest being the Nino 4 and 3.4 regions, simply put, this means we are still in a La Niña (cold phase of ENSO) much like last year.
Into the next several months, La Niña should be a factor with a 70% chance of this pattern continuing from Nov – Jan and a 60% chance of the pattern continuing from December through February. However, forecasts do suggest that La Niña will continue to weaken slightly through the rest of the fall and winter. Probability guidance even suggest that there will be a 45% chance of seeing an ENSO Neutral pattern as soon as the January through March period which could also have impacts on the late winter early spring.
La Niña weather patterns tend to lead to warmer, wetter conditions across parts of the Midwest region with drier conditions across the southern US. We anticipate cooler, wetter conditions across the Pacific Northwest in this pattern thanks to the Pacific Jetstream.
However, there are still some unknowns about the latest season ENSO Neutral forecast. This could throw a wrench into the pattern for late Winter as the Neutral pattern tends to shift the polar jet stream further south which would bring higher confidence of colder air across much of the northern US, Midwest, and Northeast. It would also favor warm, wet conditions into the Southeast.
Using past weather conditions or patterns to forecast upcoming seasonal trends is especially important. Understanding the pattern, current and forecast ENSO Phase, and other factors can lead to a better understanding of what previous years closely resemble the upcoming one. This is called analog data, and it is a great forecasting tool. For the 2022-2023 season, we currently see three years that have a greater correlation with the upcoming winter season and two years that have a bit weaker correlation.
If we look at analog temperature anomalies, the data favors a colder-than-average winter across northern US, this will extend down into the Midwest and Northeast. The heart of the cold will focus into the Northern Plains and Upper-Midwest. More warmth could make its way into the southwestern portions of the nation.
Analog precipitation guidance suggests near average precipitation for a sizable portion of the US. However, more favorable dry areas would be along the West Coast and from the Gulf Coast into portions of the Carolinas.
While this method lends a lot of confidence to a forecast, there are still some caveats, especially this early. The ENSO forecast months in advance is never a sure thing and can rapidly change with not a lot of lead time. If this occurs, then the analog years that seem to fit the pattern now could really change by November or December.
SEASONAL FORECAST GUIDANCE
Seasonal forecast guidance tends to lend some additional confidence to the winter forecast but is also dependent on ENSO forecasts and other pattern drivers. However, it is also important to understand its limitations and biases when using it to make a forecast.
The latest seasonal forecast guidance suggest that the southern portions of the US will experience above average temperatures. Weather models indicate greater confidence for below-average temperatures across the far northern tier of the US, but some models do show more of the classic La Niña temperature forecast bringing Arctic intrusions down into the Midwest, as well.
Precipitation guidance from December through February looks much like a normal La Niña winter, as well. Guidance suggests above average precipitation into the northwest, Tennessee/Ohio Valley, and potentially into the Northeast. However, well-below-average precipitation is favored into the southeastern portions of the US.
Much of the guidance continues to favor more of a La Niña type look to the forecast this winter, this could allow this winter season to be reminiscent of this past year. That could also mean we start off the winter warm before we finally cool off into the New Year. In fact, seasonal forecast guidance would tend to lean in that direction. The greatest confidence in colder-than-average temperatures look to be across the northern portions of the US, perhaps extending down into the Midwest late winter. Above-average temperatures are likely into the South/Southeastern US.
The winter season could potentially start off dry once again, especially into the Midwest and Northeast. Better precipitation and snow chances could present themselves as we progress later into the season. Overall, weather experts favor above-average precipitation more into the Northwest, Northern US, Tennessee/Ohio Valley regions, perhaps shifting into the Deep South by late January into February.
While snowfall is hard to forecast from this point in the year, here are some early season thoughts. A northwest flow across the Northern Plains into the Midwest could allow for yet another active clipper season for those areas. Bigger events may once again start off in the Northern Plains region. If we shift more into an ENSO Neutral pattern late in winter, it could allow for better snow potential into the Mid-Atlantic states late season as the colder air shifts further south and the sub-tropical jet pushes moisture into the Southern/Southeastern US.
Overall, La Niña still looks to be the biggest player for the winter season and as previously stated could lead to a more similar year as this past winter. However, there are still unanswered questions heading into the next couple of months. Regardless, everyone will be prepared for whatever Mother Nature throws at us this year.