Last winter was generally warmer-than-normal in the Mid-Atlantic region with below-normal snowfall and 2024 began with a rather strong El Nino event in the tropical Pacific Ocean. However, those warmer-than-normal water temperatures have since flipped to below-normal and this upcoming winter season is quite likely to feature weak La Nina (colder-than-normal) conditions.

Numerous signs point to an active tropical season this year in the Atlantic Basin with more tropical storms, hurricanes, and “major” hurricanes compared to the long-term averages. The average number of named tropical storms in an Atlantic Basin tropical season is 14.4 with 7.2 of those reaching (minimal) hurricane status, and 3.2 becoming “major” (1991-2020 baseline period).

A major change has come to the tropical Pacific Ocean since last winter with respect to sea surface temperatures and this transformation will have a big impact on the upcoming winter. Specifically, above-normal sea surface temperatures (El Nino) have replaced the cooler-than-normal conditions (La Nina) of the previous winter. In fact, the tropical Pacific Ocean uncommonly featured “back-to-back-to-back” La Nina winters with cooler-than-normal water temperatures, but drastic changes began to take shape earlier this year.

Tropical activity is likely to be nearly normal this season in the Atlantic Basin with competing factors in the Atlantic and Pacific Oceans. In a normal Atlantic Basin tropical season, there are about 14 named storms, 7 hurricanes, and 3 of those actually attain “major” classification status (i.e., category 3 or higher on the Saffir-Simpson hurricane wind scale).

The past two winters have featured La Nina conditions in the equatorial part of the Pacific Ocean and all signs point to a third such event for the winter of 2022-2023. While “back-to-back-to-back” La Nina episodes are not unprecedented, they are rather uncommon and analog years suggest that the third winter in this extended oceanic event is typically colder-than-normal across much of the eastern half of the nation with the coldest core of the air centered over the Upper Midwest. In addition to La Nina, another factor considered in the 2022-2023 “Winter Outlook” is the stratospheric cooling that developed earlier this year in the southern hemisphere partly as a result of unusually high levels of water vapor that were injected aloft by the powerful Hunga Tonga volcanic eruption back in January. The connection between southern hemisphere stratospheric cooling and high-latitude blocking (negative NAO) patterns in the subsequent northern hemisphere winter season is investigated.

We are likely headed to another tropical season in the Atlantic Basin with more activity than usual, but not quite as active as the last couple of years. The average number of named storms in an Atlantic Basin tropical season is 14.4 with 7.2 of those reaching minimal hurricane status and 3.2 becoming “major” In comparison with the 1991-2020 baseline period). Based on the overall analysis of current and forecasted atmospheric and oceanic conditions, I expect around 18 named storms in the Atlantic Basin this tropical season with around 8 reaching hurricane status and of those perhaps as many as 4 to achieve “major” classification level.

The winter season of 2020-2021 featured La Nina conditions in the equatorial part of the Pacific Ocean which then weakened to near neutral status during the spring and summer of this year. New cooling has formed in the same region and it appears that a second year La Nina will take place for the upcoming winter season. Sea surface temperature anomalies in the central Pacific Ocean were but one of several factors considered in the 2021-2022 “Winter Outlook”.

Numerous factors have been examined for this year’s “Winter Outlook” including the strong prospects for a moderately strong La Nina event in the tropical Pacific Ocean, somewhat favorable signs for high-latitude blocking events, and an analysis of “analog” winters that featured similar oceanic conditions to today’s environment. Many signs point to colder-than-normal conditions this winter season across the northern US including in the Mid-Atlantic region and the virtually snowless winter of last year is quite likely not going to repeat itself.

The overall numbers are likely to be above average this year in terms of the number of tropical storms and hurricanes in the Atlantic Basin (includes the Caribbean Sea and Gulf of Mexico) with around 13 named tropical systems, 7 hurricanes, and 3 majors (i.e., category 3, 4 or 5 on the Saffir-Simpson Hurricane Wind Scale).

The Mid-Atlantic region should experience slightly colder-than-normal temperatures this winter season and slightly above-normal snowfall amounts based upon such factors described above as current sea surface temperature anomalies, the likelihood of high-latitude blocking events, and a comparison with analog years.

The overall numbers are likely to be slightly below-normal this year in terms of the number of tropical storms and hurricanes in the Atlantic Basin …

The current sea surface temperature anomaly pattern features a large and expanding area of warmer-than-normal conditions across the equatorial Pacific Ocean and warmer-than-normal water in the northern Pacific

The overall numbers are likely to be near normal this year in terms of the number of tropical storms and hurricanes in the Atlantic Basin (includes the Caribbean Sea and Gulf of Mexico)

Last winter was one in which warmer-than-normal temperatures prevailed in the I-95 corridor during the December, January and February time period.

The overall numbers are likely to be near normal this year in terms of the number of Atlantic Basin (includes the Caribbean Sea and Gulf of Mexico) tropical storms and the sea surface temperature pattern in the western Atlantic and Caribbean Sea makes the southern and eastern US somewhat vulnerable to “home-grown” tropical hits.

Last winter was one in which significantly warmer-than-normal temperatures prevailed in the Mid-Atlantic region largely as a result of a strong El Nino event in the tropical Pacific Ocean, but it also featured a blockbuster blizzard that boosted seasonal values to well above normal levels in the DC-to-Philly-to-New York City corridor.

The major factors involved with the "2016 Tropical and Mid-Atlantic Summertime Outlook" include a quickly weakening El Nino in the equatorial Pacific Ocean, the likelihood for the onset of La Nina by later in the summer, and the current “mixed” sea surface temperature signals across the Atlantic Ocean.

It looks like the Mid-Atlantic region is going to experience another snowy winter with numerous coastal storms – and there can even be a blockbuster snowstorm or two

The overall numbers are likely to be down this year in terms of the number of Atlantic Basin tropical storms, but the sea surface temperature pattern in the western Atlantic and Gulf of Mexico makes the U.S. east coast vulnerable to “home-grown” tropical hits

Looks like the Mid-Atlantic region - and much of the eastern half of the nation - is going to experience another cold and snowy winter…

The overall numbers may be down this year in terms of the number of Atlantic Basin tropical storms, but the sea surface temperature pattern in the western Atlantic and Gulf of Mexico makes the U.S. quite vulnerable to some late season tropical hits

Looks like the Mid-Atlantic region is leaning towards the colder and snowier side of normal for the upcoming winter of 2013-2014…

It looks like it’ll be an active Atlantic Basin tropical season in 2013 and, once again, the east coast is vulnerable to a direct hurricane hit and this includes the region from North Carolina to Maine

Looks like a cold and snowy winter compared to normal for the Mid-Atlantic region… Last winter will be remembered for its warmth and lack of snow in the Mid-Atlantic region as well as for much of the eastern half of the country

The summer of 2011 brought the Mid-Atlantic region hotter-than-normal weather and was quite active in the tropical Atlantic in terms of the number of named tropical storms

It appears that much of the Mid-Atlantic will experience above normal snowfall and colder-than-normal temperatures during the upcoming winter season