2022 Tropical Summer Outlook
2022 Tropical Season and Summer Outlook
2022 Tropical Season and Summertime Outlook
Current sea surface temperature (SST) anomalies with La Nina (colder-than-normal) conditions across much of the tropical Pacific Ocean and also off the west coast of Africa. There is warmer-than-normal water across much of the western Atlantic, Caribbean Sea and Gulf of Mexico. Map courtesy NOAA, tropicaltidbits.com
Overview
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.
Three parameters that factored into this year’s tropical outlook include (1) the continuation of La Nina conditions in the tropical Pacific Ocean for the third straight season, (2) warmer-than-normal sea surface temperatures in parts of the western tropical Atlantic Ocean and (3) colder-than-normal water off the west coast of Africa. The lack of an El Nino (i.e., warmer-than-normal water) in the tropical Pacific and the warmer-than-normal water in some of the “breeding ground” region of the tropical Atlantic tend to favor a more active tropical season in the Atlantic Basin; however, the colder waters off of Africa’s west coast will be a limiting factor.
A list of names to be used for tropical storms/hurricanes in the 2022 Atlantic Basin tropical season. (Note – the Atlantic Basin includes the Caribbean Sea and Gulf of Mexico in addition to the Atlantic Ocean).
Executive Summary
Slightly above-normal tropical season in the Atlantic Basin
Not quite as active as the last two years
Continuation of La Nina conditions in the equatorial Pacific Ocean
Warmer-than-normal water in parts of the western tropical Atlantic
Colder-than-normal water off the west coast of Africa
An analysis of “analog” years suggests the following:
Quite warm and dry conditions for the Northern and Central Plains
Slightly warmer-than-normal in the Mid-Atlantic/Northeast US; near normal temperatures in the Southeast
Slightly wetter-than-normal across much of the Eastern third
Recap of Recent Active Years in the Atlantic Basin
2021 Atlantic Basin summary map of storm tracks (plot courtesy Wikipedia)
The 2020 and 2021 Atlantic hurricane seasons were quite active with above the normal number of named storms, number of hurricanes and number of “major” hurricanes. Specifically, the 2020 tropical season featured a whopping 30 named storms with 14 of those reaching hurricane status and 7 of those “major” classification status. In fact, the 2020 tropical season was so active in the Atlantic Basin, the Greek alphabet had to be used for the naming of storms for only the second time – the first being in 2005. It will, however, be the last time ever for the Greek alphabet to be utilized in the naming convention as the World Meteorological Organization has decided to no longer use these letters to avoid apparent confusion on the part of the public. In 2021, there were 21 named storms of which 7 became classified as “hurricanes” and of those 4 climbed to “major” status. Interestingly, while the Atlantic Basin featured back-to-back active tropical seasons in 2020 and 2021, the much larger Pacific Ocean experienced consecutive quieter-than-normal tropical seasons.
La Nina Conditions in the Tropical Pacific Ocean
Compilation of computer model forecasts for El Nino Southern Oscillation (ENSO) state for the rest of 2022 with most continuing with La Nina conditions albeit some weakening as the summer season progresses. The graph shows forecasts made by dynamical and statistical models for sea surface temperature (SST) anomalies in the Nino “3.4” region for nine overlapping 3-month periods. Plot courtesy International Research Institute/CPC, NOAA, ECMWF, JMA
What goes on in the tropical Pacific Ocean does indeed have an impact on tropical activity in the Atlantic Ocean. El Nino, which refers to warmer-than-normal waters in the equatorial Pacific Ocean, affects global weather patterns and it tends to be an inhibiting factor for tropical storm formation/intensification in the Atlantic Basin. First, El Nino tends to produce faster-than-usual high-altitude winds over the tropical Atlantic Ocean and this increase in wind shear (change of wind speed with height) is hostile to the development or maintenance of tropical storms. In addition, El Nino tends to result in sinking motion over parts of the Atlantic Basin which also is hostile to tropical storm formation/intensification.
On the other hand, La Nina conditions in the equatorial part of the Pacific Ocean usually correlates with weaker wind shear over the breeding grounds of the tropical Atlantic Ocean and this leads to a more favorable environment for the development/intensification of tropical activity. La Nina formed in the spring of 2020 and has maintained its strength into 2022 and looks like it will be an important factor for the third consecutive tropical season. Numerous computer models forecast a transition of a moderate strength La Nina this spring to a weaker La Nina in the summer and they generally tend to continue maintain this same type of sea surface temperature pattern into the fall.
The North American Multi-Model Ensemble (NMME) forecast map of sea surface temperature anomalies is shown for the August/September/October 2022 period. The North American Multi-Model Ensemble is a multi-model, seasonal forecasting system consisting of coupled models from North American modeling centers including NOAA/NCEP, NOAA/GFDL, IRI, NCAR, NASA, and Canada's CMC. Map courtesy NOAA, tropicaltidbits.com
Mixed Signals in the Atlantic Ocean
Not only are Pacific Ocean sea surface temperatures important in terms of its potential impact on tropical activity in the Atlantic Basin, but Atlantic Ocean water temperatures are crucial and play more of a direct role in the prospects for formation/intensification of tropical storms. Sea surface temperatures of >80°F are generally considered to be a necessary condition for the formation of tropical storms in the Atlantic Basin. As a result, above-normal sea surface temperatures are more favorable for the formation and intensification of tropical storms as waves trek westward over the tropical Atlantic from western Africa. On the other hand, colder-than-normal sea surface temperatures in the Atlantic Ocean will tend to suppress tropical activity.
Indeed, there are mixed signals with respect to the water temperatures across the Atlantic Ocean as we approach the summer tropical season. First, the water in much of the western tropical Atlantic is generally warmer-than-normal as we close in on tropical season and it is as well in parts of the Gulf of Mexico and Caribbean Sea. Signs point to these sea surface temperature anomaly patterns continuing during the next several months – quite favorable for the formation/intensification of tropical storm activity in the Atlantic Basin.
The pockets of warmer-than-normal sea surface temperatures near the southern and eastern US coastlines make this part of the nation quite vulnerable to tropical hits this season; especially, when “home-grown” systems tend to dominate.(What I refer to as “home-grown” systems are those which form over the Gulf of Mexico or the far western Atlantic Ocean as compared with those that travel westward from western Africa and towards the US).These “home-grown” type systems generally tend to dominate during the latter stages of an Atlantic Basin tropical season. Meanwhile, the water off the west coast of Africa is colder-than-normal and this will tend to suppress tropical activity; especially, with the “African wave” that typically rides to the west in the trade winds from the land mass of Africa to over the eastern Atlantic Ocean.
Signals from Analog Years and Summertime Outlook
Based largely upon the expectation of a continuation of La Nina this summer and fall, there are seven analog years that I have selected which featured similar sea surface temperature anomalies and trends. When averaged together, these seven analog years featured slightly above-normal tropical activity in the Atlantic Basin. The seven analog years listed here include the number of named storms, number of minimal hurricanes, and the number of “major” hurricanes in each given year: 1975 (9/6/3), 1970 (14/7/2), 2011 (19/7/4), 2010 (19/12/5), 2013 (14/2/0), 2020 (30/14/7) and 2021 (21/7/4).
The seven analog years that I have selected based on comparison with sea surface temperature anomaly patterns featured warmer-than-normal conditions across much of the eastern half of the nation with especially warm weather across the Northern and Central Plains. In terms of precipitation, wetter-than-normal weather took place across much of the eastern third of the nation during these analog years and it was drier-than-normal in the Plains and much of Florida (right plot). Maps courtesy NOAA
In the Mid-Atlantic region, these seven analog years generally featured warmer-than-normal temperatures in the June through August time frame. Specifically, in terms of temperature anomalies, I expect the summer season to average somewhere in the +1.0 to 2.0 range in the Mid-Atlantic region. Elsewhere, there is reason to believe that the Northern and Central Plains could experience much warmer-than-normal conditions this summer based upon comparisons with these selected analog years and much drier-than-normal as well. Much of the eastern third of the nation may be in store for wetter-than-normal weather this summer which will follow a wetter-than-normal spring in most areas.