2022 Atlantic Hurricane Season Outlook
If it seems like hurricane season is just around the corner…that’s because it is. Starting on June 1st, the Atlantic Hurricane Season officially begins and will continue through the end of November. Since the 2016 hurricane season, the Atlantic has featured above average activity, and when looking at historical records that is an unprecedented stretch. For 2022, all signs point to another above average hurricane season with the major seasonal outlooks by Colorado State and NOAA (shown below in Figure 1) indicating an above average season. An ongoing La Nina and above average sea surface temperature configuration in the Atlantic are the two primary driving forces behind this reasoning. In the paragraphs below, we will dive into specifics regarding those driving factors for the Atlantic Hurricane Season.
The historic 2020 and active 2021 hurricane seasons featured a developing or maintaining La Nina event (one phase of the El Nino Southern Oscillation or ENSO). As a refresher, ENSO is a phase of either above average (El Nino) or below average (La Nina) sea surface temperatures, in the equatorial Pacific, from the normal baseline. We will likely be experiencing a very rare third year La Nina…which has only happened twice since 1950. While we are still within a difficult forecast period for ENSO, it appears that a weak to moderate La Nina should continue for the rest of 2022. Below are two forecasts from global models on ENSO (Figure 2 being the ECMWF or Euro and the Figure 3 being the CFS or Climate Forecast System; the individual lines are single model runs from an ensemble group for each model and the average stays near or below the -0.5⁰C threshold for La Nina):
The gradual warming of the ENSO regions from an April peak of -1.1⁰C should continue, but nearly all forecasts anticipate a weak La Nina (-0.5⁰C-0.9⁰C anomaly) to continue from June-October with perhaps a strengthening into the later fall months. So, what does a La Nina entail for the Atlantic Hurricane Season? Figure 4, below, is a map of sea surface temperatures compared to normal as of May 21st; yellow and orange indicates above average and blue indicates below average (credit to NOAA):
The outlined area in the red box on Figure 4 shows the below average sea surface temperatures in the Pacific. A large swath of cooler water continues to upwell across the entire equatorial Pacific Ocean. These cooler anomalies in the Pacific drive both stability in the Pacific and lower wind shear in the Atlantic basin (particularly the main development region and the Caribbean). Increased stability means that less storms will form (in the Pacific) reducing shear in the Atlantic and creating a more favorable environment in the Atlantic basin for development. In Figure 5 below, a composite forecast from several of the large global models, indicates a significant reduction in shear the tropical regions of the Atlantic basin compared to the seasonal normal during August, September, and October:
Figure 5: Credit to Eric Webb via Twitter.
Given the forecasted stability across the Pacific and the reduction in shear from Pacific storms/cooler ENSO regions, all signs point to a favorable environment across the Atlantic for higher than normal tropical activity.
Atlantic Sea Surface Temperatures
Sea surface temperatures in the Atlantic are running above average with some pockets of near average temperatures (mainly concentrated in the Caribbean). The large swath of above average sea surface temperatures extends from the subtropics to the main development region. It should be noted that hyperactive seasons are mostly correlated with main development region sea surface temperatures being above normal which is the region east of the Lesser Antilles and West of Africa. Below (Figure 6) is a map of the sea surface temperatures of the Atlantic and main development region (outlined in the purple box):
Figure 6 (Credit to NOAA).
As seen above, nearly the entire basin is above normal, but warm anomalies in the subtropics can sometimes counter a warm main development region leading to some instability issues. Tracking the sea surface temperature configuration as the season progresses will be important, but even with those concerns of a warm subtropical Atlantic potentially putting a lid on the deep tropics, the Gulf of Mexico is well above normal…even record warm. The recent trends of rapidly intensifying landfall hurricanes can be partially attributed to these very warm Gulf of Mexico waters and that will need to be watched closely with any storms that may make their way into the Gulf.
So, with the warm Atlantic Ocean and a La Nina, all signs point to an above average season…potentially well above average. But, the more granular details such as steering currents and landfall points cannot be determined so far in advance. All coastal residents and anyone with interests should remain aware that this season has the high likelihood to be active...much like every season we have seen since 2016…and impacts of landfalling storms can carry well inland. The Tennessee Valley Weather team will keep viewers abreast of any tropical mischief throughout the season.