This is a re-post from Yale Climate Connections by Jeff Masters
Residents of Hurricane Alley can anticipate an above-average Atlantic hurricane season in 2022, NOAA’s Climate Prediction Center said Tuesday, May 24. In its first seasonal forecast for 2022, NOAA predicted a 65% chance for an above-average Atlantic hurricane season, a 25% chance for an average season, and a 10% chance for a below-average season. NOAA gave a 70% likelihood of 14-21 named storms, 6-10 hurricanes, 3-6 major hurricanes (Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale), and an Accumulated Cyclone Energy (ACE) 115% – 200% of the median. Based on the midpoint of these ranges, NOAA called for 17.5 named storms, 8 hurricanes, and 4.5 major hurricanes. Those numbers are above the 1991-2020 seasonal averages of 14 named storms, 7 hurricanes, and 3 major hurricanes.
NOAA cited these main factors influencing its Atlantic forecast:
1) The likely continuation of La Niña conditions over the tropical Pacific Ocean [ENSO refers to El Niño/Southern Oscillation, which has three phases: El Niño, neutral, and La Niña]. El Niño suppresses hurricane development in the Atlantic by increasing the amount of vertical wind shear and dry, stable air that tends to prevail over the Main Development Region (MDR) for hurricanes, which includes the tropical North Atlantic Ocean and Caribbean Sea between 9.5°N and 21.5°N latitude. The latest monthly NOAA/IRI probabilistic ENSO forecast, issued May 19, calls for just a 4% chance of El Niño conditions during the peak August-September-October period of the Atlantic hurricane season, thus setting the stage for our seventh consecutive above-average Atlantic hurricane season.
2) Expected warmer-than-average sea-surface temperatures (SSTs) and weaker-than-average trade winds in the Main Development Region, along with below-average wind shear and an active West African monsoon. SSTs are currently near average in the MDR, but nearly all climate models predict SSTs to be above average in the MDR during August, September, and October.
NOAA issued these words of advice: “Hurricane-related disasters can occur whether the season is active or relatively quiet. It only takes one hurricane (or tropical storm) to cause a disaster. It is crucial that residents, businesses, and government agencies of coastal and near-coastal regions prepare for every hurricane season regardless of this, or any other, seasonal outlook.”
The April 6 forecast for the 2022 Atlantic hurricane season made by British private forecasting firm Tropical Storm Risk, Inc. (TSR) called for an above-average Atlantic hurricane season, but with less activity than the busy 2020 and 2021 seasons. For 2022, TSR predicted 18 named storms, 8 hurricanes, 4 intense hurricanes, and an Accumulated Cyclone Energy (ACE) of 138. The long-term averages for the past 72 years are 12.2 named storms, 6.4 hurricanes, 2.7 intense hurricanes, and an ACE of 105. TSR rated its skill level as low for these April forecasts – just 0-4% higher than a “no-skill” forecast made using climatology.
TSR predicted a 39% chance that the U.S. landfalling ACE index will be above average, a 40% chance it will be near average, and a 21% chance it will be below average. It projected four named storms will hit the U.S., two of them as hurricanes. The averages from 1950-2021 are 3.3 named storms and 1.5 hurricanes hitting the U.S. TSR rated its skill at making these April forecasts for U.S. landfalls at 1% – 12% higher than a “no-skill” forecast made using climatology. The next TSR forecast is to be issued on May 31.
As discussed in a previous post, the April 7 forecast from the hurricane forecasting team at Colorado State University (CSU) called for an active Atlantic hurricane season with 19 named storms, 9 hurricanes, 4 intense hurricanes, and an Accumulated Cyclone Energy (ACE) of 160. The CSU outlook also predicted the odds that a major hurricane will hit the U.S. at about 71% (the long-term average is 52%). The CSU team gave a 47% chance for a major hurricane to hit the East Coast or Florida Peninsula (the long-term average is 31%), and a 46% chance for the Gulf Coast (the long-term average is 30%). The outlook included a 60% chance that at least one major hurricane will hit in the Caribbean basin (the long-term average is 42%). The next CSU forecast is to be issued on June 2.
The May 23 forecast from the UK Met Office called for an active Atlantic hurricane season with 18 named storms, 9 hurricanes, 4 major hurricanes, and an Accumulated Cyclone Energy (ACE) of 176. The forecast was made using information from the Met Office seasonal prediction system, GloSea6, an ensemble prediction system based on a fully coupled ocean-atmosphere general circulation model (GCM).
The April 14 forecast from The Weather Company called for an active Atlantic hurricane season with 20 named storms, 8 hurricanes, and 4 major hurricanes. Dr. Todd Crawford, the author of the TWC outlook, said it can best be summarized as “active, similar to 2021, nothing like 2020.” The 2021 Atlantic hurricane season had 21 named storms and seven hurricanes, and the 2020 season had a record 30 named storms.
The May 9 forecast from Penn State’s Michael Mann, Daniel Brouillette, and alumnus Michael Kozar called for an above-average Atlantic hurricane season with 14.9 named storms (expected range: 11 to 19). Their prediction was made using statistics of how past hurricane seasons have behaved in response to SSTs, ENSO, the North Atlantic Oscillation (NAO), and other factors. Their statistical model assumed that the early-May +0.65 degree Celsius departure from average temperature in the MDR would persist throughout hurricane season, that weak La Niña conditions would persist through the fall, and that climatological mean conditions for the NAO would exist in the fall/winter of 2022.
The Penn State forecast team has been making Atlantic hurricane season forecasts since 2007, and these predictions have done well, except in 2012, 2018, 2019, and 2021:
2007 prediction: 15 named storms, Actual: 15
2009 prediction: 12 named storms, Actual: 9
2010 prediction: 23 named storms, Actual: 19
2011 prediction: 16 named storms, Actual: 19
2012 prediction: 11 named storms, Actual: 19
2013 prediction: 16 named storms, Actual: 14
2014 prediction: 9 named storms, Actual: 8
2015 prediction: 7 named storms, Actual: 11
2016 prediction: 19 named storms, Actual: 15
2017 prediction: 15 named storms, Actual: 17
2018 prediction: 10 named storms, Actual: 15
2019 prediction: 10 named storms, Actual: 18
2020 prediction: 20 named storms, Actual: 30
2021 prediction: 12 named storms, Actual: 21
NOAA predicted a below-average 2022 hurricane season in both the eastern Pacific (for storms affecting Mexico) and the central Pacific (for storms affecting Hawaii). The eastern Pacific outlook calls for a 70% probability of 10-17 named storms, with 4-8 are expected to become hurricanes, including 0-3 major hurricanes. An ACE of 45% – 100% of the median was also predicted. Again here using the midpoint of these ranges, NOAA is calling for 13.5 named storms, 6 hurricanes, and 1.5 major hurricanes, falling below the 1991-2020 averages of 15 named storms, 8 hurricanes, and 4 major hurricanes.
The central Pacific outlook calls for a 70% probability of 2-4 tropical cyclones (which includes tropical depressions, tropical storms, and hurricanes). A near-average season there has 4-5 tropical cyclones. La Niña conditions typically lead to relatively quiet hurricane seasons in both the eastern and central Pacific as a result of cooler-than-average ocean temperatures and higher wind shear.
Recent runs of the GFS and European models and their ensemble members have been predicting that a broad area of low pressure in the eastern Pacific, a few hundred miles south of the coast of southeastern Mexico, is likely to develop into a tropical depression or tropical storm by the weekend, with the National Hurricane Center (NHC) giving the system five-day formation odds of 70% in its 2 p.m. EDT Tuesday Tropical Weather Outlook. The system, predicted to move west-northwest to northwest at 5-10 mph, has the potential to make landfall in Mexico as early as Sunday, May 29. The first name on the eastern Pacific list of storms is Agatha.
The system has the potential to cross over Mexico and enter the southern Gulf of Mexico’s Bay of Campeche early next week, when it could become the Atlantic’s first named storm of the year. The first name on the Atlantic list of storms is Alex.
If it does cross into the Gulf of Mexico, the system likely will become embedded by mid-week in a larger area of low pressure over Central America called a “Central American Gyre” (CAG). The counter-clockwise steering flow of the Central American Gyre could push the system back over Mexico, leading to no threat to the U.S. Gulf Coast.
Central American Gyres can spawn a tropical cyclone on their own, though it usually requires many days for this to occur; category 5 Hurricane Michael of October 2018 had its origins in a long-lived CAG, for example. Recent runs of the GFS model have been predicting that the current CAG may be capable of spawning a tropical depression in the Western Caribbean by late next week. However, this model did not do well in its predictions for a similar event to occur last week, and the GFS model predictions should be viewed skeptically until the European and/or UKMET models make a similar forecast.
Also see: How to make an evacuation plan
Bob Henson contributed to this post.
Posted by Guest Author on Wednesday, 1 June, 2022
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