It's a little late to talk about the 2020 hurricane outlook but not the review of the 2020 season. There are still about 30 days (through 30 November) in the 2021 Atlantic, central Pacific and eastern Pacific hurricane season. CNN has provided 'fast facts' on the 2021 Atlantic Hurricane season.
Eva Limpiec has assembled this CRS Insight report (13 October 2021): 2021 Hurricane Outlook and Review of 2020 Hurricane Season.
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Note that Insight reports have embedded likes which may not be functional here. Read the report online (click on the titles above) to get link functionality. Click on the graphics to enlarge them. In the Pacific, hurricanes are typically called cyclones. The entire report is reproduced here.
Introduction
The potential for widespread storm destruction to the United States underscores the value of timely tropical cyclone forecasts. The National Oceanic and Atmospheric Administration (NOAA) is responsible for issuing tropical cyclone forecasts, including track, intensity, storm surge, and rainfall.
NOAA defines a tropical cyclone as a “rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation.” According to NOAA, tropical cyclones include
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Tropical depressions—maximum sustained winds of ≤ 38 miles per hour (mph).
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Tropical storms—maximum sustained winds of 39-73 mph. NOAA typically names a storm once it reaches this strength.
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Hurricanes—maximum sustained winds of ≥ 74 mph, corresponding to a category 1 or 2 on the Saffir-Simpson Hurricane Wind Scale. Hurricanes are called typhoons or cyclones in other parts of the world.
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Major hurricanes—maximum sustained winds of ≥111 mph, corresponding to a category 3, 4, or 5.
NOAA releases seasonal hurricane outlooks relevant to the United States, including the north Atlantic, eastern Pacific, and central Pacific oceans, before each hurricane season begins. Although outlook titles refer to hurricanes, outlooks include information on potential named storms, hurricanes, and major hurricanes. The Atlantic and central Pacific seasons run from June 1 through November 30; the eastern Pacific season begins May 15. Tropical cyclones, however, may form outside of these timeframes. In August, NOAA typically updates the Atlantic outlook but not the Pacific outlooks. Multiple nonfederal entities also publish outlooks. These forecasts rely, in part, on NOAA’s collected and shared information.
2021 Hurricane Season Outlooks
In May 2021, NOAA issued its initial 2021 Atlantic hurricane outlook (Table 1), indicating a 60% likelihood of an above-normal season rather than a near- (30%) or below-normal season (10%). The predicted number of named storms, hurricanes, and major hurricanes was similar to the number initially predicted for the 2020 Atlantic hurricane season, but NOAA forecasters did not expect 2021 to be as “busy” as 2020. In its August 2021 update, NOAA increased the likelihood of an above-average season to 65% and adjusted the ranges of expected named storms and hurricanes but retained its original number of major hurricanes (Table 1). El Niño-Southern Oscillation conditions are currently in the neutral phase, with the possibility of La Niña later in the season, according to NOAA; both phases support high hurricane activity.
NOAA released its 2021 outlooks for the eastern (Table 2) and central Pacific hurricane seasons in May 2021. NOAA anticipated both regions likely would experience below-normal seasons (45%) rather than near- (35%) or above-normal seasons (20%).
NOAA predicted the central Pacific would experience two to five tropical cyclones in 2021. The central Pacific basin averaged four to five tropical cyclones per year between 1991 and 2020.
2020 Hurricane Season
In May 2020, NOAA issued its initial 2020 Atlantic hurricane season outlook (Table 3), indicating an above-normal season (60%). Its August 2020 outlook increased the likelihood of an above-normal season to 85%.
Since 2016, a tropical cyclone has formed before the June 1 start of the hurricane season (e.g., tropical storms Arthur and Bertha formed in May 2020). The 2020 Atlantic hurricane season (Figure 1) was noteworthy for the
most named storms (30),
second-highest number of hurricanes (14),
most number of landfalling named storms (11), with 4 coming ashore in Louisiana,
second-ever use of the Greek alphabet to supplement the 21-name Atlantic storm list, and
fifth consecutive year with an above-normal Atlantic hurricane season, totaling 18 above- normal seasons in the past 26 seasons. NOAA attributed the increased hurricane activity to the warm phase of the Atlantic Multidecadal Oscillation, which began in 1995. Such active eras in the Atlantic basin historically have lasted 25-40 years.
NOAA released its 2020 eastern Pacific (Table 4) and central Pacific hurricane outlooks in May 2020, anticipating these regions likely would experience near- (40%) to below-normal (35%) seasons, with above-normal seasons less likely to occur (25%).
The 2020 eastern Pacific hurricane season began when Tropical Depression One-E formed in April—the earliest tropical cyclone to form since the satellite record began in 1966. The season featured three major hurricanes: Douglas, Genevieve, and Marie.
NOAA predicted two to six tropical cyclones in the central Pacific during the 2020 hurricane season. The actual 2020 central Pacific season included two tropical cyclones in the basin: Boris and Douglas (Figure 3).
Enjoy Halloween!
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