Atlantic looks ‘near normal’ for hurricanes, but drivers well split: NOAA
The Atlantic is set to deliver a “near normal” season of storm activity in 2023, with a 70% chance of between 12 and 17 named storms, including 5 to 9 hurricanes, but with caveat for the wildcards built into seasons with a mixed set of drivers, researchers at the National Oceanic and Atmospheric Administration (NOAA) have said.
Of the 5 to 9 hurricanes forecasted, between one and four could pack the punch of a major hurricane. Measured by accumulated cyclone energy, the season has that 70% chance of falling within the range of 70 to 145% of the median. NOAA does not do landfall probabilities.
As with other early views to the season, the toning down of expected activity is primarily attributed to the high potential for a shift into El Niño conditions, said to increase the wind shear that prevents storm formation. A rare three-year run of La Niña had helped turbo-boost long-running high-activity era for Atlantic hurricanes in place since 1995.
The most recent NOAA forecast indicates a 93% chance that El Niño conditions will develop through the hurricane season.
But offsetting factors for higher activity are also present. Those factors include a likelihood for above normal west African monsoon that kick off many Atlantic events, a more conducive African easterly jet, weaker trade winds plus warmer than normal Atlantic and Caribbean water temperatures, which can fuel storms once underway.
The added threat under such conditions: seasons built on “competing or non-reinforcing climate factors” have a historical tendency to produce Atlantic hurricane seasons “with a wide range of activity.”
The overall likelihood of the “near normal” scenario was set at 40%, with the risk of running either more or less severe evenly distributed, authors noted. That, NOAA notes, is 14 named storms, 7 hurricanes and 3 major hurricanes. In terms of ACR, "near normal" means between 75.4% and 130% of the 1951-2020 median.
For the 2023 hurricane season, NOAA will begin to work from a brand new Hurricane Analysis and Forecast System (HAFS) which will work alongside existing models before taking the lead in NOAA's forecasting. NOAA claims that retrospective studies give the new model a 10-15% improvement in track record over the current system. NOAA has also upgraded its storm surge model.
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