Colorado State University (CSU) researchers on July 6 increased their Atlantic hurricane forecast for the second time this year. They now call for an above-average Atlantic basin hurricane season in 2023. However, they note that uncertainty with this outlook is larger than normal.
In June, CSU predicted a near-average hurricane season. In April, CSU predicted a slightly below-average season.
NEW NUMBERS
CSU now estimates that 2023 will have a total of:
- 18 named storms (average is 14.4)
- 90 named storm days (average is 69.4)
- 9 hurricanes (average is 7.2)
- 35 hurricane days (average is 27)
- 4 major (Category 3, 4 or 5) hurricanes (average is 3.2)
- 9 major hurricane days (average is 7.4)
These numbers include the four named storms that have formed already this year (January subtropical storm, Arlene, Bret and Cindy).
LANDFALL PROBABILITIES
The probability of U.S. major hurricane landfall is nowestimated to be above the long-period average. The probabilities for at least one major (Category 3, 4 or 5)hurricane landfall on each of the following coastalareas after July 5 are:
1) Entire continental U.S. coastline: 50% (full-season average from 1880–2020 is 43%)
2) U.S. East Coast including Peninsular Florida (south and east of Cedar Key, Florida): 25% (full-season average from 1880–2020 is 21%)
3) Gulf Coast from the Florida Panhandle (west and north of Cedar Key, Florida) westward to Brownsville, Texas: 32% (full-season average from 1880–2020 is 27%)
FACTORS BEHIND THE INCREASES
CSU reported that the tropical Pacific is currently characterized by El Niño conditions. However,the intensity of the El Niño for the remainder of the hurricane season remains unclear, although a moderate to strong event seems relatively likely.
El Niño typically reduces Atlantic hurricane activity through increases in vertical wind shear. However, sea surface temperatures in the eastern and central tropical Atlantic are now at record levels. So, despite the high potential for an El Niño, the impacts on tropical Atlantic/Caribbean vertical wind shear may not be as strong as is typically experienced given the extremely warm Atlantic.
See the full CSU July hurricane forecast here.
Source: CSU
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