NOAA's final pre-season update aligns with CAHM24

CAHM24’s 70% range of hurricanes anticipates NOAA’s final pre-season update.1

NOAA’s 70% interval [8 to 13 hurricanes] released on 23 May coincides with the level to which CAHM24 updated after release of the 20 May Bulletin.

According to current CAHM24 price-probabilities the mathematical expectation of the number of hurricanes this season is 9.8.2

As detailed in our explainer, CAHM24 pertains to tropical cyclones achieving sustained wind speeds of at least 74 mph (i.e. ‘hurricanes’), which are classed as Category 1 or higher on the Saffir-Simpson Hurricane Wind Scale.

During the 30-year period from 1991 to 2020, the average Atlantic hurricane season had 14 named storms, 7 hurricanes, and 3 major hurricanes (Category 3, 4, or 5, with maximum sustained wind speeds ≥111 mph).3

NOAA’s 23 May outlook predicts an 85% chance of an above-normal season, a 10% chance of a near-normal season and a 5% chance of a below-normal season.1

The upcoming Atlantic hurricane season is expected to have above-normal activity due to a confluence of factors, including near-record warm ocean temperatures in the Atlantic Ocean, development of La Nina conditions in the Pacific, reduced Atlantic trade winds and less wind shear, all of which tend to favor tropical storm formation.1

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  2. The CAHM24 mean places all probability weight in the ≥20 ’tail’ on 20. Hence the mean should be interpreted as “≥9.8”. ↩︎

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