North Atlantic hurricane outlook tips mild as El Niño takes upper hand

The North Atlantic will likely generate 12 tropical storms in 2023, including six hurricanes of which 2 may achieve intense status, the UK government-supported research venture Tropical Storm Risk (TSR) has said in a reiteration of its early seasonal forecast.

“TSR maintains its forecast issued in early April and continues to predict North Atlantic hurricane activity in 2023 will be around 25% below the 1991-2020 30-year norm,” researchers said in the kick-off to the May update.

As at other forecasting institutions, TSR is juggling the net impact of storm-supportive surface sea temps against storm-suppressive wind conditions likely to form amid a moderate to strong El Niño event currently expected.

Water temps offer “small enhancing effect”, which is “expected to be over-ridden by the moderate suppressing effect” of the heightened trade winds, TSR analysts offer of their take on the key question.

The forecast is a fractional upward tweak from preliminary numbers issued in April, adding one tropical to its central forecast and increasing its call for accumulated cyclone energy (ACE) by 7%.

But even the latest count has a heavy preliminary ring to it and researchers warn that the outlook “has large uncertainties and the forecast skill at this range is low.”

The latest estimate for storm counts still falls visibly below the 10-year climate norm for 16.3 per season and the 30-year climate norm for 14.4.

Accumulated cyclone energy (ACE), now estimated at a likely reading of 90 in 2023, runs neighbourhood 26% below the 1991-2020 30-year climate norm. Researchers give only a 15% chance of an ACE reading to hit the top ten from the past 30 years. There's a 46% chance of hitting the middle ten and a 39% of hitting the bottom tercile.

The next TSR forecast update for the 2022 North Atlantic hurricane season is slated to be issued on Tuesday, July 6.

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