Hurricane Experts Issue Updated Outlook for the 2024 Season

Colorado State University forecasters continue to call for a hyperactive Atlantic hurricane season

Hurricane Maria on September 21, 2017, taken by European Space Agency astronaut Paolo Nespoli aboard the International Space Station. Credit: European Space Agency/NASA

Experts at Colorado State University (CSU) – the pioneers of seasonal hurricane forecasts – issued their June update to their 2024 hurricane season outlook on Thursday. The forecast team continues to predict an extremely active hurricane season in the months ahead with 23 named storms, 11 hurricanes, and 5 Category 3 or stronger hurricanes.

This is well above the 30-year average of 14 named storms, 7 hurricanes, and 3 Category 3 or stronger hurricanes in the Atlantic. Like their initial outlook issued in April, this is the most aggressive prediction ever made by the forecast team in 41 years of seasonal hurricane outlooks.

Experts at CSU left their forecast numbers unchanged from April, but the consistent forecast indicates high confidence in this year’s outlook, which they note in their June report. Outlooks issued during the hurricane season have historically shown considerable skill and higher skill scores than pre-season forecasts.

Forecast skill for seasonal hurricane outlooks issued in April, June, and August by Colorado State University. Higher numbers indicate higher skill. Forecasts issued over the past decade during the hurricane season (June and August) show significant skill. Credit: Dr. Phil Klotzbach/Colorado State University.

The outlook comes on the heels of a blistering month of record warm sea surface temperatures throughout the tropical waters of the Atlantic. CSU researchers note the unseasonably warm water temperatures in the far eastern tropical and subtropical Atlantic, which have been shown to be strong predictors of forthcoming hurricane season activity.

The map on the left shows the relationship between June sea surface temperatures and overall hurricane season activity, as measured by the Accumulated Cyclone Energy or ACE. The warmest colors shown in the black box over the eastern Atlantic indicate a high correlation between ACE and sea surface temperatures for June. The map on the right shows the sea surface temperature departure from average since early May. The waters in the black box are generally much warmer than average, supporting a forecast for an active hurricane season.

Additionally, the waters of the eastern Pacific around the equator continue to quickly cool, signaling a transition to La Niña conditions for the fall. Government scientists are predicting the onset of La Niña in the July to September time frame, coinciding with the peak months of hurricane season.

A La Niña in the eastern Pacific would act to reduce hostile wind shear in the Atlantic, especially in the western part of the Atlantic near land areas. For this reason, CSU forecasters also indicate higher odds of landfalling Atlantic hurricanes in 2024.

Regardless of the seasonal hurricane forecasts, it only takes one bad hurricane strike to make for a bad season. So far the Atlantic hurricane season has gifted us a leisurely start, but this surely won’t last long. Florida’s disaster preparedness sales tax holiday runs through this Friday, so take the opportunity to buy any last-minute preparedness items – including expensive generators – without having to pay taxes.

Heavy rain moving in over South Florida

The multi-day heavy rainfall event we’ve been advertising since last week has begun across South Florida. Rounds of slow-moving tropical rains are anticipated through the week and will bring the threat for flash flooding, especially to urban and low-lying areas. All of South Florida is under a flood watch until at least Wednesday evening, and it’s likely the flood watch will be extended deeper into the workweek.

New area to watch off the southeast U.S.

Though no tropical development is expected with the unsettled weather near Florida because of strong jet stream winds, we could see the jet stream energize an area of low pressure along the stalled front off the southeast U.S. by Friday into the weekend.

The National Hurricane Center as of Tuesday morning was indicating low odds of tropical formation with this area – designated Invest 90L – by later this week.

Any system that tries to take shape off the southeast U.S. would begin with subtropical characteristics but could briefly transition into a tropical system while over the warm Gulf stream. If anything forms, it should stay weak and short-lived as it moves away from the U.S.