12 hours ago
How are the early weeks of hurricane season shaping up?
There's a fast ramp up in late summer and a fast cool down in early fall. Notice in the chart below how quickly the prevalence of hurricane and tropical storms becomes by mid-August but how fast it falls off later in September.
The average Atlantic hurricane season in terms of storms per date.
NOAA
Advertisement
Specifically, they show the number of hurricanes (yellow area) and combined named storms and hurricanes (red area) that occur on each calendar day over 100 years. The data has been smoothed using a 5-day running average centered on each calendar day.
For the Atlantic basin, the chart is based on data from the 77 years from 1944 to 2020 (starting at the beginning of the aircraft reconnaissance era) but normalized to 100 years. The peak of the Atlantic hurricane season is Sept. 10, with most activity occurring between mid-August and mid-October.
Related
:
Advertisement
There's already been some activity in the Pacific, which again is typical. Pacific hurricane season begins May 15, a full two weeks earlier than the Atlantic because water temperatures are more conducive earlier in the Eastern Pacific. The Pacific season is also more drawn out, with tropical activity remaining high from July through much of September. A similar chart to what I showed you for the Atlantic has a much more plateaued look in the Pacific.
Typical Eastern Pacific tropical storm and hurricane activity for an average tropical season.
NOAA
Back in the Atlantic, various influences will ignite more activity or suppress it.
If the trade winds are weak, there's not a lot of dry air, and water temperatures are above average, tropical storm formation can accelerate. If we have cooler-than-average temperatures off of Africa — think of it like a cousin to La Niña and call it the Atlantic La Niña — then that cooler-than-average water will limit tropical activity. Likewise, dry Sahara dust coming off the African continent will suppress thunderstorm development over the ocean, which you need to get tropical storms and hurricanes.
A blob of cooler-than-average water off the coast of Africa this June is likely contributing to suppressed tropical activity.
NOAA
Other influences on hurricane season include the Maiden-Julian Oscillation. This is a band of rotating tropical activity that occurs in the tropical Pacific Ocean. Depending on what part of its cycle the conveyor belt of thunderstorms associated with the MJO is located, it will enhance or suppress tropical energy. If an area of rising air forms over the Atlantic, then more thunderstorms will occur, perhaps leading to an organized tropical system.
Last year the first named storm, Alberto, brought heavy rain and flooding to Mexico and parts of Texas. The storm was named on June 17, well within the average.
Advertisement
Early season storms tend to form in the Western Caribbean, the Gulf of Mexico, or off the US southeast coast. The water is this region warms up faster than in the open Atlantic, where development is typically later in the summer and fall.
Typically during June, tropical storms and hurricanes emerge close to the mainland United States.
Boston Globe
This year, the National Weather Service has predicted there's a 90 percent chance of a near- or above-normal hurricane season. There's only a 10 percent chance that we will see fewer tropical systems than usual.
Once we do have a named storm, it will be called Andrea followed by Barry and Chantel. If some of these names seem familiar, it's because they are rotated on a five-year basis.
Unless a storm causes significant death and destruction, the name will be reused —otherwise it can be retired. In 2024, the World Meteorological Organization retired Beryl, Helene, and Milton from the Atlantic basin list and retired John from the Eastern Pacific list due to their destructive impacts.
Lastly, remember that we have not seen a hurricane reach New England shores since Bob in 1991, and we are statistically way overdue. It's not a bad idea to at least think about what you would do if a hurricane were to strike and make some preparations just in case.
