Hurricane season not quite lagging, yet

Past three years of hyperactive starts makes it seem quieter than it really is historically

History of tropical storms and hurricanes Tropical cyclone season lies ahead

By Kirk Mellish

We have not seen a named tropical cyclone since Colin July 3rd for the Atlantic/Caribbean. Historically this quiet period is not unusual for the Atlantic. Even for the first week of August, we typically only see storm formations on average once every other year in the Atlantic. Some very active years in the Atlantic like 1999 – the 15th most active on record going back 171 years – saw both a big gap in storms early in the season (47 days between Tropical Depression Two on July 3rd and the Depression that became Category 4 Hurricane Bret) and no storm formations for the first half of August. 1999, like 2022, was a La Niña year.

So the three named storms thus far is par for the course up until now.

The lesson for now is that it is way too soon to count on this being a sleepy season.

Using averages the 3rd named storm is assigned today August 2nd and the 4th storm named August 14th, but Colin was back at the start of July. So nothing remarkable has happened this season thus far.

The current quiet period is typical The quiet place, for now

About 90 percent of hurricanes form after August 1st and about 75 percent of hurricanes form after August 20th.

Season ramps up starting late August

This is an average and seasons can ramp up sooner or later than this, with some seasons having multiple peaks. But if we want to assign a time period when tropical cyclones begin to pop it would be around or after August 14-20th with acceleration peaking around August 28th. (ACE= accumulated cyclone energy)

Seasons speed up slow down speed up... we can calculate exactly how quickly the speed of the hurricane season typically accelerates or decelerates through something meteorologist Michael Lowry calls ACE acceleration. It resembles a seismograph or a hospital EKG strip. The ACE acceleration gets us to the answer we’re seeking for when hurricane season activity picks up. On average, the big ramp up to the most active part of the season happens the last week of August, centered around August 28th.

Many have blamed the Saharan dust (SAL) for the quiet tropical season thus far. But forecaster Lowry points out that before Dorian formed at the end of August in 2019, the tropical Atlantic was off to one of its least active starts in 20 years... despite record LOW dust cover in July and August. On the other hand, by the end of August 2005, the Atlantic already recorded one Category 4 and two Category 5 hurricanes, even though dust cover was running ABOVE average.

So while a dusty Atlantic/Caribbean may be playing some role, it’s likely just one of many factors such as unfavorable wind shear and an unfavorable MJO (rising and sinking air) and the pattern of warm and cold pockets of sea-surface water that have worked together to kept a lid on the season so far.

About 70% of Category 3 or higher hurricanes occur between August 20th and October 10th.

For more frequent weather info follow me on Twitter @MellishMeterWSB.