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Isaias is the latest sign of an active hurricane season, but the peak is probably still one month away

Isaias is the latest sign of an active hurricane season, but the peak is probably still one month away

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Richmond Times-Dispatch{/byline}

As we wait to see how Hurricane Isaias develops before it takes a swing at the Eastern Seaboard next week, let’s step back and make sense of this busy 2020 season.

It’s certainly unusual that we recorded the Atlantic’s ninth named storm and second hurricane before the close of July.

By the count of named storms, the 2020 season has gone at faster pace than any other season up to this point.

According to the National Hurricane Center’s analysis of how an average season behaves, the ninth storm (with an “I” name) would be expected in the Atlantic by Oct. 4, and the second hurricane by Aug. 28.

As for hurricane pace, we only have to go back to 2018 to find the last time two hurricanes formed prior to Aug. 1. But in July of 2018, neither Beryl nor Chris struck land as a hurricane. Other recent seasons that had two early hurricanes wound up being above normal overall: 2008, 2005, 2003 and 1996. Only one, 1997, fell quiet after a busy start.

But those year-to-year comparisons about early activity don’t tell us as much about the trajectory of the storms that will follow. The bulk of major hurricane activity happens between late August and early October.

This year is on its way to achieving the forecast ranges of 13 to 19 named storms, six to 10 hurricanes and three to six major hurricanes. The National Oceanic and Atmospheric Administration plans to update that seasonal prediction in the coming weeks.

What accounts for 2020’s relative frenzy so far, and the ominous forecast?

It’s a combination of things being broadly favorable across the ocean this season, and specifically favorable around each system so far. The list of factors includes: generally warmer ocean temperatures, a neutral phase of the El Niño-La Niña cycle, less wind shear to rip storms apart, less dry air to choke developing thunderstorms off, and fronts that stalled out in the right places and times to spawn some of those tropical lows.

Those ingredients inform the seasonal forecasts, to the extent that they can be predicted. Studies show that climate change has a role in how hurricanes behave and the kind of damage they can do, but there isn’t evidence that it’s boosting their overall numbers. Even in a warming world, some years will be relatively quiet in the Atlantic due to short-term fluctuations in those factors listed above.

And it always bears repeating: The raw storm count doesn’t say much about what kind of impact they’ll have on people.

So far, five of the nine storms came ashore in the U.S. or had a significant brush with the mainland, and another three affected islands elsewhere around the Caribbean and Atlantic. Only Dolly remained entirely clear of land. This season’s other hurricane — Hanna — made landfall in South Texas last week.

A season can also be tracked and compared by the amount of energy those storms release. By that way of looking at it, a year with one or two long-lived major hurricanes could be considered more active than a year with a dozen short-lived tropical storms.

And many of the storms that propelled us along the alphabet so far in 2020 fell into the latter column.

According to analysis by Colorado State University meteorologists, the 2020 season-to-date energy release is more typical of where we’d be by the third week of August. So by that measure we’re ahead of normal now, but not as far ahead as the naming list alone suggests.

By this point in 2005, there had been three hurricanes including powerful Category 4 Dennis and Category 5 Emily.

While it remains to be seen what kind of effects Isaias will have on our nearby coastline, the letter “I” has seen more turnover and retirement due to damaging effects than any other letter.

The often-infamous “I” storms are usually unleashed in late August and September, when the seasonal activity peaks and the ingredients are at their most potent.

Just in this century, that retired roster includes Iris, Isidore, Isabel, Ivan, Ike, Igor, Irene, Ingrid and Irma.

Two other systems — a tropical depression that formed off the western coast of Africa on Friday and another disturbance in the central Atlantic — have modest chances of developing into our “J” and “K” storms in the coming days according to the NHC, but remote chances of affecting us.

The 2020 list continues with:

Josephine, Kyle, Laura, Marco, Nana, Omar, Paulette, Rene, Sally, Teddy, Vicky and Wilfred.

For comparison, the earliest-forming “J” was Jose on Aug. 22, 2005, and the earliest “K” was catastrophic Katrina on Aug. 24 of that same year. Barring a major pause, this year has time to extend its run of early formation records. But with any luck, it will not resemble disastrous 2005 in any other way.

Check for an update tomorrow on how Monday’s forecast is shaping up for Virginia and North Carolina, and more updates in print and online when Isaias nears the area next week.

Check Richmond.com/weather for John Boyer’s forecast updates. Contact him at JBoyer@timesdispatch.com.

Check Richmond.com/weather for John Boyer’s forecast updates. Contact him at JBoyer@timesdispatch.com.

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