Flurry of Eastern Pacific Storms Coming to an End

It has been a July for the record books in the eastern Pacific Ocean, as the basin tied records for both the most named storms and the most major hurricanes to form in that month. And all after no activity during the first few weeks of the season.

Over the last few days, Tropical Storm Darby dumped rain on Hawaii and Hurricane Georgette became a tiny powerhouse.

But as those storms wind down, the flurry of activity is tapering off; no new storms are expected for the remainder of the month.

Hurricane season in the eastern Pacific officially begins in mid-May, a couple weeks earlier than in the Atlantic. Whether any storms form, though, depends on prevailing conditions.

In the eastern Pacific, those conditions didn’t become conducive to storm formation until the beginning of July — then it was like Mother Nature flipped a switch. Storm after storm after storm formed and churned out to sea.

In all, seven storms formed and reached tropical storm strength, the point at which they receive a name. Those seven — Agatha, Blas, Celia, Darby, Estelle, Frank, and Georgette — tied the record for most storms to form in July, set in 1985.

Three of them — Blas, Celia, and Georgette — tied the record for most major hurricanes (those of Category 3 or higher) to form in the basin in July.

“This July has been especially impressive,” Blake said. “Only July of 1992 will likely end up with more ACE in the eastern pacific.” (ACE is a measure of a basin’s total hurricane energy over a season, taking into account the size, wind speed and longevity of each storm.)

All seven storms formed off the west coast of Mexico and Central America — a prime storm nursery — with all but one heading out to sea.

Tropical Storm Darby moved westward into the central Pacific and dumped intense rains on part of Hawaii. More than 11 inches fell on parts of Oahu, prompting flash flood warnings.

Meanwhile, Hurricane Georgette continues to churn far out at sea. While it is a small storm, with hurricane-force winds extending out only 20 miles and tropical storm-force only 90 miles, it reached Category 4 status at its peak. It has since weakened and will continue to do so.

As hurricanes traverse the ocean, they stir up the water, leaving a wake of cold water behind them. Georgette was able to ramp up despite this because, in part, it went over an area of slightly warmer waters. It also went through an area of very low wind shear, which tends to tear apart burgeoning storms.

“Georgette is quite small, and we have seen over and over these small cyclones can go quite quickly up (and down) given the right environment,” Blake said.

The only other storm still hanging on is Tropical Storm Frank, which will dissipate by the end of the week.

After that, there are no signs of areas that could spawn further storms for the next five days. This could be in part because of a climate signal that propagates around the world, with phases that enhance storm formation and suppress it. While the former was present in July, the latter seems to be setting up shop now.

How the rest of the season will play out is unclear. Before the season began, it was thought that a La Niña would follow the recent exceptionally strong El Niño. La Niña tends to tamp down storm activity in the eastern Pacific and enhance it in the Atlantic. But conditions now are neutral and computer models have backed off their La Niña predictions slightly.

So far, the Atlantic has been quiet because of a mass of dust and dry air flowing off of Africa. The busiest time of the season generally isn’t until August and September and the basin is forecast to have a near-normal season.

As the world warms, the most intense hurricanes are expected to become a bigger proportion of all hurricanes, even if the total number of those storms worldwide decreases slightly. How warming might impact particular basins is still an area of research, though there are suggestions that Hawaii might see more storms hit its islands as temperatures rise.