At a Glance

There are six named storms currently active in the Eastern Pacific and Atlantic basins.This appeared to tie a record number of active storms at once in the two basins combined.Four of these tropical cyclones developed on Tuesday alone.September is the peak month in the Atlantic Basin, and is typically very active in the Eastern Pacific.The Atlantic Basin is expected to remain active through the end of the month, perhaps into early October.

Six named storms are currently active in the Atlantic and Eastern Pacific basins, which appears to have tied a record number of combined storms at once in those two areas.

While and were spinning in the Atlantic and Eastern Pacific, : and in the Atlantic Basin, and and in the Eastern Pacific Basin.

After checking with colleagues, veteran National Hurricane Center forecaster Eric Blake tweeted that this combined number of active storms in both basins was believed to tie a modern record from .

"They are forming ," Blake tweeted Tuesday afternoon.

Three of those Tuesday newcomers formed at roughly the same time – around 11 a.m. EDT. About two hours later, the NHC initiated advisories on near the upper Texas coast. Ninety minutes after that, it as Tropical Storm Imelda.

This made for a very busy Tuesday at the NHC.

As Neal Dorst of NOAA's Hurricane Research Division pointed out, not only in the Atlantic Basin, but is also part of a broad peak of activity in the Eastern Pacific.

In September, ocean temperatures are nearly at their yearly peak, and shearing winds that can rip apart tropical storms and hurricanes are typically at their lowest.

There are two other factors contributing to this active period.

One is a large-scale wave in the atmosphere known as a convectively coupled Kelvin wave (CCKW), which has already tipped the Atlantic Basin into a favorable state for tropical development, as by Michael Ventrice at The Weather Company, an Business.

"This is the very same Kelvin wave that passed the Atlantic Basin back in the third week of August, aiding in the genesis of Hurricane Dorian," Ventrice told weather.com.

Ventrice said these stronger Kelvin waves can circle the globe multiple times.

"It's stronger passing the Pacific than it was back in the front half of August."

Another large-scale atmospheric disturbance known as the (MJO) is moving into a favorable configuration to give a boost to tropical development in the Atlantic Basin, and is forecast to remain in that favorable state into early October.

In the Caribbean and Gulf of Mexico, hurricanes are four times more likely when the MJO is in a favorable phase compared to when it is unfavorable, .

According to the , there have been as many as five active Atlantic tropical cyclones at once, which occurred Sept. 10-12, 1971. No more than two of those were hurricane strength at any one time.

Four simultaneous Atlantic hurricanes were documented both on Aug. 22, 1893, and Sept. 26-27, 1998.

Infrared satellite image of four hurricanes at once in the Atlantic Basin on Sept. 26, 1998.

(Credit: NOAA)

On Aug. 26, 1974, there were five simultaneous named storms of at least tropical storm strength in the Eastern Pacific Basin east of the international date line, Phil Klotzbach, a tropical scientist at Colorado State University, told weather.com in 2015.

Five active tropical cyclones were active in the eastern Pacific Ocean at 5 a.m. PDT on Aug. 26, 1974.

(Data: Phil Klotzbach, NHC)

Klotzbach said in a tweet that this was the first time there were three named storms with winds of at least 60 mph simultaneously in the Eastern Pacific Basin in .