With the end of hurricane season slightly more than a month away, it’s clear that the Central Pacific Region so far has had an unexpected slightly above-average season.

The tropical cyclone count in the Central Pacific was six as of Sunday, which surpasses the average of about four to five cyclones.

Before the season kicked off on June 1, National Weather Service meteorologists predicted there would be a 70 percent chance of the Central Pacific having a below-average season, a 25 percent chance of having a normal season and just a 5 percent chance of having an above-normal season.

The NWS, along with the Central Pacific Hurricane Center, predicted in May that the season would see only one to three tropical cyclones.

In 2010 there were no tropical cyclones that entered the Central Pacific, and 2011 and 2012 saw only one cycle each.

Weather service meteorologist Anthony Reynes said Sunday it appears unlikely that another system will affect the main Hawaiian Islands before the season ends Nov. 30, but cautioned that anything is possible.

Hurricane Iwa, for example, which struck in 1982, hit the isles in November.

"We still have to keep an eye on it," Reynes said.

The unexpected number of tropical cyclones that have hit the Central Pacific so far this year was in part due to upper-level wind patterns early in the season remaining more favorable than expected over the eastern parts of the region, Reynes said. Strong upper-level winds tend to break apart weather systems before they ever have a chance to have a major impact on the isles.

Weak wind shear, for example, helped keep Hurricane Flossie on course to hit Hawaii back in July.

"It took a little longer for those winds to become stronger," Reynes said.

In the midst of forecasting for Flossie — which wound up hitting Hawaii island as a tropical storm and decreased in strength as it tracked across the state — NWS warning coordination meteorologist Michael Cantin said scientists were still expecting the season to yield below-average numbers.

The past few years have seen low numbers of storms because an expected switch to an El Niño weather pattern from a La Niña weather pattern instead brought on neutral conditions that are expected to persist until at least next spring, Reynes said.

Both Iwa in 1982 and Iniki in 1992 struck during El Niño years, when sea surface temperatures in the eastern tropical Pacific are warmer than average and thus more favorable for storms.

Reynes noted that this year’s higher-than-expected number of cyclones so far can also be attributed to the Eastern Pacific having a particularly active hurricane season.

"It is more than we were expecting (for the Central Pacific), but also we have to keep in mind that at least two of those were from the eastern Pacific," he said. "They didn’t form in the Central Pacific."

Meanwhile, scientists have found new evidence that Pacific Ocean temperatures drive tornado activity on the mainland.

Surveying more than 56,000 tornadoes from 1950 to 2011, researchers from the University of Missouri found that higher-than-average ocean temperatures corresponded with a 20 percent increase in tornadoes in the Midwest’s so-called "Tornado Alley." When sea surface temperatures were lower, more tornadoes tracked from southern states into Tennessee, Illinois and Indiana.

"Differences in sea temperatures influence the route of the jet stream as it passes over the Pacific and, eventually, to the United States," said Laurel McCoy, an atmospheric graduate student at the university’s School of Natural Resources, in a statement Thursday. "Tornado-producing storms usually are triggered by, and will follow, the jet stream. This helps explain why we found a rise in the number of tornados and a change in their location when sea temperatures fluctuated."

By studying the relationship between tornadoes and long-term temperature trends called Pacific decadal oscillation, McCoy said weather forecasters will be better equipped to predict dangerous storms.

The research was presented last week at the National Weather Association conference in South Carolina.

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Star-Advertiser reporter Michael Tsai contributed to this report.