Storm activity during the 2019 Atlantic hurricane season could be slightly below normal according to researchers at Colorado State University, who cite an expected weak El Niño effect as a major factor.

Researchers predict that five storms will reach hurricane strength, with sustained winds above 74 mph, and two will intensify to major hurricane strength, with sustained winds topping 111 mph.

Overall tropical storm activity in the Atlantic basin is forecast to be about 75 percent of average, compared to 120 percent for 2018, when hurricanes Florence and Michael devastated parts of the Carolinas and the Florida panhandle.

Meteorologists at the CSU Tropical Meteorology Project are predicting 13 named storms for the season, which runs June 1 through Nov. 30.

The 2019 season is exhibiting characteristics similar to 1969, 1987, 1991, 2002 and 2009, said Phil Klotzbach, research scientist in CSU's Department of Atmospheric Science and lead author of the preliminary forecast.

The tropical Atlantic is slightly cooler than normal, providing less fuel for tropical cyclone formation and intensification, said Klotzbach.

Drier atmospheric conditions also could suppress storm activity essential to hurricane development. A weak El Niño in the tropical Pacific is expected to persist through the peak of the Atlantic hurricane season, which begins in late summer.

The CSU forecast predicts a 48 percent probability of landfall along the United States coastline, compared to a 52 percent probability over the last 100 years.

CSU meteorologists are expected to issue an update in June. National Oceanic and Atmospheric Administration meteorologists will issue their first 2019 hurricane forecast in late May.