Harvey, now a tropical storm, is expected to be a major hurricane when it slams into the Gulf Coast of Texas late Friday or early Saturday, according to the National Hurricane Center. (Image from NOAA)

(CNSNews.com) - Thursday, August 24, 2017 marks a record 142 straight months since the last major hurricane made landfall in the continental United States. But that record major-hurricane drought may be coming to an end.

According to the National Hurricane Center, Tropical Storm Harvey is "quickly strengthening" in the Gulf of Mexico and is forecast to be a major hurricane when it approaches the middle Texas coast on Friday night or Saturday morning.

The storm is then expected to stall, producing huge amounts of rain, in excess of 20 inches, according to some forecasts. "Life-threatening storm surge and freshwater flooding expected," says the advisory from the National Hurricane Center.

The National Hurricane Center shows the storm remaining in the Texas-Louisiana coastal area through Tuesday.

A major hurricane is Category 3 or higher, which mean sustained winds of 111 to 129 miles an hour (on the Saffir-Simpson Hurricane Wind Scale).

The latest track of Tropical Storm Harvey, expected to develop into a major hurricane on Friday. (Image from NOAA)

The last major hurricane to hit the continental United States was Hurricane Wilma, which struck Florida on Oct. 24, 2005. Prior to the current 142-month stretch without a major hurricane strike in the continental U.S., the longest period without a major hurricane making landfall was the 96 months between September 1860 and August 1869.

The National Hurricane Center says on average, 12 tropical storms, 6 of which become hurricanes, form over the Atlantic Ocean, Caribbean Sea, or Gulf of Mexico during the hurricane season, which runs from June 1 to November 30 each year. In the Central Pacific Ocean, an average of 3 tropical storms, 2 of which become hurricanes, form or move over the area during the hurricane season.

At the start of the current hurricane season, the National Oceanic and Atmospheric Administration predicted a 45 percent chance of an above-normal hurricane season; a 35 percent chance of a near-normal season; and only a 20 percent chance of a below-normal season.

Storms are named when they generate winds of 39 mph or higher.

Historically, the leading cause of hurricane-related deaths in the United States is storm surge, the rapid rise of water pushed ashore by the storm's winds. Storm surge can travel several miles inland, especially along bays, rivers, and estuaries.

Flooding from heavy rains is the second leading cause of fatalities tropical storms and hurricanes, followed by winds that can destroy buildings and send debris flying.

Hurricanes and tropical storms may also produce tornadoes and dangerous waves.