NWS says Kentucky tornado cut 95-mile trench

(CNN) -- At least 45 separate tornadoes have been identified in last week's deadly outbreak across the Midwest and South, including one that stayed on the ground for 95 miles, tearing a swath through Kentucky and West Virginia, according to the National Weather Service.

The 45 confirmed twisters were among 144 reports of tornadoes, which may include multiple reports of the same tornado, in Friday's outbreak that left 40 people dead from Indiana to Georgia.

The tornado that struck the small town of West Liberty, Kentucky, had winds of 140 mph and was rated an EF-3, the National Weather Service said Monday. It stuck to the earth for 95 miles -- 60 miles in Kentucky and 35 miles into West Virginia.

The unusually severe storm system affected millions of people in 10 states, officials said. By the time it had calmed on Saturday, 40 were dead: 22 in Kentucky, 13 in Indiana, three in Ohio, and one each in Alabama and Georgia.

The strongest tornado appears to the the twister that hit Henryville, Indiana, which was rated an EF-4 with maximum winds at 175 mph. That tornado stayed on the ground for 49 miles across Washington, Scott, Clark and Jefferson counties in Indiana and Trimble County in Kentucky.

Another long-track tornado passed through Salyersville, Kentucky, just 20 miles south of hard-hit West Liberty. This tornado was given a rating of EF-3 with maximum winds estimated at 160 mph. This tornado was also on the ground for 49 miles, with a 48 mile track through Kentucky and an additional mile into West Virginia.

Less than 1% of the tornadoes that form each year reach EF-4 or EF-5 intensity, and few are on the ground for more than a few miles. But the dynamically charged nature of last Friday's atmosphere created an ideal environment for producing long-track, devastating tornadoes.

The National Weather Service uses the Enhanced Fujita scale to measure the intensity of tornadoes and the likely damage they will cause.

The tornado with the longest recorded path in U.S. history was the Tri-state tornado of 1925, which was rated an F-5 on the Fujita scale -- the previous model for tornado intensity -- and was on the ground for 219 miles over a three-and-a-half hour period. That twister still stands as the single deadliest tornado, responsible for 695 deaths across three states.

The Joplin, Missouri, tornado on May 22, 2011, was the deadliest tornado the United States has seen in the last 60 years, with 161 dead.