Eric Horst was 8 years old during Hurricane Agnes in 1972, and watching that storm of a lifetime is what inspired him to become a meteorologist.

So what's the difference between Agnes and the severe flooding caused by the remnants of Tropical Storm Lee?

There are a couple of factors involved, Horst said.

Agnes dumped 10-20 inches of rain over the eastern two-thirds of Pennsylvania, which feeds the Susquehanna River, while last week's rainfall was very heavy in some places and lighter in others, he said.

For example, portions of Lancaster, Lebanon and Dauphin counties "were crushed with rain," yet Reading only got 5 inches or so, said Horst, the director of Millersville University's Weather Information Center.

That's why the Susquehanna didn't crest as high as expected in Marietta, he said.

Forecasters were projecting significant rainfall over a broader area, so they were predicting more water would be fed into the river through creeks and streams, Horst said.

The Susquehanna crested just above 58 feet in Marietta, more than 4 feet less than previously anticipated and more than 6 feet below the peak during Hurricane Agnes.

Six more feet of water is almost the height of one floor in a house, he said, and would flood a larger area.

"The difference is significant," Horst said.

Though the flooding in Lancaster County was devastating for a number of people, "we're lucky" it didn't turn out to be worse, he said.

Something that also distinguishes Agnes from last week's four-day rainfall is that the 1972 hurricane was a 2 1/2-day "deluge," Horst said.

"We had a lot more water, and it came down a lot faster," he said.

What the county just experienced is the kind of flood that comes every two decades, Horst said.

Hurricane Agnes, however, was a once-a-century phenomenon that was "head and shoulders above this."