Remains of Allison fuel floods in Pennsylvania

Rescue workers use a raft to navigate flooded streets in Pennsylvania on Sunday

HORSHAM, Pennsylvania (CNN) -- The remnants of Tropical Storm Allison marched steadily northward on Sunday, leaving a trail of deep water and threats of more flooding in suburban Philadelphia.

The storm, which last week was drowning Houston in torrential rains, joined forces with a cold front from the west as it reached eastern Pennsylvania.

Bill Goodman, a National Weather Service meteorologist in Mount Holly, New Jersey, said the combined storms dumped nine inches of water along the Bucks-Montgomery County line north of Philadelphia. Half of that water, Goodman said, came in the hour or two before 8 p.m.

"When it falls that fast, you're going to have flooding," he told the Bucks County Courier Times.

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Carl Babinski, a meteorologist with AccuWeather, said the area could see between 10 and 14 inches of rainfall Sunday morning.

"This is the single biggest rainfall event that we've seen around here since Hurricane Floyd," Babinski told the Bucks County newspaper.

Floyd rammed ashore in North Carolina in September 1999. The massive storm swept up the east coast with its torrential rains and devastating floods, killing 56 people and causing an estimated $3 to 6 billion in damage.

Saturday's flooding forced the evacuation of at least two apartment complexes in Montgomery County and closed a segment of the Pennsylvania Turnpike (Interstate 276) between Willow Grove and Norristown.

Jim Kelly, the county's director of emergency preparedness, said that about 350 people were evacuated from the Village Green apartments in Upper Moreland Township when flood waters kept firefighters away from a blaze that destroyed one building and badly damaged two others.

Another 30 to 40 residents were evacuated from another complex because of the flooding, Kelly said.

Terry Williamson, director of communications for PECO Energy in Philadelphia, said that at least 55,000 customers were without power overnight in Bucks and Montgomery counties, along with Delaware and Chester counties to the south and east of Philadelphia.

By early Sunday morning, 4,000 of those customers were still waiting for power to be restored. Flooded streets impeded the progress of some of the rescue workers, Williamson said, but PECO expected to have power fully restored by noon.