Philadelphia might experience sustained winds between 40 and 50 m.p.h. and gusts up to 60 m.p.h., which "could cause significant damage or downage to trees, power outages, and other infrastructure disruptions," Nutter said.
"This storm is coming," he said. "The only question is its severity. If you live in an area that is prone to flooding, prepare to evacuate as needed."
Peco Energy has placed extra personnel and crew on standby and was working to arrange for support from Commonwealth Edison in Chicago.
The city will provide another update Friday and possibly declare a severe weather emergency, depending on the storm track. Already, Philadelphia's rainfall this month has totaled 13.11 inches, surpassing the previous record for any month - 13.07 inches, set in September 2009.
The National Association of Insurance Commissioners, citing the hurricane, canceled its planned summer meeting of 1,500 members next week in Philadelphia.
The same caution and preparation were reported in the four suburban counties in Pennsylvania.
Delaware County's Emergency Operations Center will open late Saturday, and there will be additional staffing for the 911 center, said Chad Brooks, chief of operations for the Department of Emergency Services.
"The best thing is prevention," he said. He recalled the flash flooding that killed four people in Pittsburgh last week, and cautioned that people should not drive into low-lying or flooded areas.
In Bucks County, Neshaminy Creek is almost always the first to flood, spilling over in Northampton, Middletown, Bristol, and Bensalem Townships and several small boroughs along the way.
