The National Weather Service has issued a tornado watch for Northampton and Lehigh counties until 2 a.m. Saturday. A flash flood watch is also in effect until 8 a.m. Saturday.
There is a potential for strong to severe thunderstorms as a cold front enters the region, the NWS says in a special weather statement.
Any stronger thunderstorm could be capable of producing locally damaging winds and hail. In addition, heavy rain could cause localized, but brief, flooding.
Rainfall amounts could total one to one and a half inches. Greater amounts -- up to two and a half inches -- is possible with the stronger storms.
At this time, the greater chance for a severe thunderstorm appears to be across Delaware and Maryland -- and possibly southeastern Pennsylvania.