Sign up for one of our email newsletters. The National Weather Service has issued a flood watch for several counties in the Pittsburgh area. The watch is in effect until 3 a.m. Sunday. Roads could flood and creeks and streams could overflow their banks, according to the watch. Counties covered by the watch include Allegheny, Armstrong, Butler and Westmoreland counties. The watch is in effect ahead of a cold front. Up to 2.5 inches of total rainfall, with isolated higher totals, is expected.