Weather Authority: Severe Thunderstorm Watch issued ahead of powerful evening storms FOX 29's Scott Williams has your weekend forecast. PHILADELPHIA - The National Weather Service has issued severe thunderstorm watches and warnings as a band of strong storms move across the Delaware Valley Saturday evening. The area-wide Severe Thunderstorm Watch will be in effect until 11 p.m., according to the weather service. Forecasters warn of strong wind gusts up to 70 MPH and possible bouts of hail to accompany rain, thunder and lightning. The first cluster of storms triggered brief Severe Thunderstorm Warnings in parts of the region on Saturday afternoon, including Philadelphia and parts of New Jersey. Forecasters anticipate the severe weather warnings will become more widespread and continue off-and-on throughout the night.