The storms will be mostly scattered, but could turn severe at times Tuesday night. Forecasters expect the final day of the six-day heat wave to include uncomfortable humidity that could lead to more severe storms. What we know:Mugginess will continue to build on Tuesday, leading to another round of scattered storms in the evening that could turn severe. What's next:The heat wave will finally break on Wednesday when temperatures fall out of the 90s for the first time in almost a week. Humidity will briefly return on Thursday, and dissipate by Friday, leading to a stellar weekend across the Philadelphia area.