Storms are forecast heading to the Valley on Tuesday and into Wednesday.  

Meteorologist Andrew Deemer with the National Weather Service Phoenix Office says the leading concern is possible flooding or flash floods.

“Even if a lot of this stuff occurs overnight, it still can be impactful and you know at least with initial thunderstorms, thinking of the typical threats: Strong winds, lightning, and of course locally heavy rain," Deemer said. 

Deemer says the storms will potentially begin at 8 p.m. and pick up toward 10 p.m. and midnight. And then Wednesday morning a second wave of more widespread showers and thunderstorms is predicted anytime between 5 a.m. and 8 a.m.