The combination of an ever increasing hot and humid air mass and a strong upper level disturbance will cause a severe weather outbreak later today and tonight across much of the Ohio Valley, Mid-Atlantic and Northeast US. Impressive storms are now rapidly firing up across northeastern Ohio and northwestern Pennsylvania and are advancing eastward at a pretty good clip (~50 mph). These storms are capable of spawning damaging wind gusts, large hail and even tornadoes later today from central and northern Pennsylvania across southern New York into southern New England. As far as the I-95 corridor is concerned from DC to Philly to NYC, while the greatest threat for severe weather exists in upstate Pennsylvania and interior southern New York, strong-to-severe storms are certainly capable of reaching the New York City and Philly metro regions at the end of the day or early tonight, and perhaps even as far south and east as the area from DC to South Jersey. Stay tuned.