New York City - How bad are WX delays at EWR tonight?

Was planning on switching my flight for tomorrow to tonight EWR-LHR, but curious if i risk just a WX Delay/Cancellation it might not be worth the hassle

The present FAA delay report for EWR (http://www.fly.faa.gov/flyfaa/flyfaaindex.jsp?ARPT=EWR&p=0) and the evening weather.com report (http://www.weather.com/weather/hourbyhour/graph/Newark+Liberty+International+Airport+NJ+EWR:9)

As it does now (10% chance of precip through the evening hours), Weather.com has shown low probability of rain all day, and there's been a thunderstorm every hour or two popping up, so it seems like a situation very difficult to forecast with accuracy.