Generally, an El Nino strengthens the southern stream of the jet stream and weakens the northern. The southern stream is generally what brings our coastal storms, so yes, we are more likely to get the big storms. With the lack of a northern stream, though, there'll be a lack of arctic air, and thus more rain/less snow. The south and east coast tend to be wetter, and cooler due to the cloud cover. The truly arctic shots that the northern stream brings are generally absent, though (no Alberta clippers, for instance). Due to that, the Midwest tends to be much warmer. PA's temperatures can vary as we are at the intersection of the warmer than normal Midwest air and cooler than normal southern/coastal air. Whether PA gets slightly warmer or cooler temps overall is unknown and may depend on which end of the state your talking, but either way we'll get less clipper type storms, more coastals, and those coastals will be more cold rain than snow. We're less likely to see those super cold 10 degree shots.
As another highpoint, the California drought will get a serious respite as those southern stream storms slam into California, drenching the lower elevations and leading to very high snow pack in the Sierra's. They'll be complaining about mudslides instead.
FWIW, there was some question over how the El Nino would interact with "the blob", which was an area of warmer than typical sea surface temperatures off Oregon/Washington/British Columbia for the last few years. That blob is what bent the northern stream and led to our last 2 colder than average winters in the Midwest and eastern US, as well as caused the California drought. The blob is separate from el nino/la nina, it was a separate phenomenon. It's largely been answered, though. The El Nino won. It forced storms into that area and "the blob" is pretty much gone.
So the remaining question is when the El Nino peaks. Some think it'll peak early, and a weakening el nino in late winter could lead to some wild swings in late winter/early spring weather. February 2010 was such a scenario.
