I remember these well! before I knew to look at the 500mb stuff (and just stared at surface pressure and precip depictions) these were insanely frustrating. precip would build near the gulf with a low approaching from what appears to be the right angle. then the precip would suddenly disappear at the mountains, leaving DC high and dry....before it EXPLODED back onto the scene when the low bombed off the NJ coast. to a snow weenie with no clue why precip goes where it goes, this is one of the most painful events to witness. please be kind to surface map watchers.