If I hear one more person say "So much for that 'global warming?'" I will scream. Here's a pretty good, readable explanation for why its so damn cold in the east (and so damn warm in the west).
...the Arctic is warming much faster than elsewhere. That Arctic/mid-latitude temperature difference, consequently, is getting smaller. And the smaller differential in temperatures is causing the west-to-east winds in the jet to weaken.
Strong jets tend to blow straight west to east; weaker jets tend to wander more in a drunken north/south path, increasing the likelihood of wavy patterns like the one we’ve seen almost non-stop since last winter.
When the jet stream’s waves grow larger, they tend to move eastward more slowly, which means the weather they generate also moves more slowly, creating more persistent weather patterns.
If you want a denser scientific explanation, just google "quasi resonant Rossby waves."