The aircraft soundings over Sea Tac Airport shows that profound warming and strong southerly/southwesterly winds moving in aloft (time increases to the left, height is in pressure, 850 is about 5000 ft)
Right now strong easterly flow is maintaining cool air in the passes, where it is still snowing (hard). This is wet dense snow. The latest model runs suggest that the warm air air wins out and the precipitation will turn to rain in the passes during the afternoon. With heavy snow on the mountains, with a good chance of rain on top of it, the avalanche threat is serious. The passes are now closed and the NW Avalanche Center is showing high avalanche danger in the mountains.