found this on tgr. those weather threads are the only useful thing on there....
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif
The last few weeks, since the snow stopped, a positive phase Arctic Oscillation occurred that is approximate to the record for the last 60 observed years. The polar vortex, the pool of low pressure atop the globe, has literally sucked the northern storm track away from the lower 48. For the central rockies, potent low pressure in the polar vortex trumps typical La Nina jet stream patterns and turns our wet pinapple express into a dry alberta clipper that steers around us. We need the storm track to migrate south and displace the blocking ridge established in the east pacific. Unfortunate us, this trend does not yet show signs of significant weakening and the current prediction from NOAA is that the AO positive signal will reamplify back to near record levels over the next two weeks before returning to neutral or negative trend. If this forecast is correct, we can expect the current high and dry to continue into January because there is usually a 1-2 week lag from signal change to results in the lower 48. We'll get some modest snowfall here and there but the probability for a big multi-day system to fill things in is low until the AO flips negative and holds there for a week. Prolonged snowy weather in the mid-latitudes of north america correlates strongly with negative AO phase. If you got holiday plans for the Tetons (central rockies, in general), you might want to reconsider or, at least, leave your new skis/boards at home. Sure hope this is wrong, but it is hard to ignore the effects of such an anomalous factor like an AO positive phase 60 year event.
