If you have been paying attention to the news recently, you are aware that meteorologists are forecasting a La Nina winter.  The local news media would have us thinking that we may be house bound all winter in Seattle with snowdrifts blocking our second story windows.  "Snowmageddon" is approaching!  Indeed, there is a strong La Nina ocean current developing in the Pacific Ocean.  But what does this really mean for those us who like to play in the snow ...and in avalanche terrain? 

A recent article written by our very own Mark Moore and Rich Marriot provides a thorough explanation of La Nina and its effect on winter weather in the western US.  We will post the article on the website once it is final, but until then, take home these points...

• A La Nina ocean current is developing, which means colder water in the Pacific off the west coast of the US.

• There is in fact a strong correlation between the La Nina ocean current and the weather in the PNW...which isn't the case with El Nino.

• While the reason why is not entirely clear, the La Nina ocean current results in the jet stream following one of two paths; across the northern Pacific roughly at the latitude of the PNW, or if a blocking high pressure develops off the coast, more to the north through Alaska and Canada.   The first of these paths results in copious precipitation, but the more northerly path leads to cold, dry weather.  We are likely to see some of both.

• The fluctuation between these two jet stream paths can wreak havoc on the snowpack.  Periods of cold, dry weather followed by large amounts of precipitation can result in heavy loading on top of ice crusts and surface hoar layers, not a good combination.

The summary...it should be a good winter, but we will have some cold, dry spells, and the snowpack could get a bit sketchy as a result.  Brush up your avalanche skills...and be careful.