More Snow Forecast

I know have been bringing hope as of late and then quickly taking it away...but what would be a Northwest Winter without disappointment? Well we have another snow situation setting up. This is looking much more like the classical pattern of snow here. The pattern is set up with a high amplitude ridge over the Eastern part of the pacific. Typically we want that ridge to really extend up to Alaska and beyond up towards the pole. We then need a shortwave system on the longwave pattern to move down from BC, come out over the water, and then move into SW Washington or NW Oregon. This does two things: one the system being so close will "pull" cold continental air from BC that will almost be hindered by a barrier. Well that barrier will cease to control the air with the system drawing that air out so the Northwest will be blanketed by some very cold air. Two: The closeness of the system spins the moisture up from the south and boom, snow. Here is a picture of that kind of situation. 

And guess what? That is the forecast picture for Wed/Thur. You don't need to know what exactly all the data is in this pictures, but just associate the Red with clouds and moisture. You can see the ridge, high amplitude over Alaska and above. And that low pressure system sitting right over us. Now this forecast can change over the next few days but this looks promising. Here is a picture of the surface. 

The surface map shows a surface low just offshore and do you see those black lines into BC that are all bunched up together? That is what the business calls an arctic front. Lots of cold air (the pink purple in Canada) is seperated from us mainly by the Rocky mountains and a low like this will draw that air out of the mountain gaps, pouring into the Northwest. Here is a map just a few hours later

The low has moved more south and that cooler air (even the light blue, turquoise, is very VERY cold) has begun really pouring over us. There may not be much moisture around at this point but this would spell a very cold streak. But lets not forget about the snow :)

This is a map for 24hr snowfall ending Wednesday afternoon...The snow certainly will be felt all around Western Washington. The models don't do a great job predicting snowfall amounts but what you can take from this is it will be affecting EVERYONE (maybe not some areas affected by a "snow" shadow, i'll talk about that in a future blog). Here is a later map. 

That is potentially 1-3 inches around the lowlands and higher amounts towards the foothills. This could get very interesting over the next few days when models start to really narrow down on what might happen.