Thursday, November 18, 2010
Bellingham Fun, Fraser Outflow and an Admission
Cold, dry modified arctic air is now pushing through the Fraser River Valley into Bellingham and areas to the north.
Here are the latest observations at the Bellingham Airport. Look at the wind direction. It shifted from southeasterly (90 is E, 180 is S, etc) to northerly and then northeasterly (20-30)---air coming right out of the Fraser! As the wind direction shifted the temperature began to drop rapidly (now 35F) and the dewpoint dropped to 31F (which means the air is getting drier). Lower humidities HELP snow, since it facilitates evaporation and thus cooling.
Bottom line--it is probably now cold enough for snow in Bellingham...and that NE flow is going to strengthen and push over the San Juans and then to Vancouver Island and then head down to the Olympics. And these folks are probably going to see some light snow before this is all over. And yes, some strong winds for Bellingham and the San Juans. Believe me...it will get fiercely windy at the top of Mt. Constitution on Orcas before this over. And I expect Jim Forman and the rest of the TV folks to be stationed at Bellis Fair Mall in N. Bellinghan as they always do...with the flags waving in the background.
Below is the 24-h snowfall ending 4 PM on Saturday. Snow from north Bellingham across the north San Juans..and then southern Vancouver Is. And the northern part of the Olympic Peninsula just back from the water.
There is another focus of snow...SE of the Olympics around the Hood Canal...their snow will be from SE flow that will ascend those Olympics slopes. Heavy precip pushes the freezing level down...bringing snow with it. Otherwise...no snow on Saturday for the lowlands--but some light snow in the mountains.
There really is very limited moisture with this event...and that is working against any significant snow. Most of the area will get nothing.
Finally, let me admit something...there are a lot of very nervous meteorologists in town. We look at the forecast pressures and temperatures for tomorrow at 1 PM (below) and see a low over SW WA and cold air over BC, ready to be sucked down towards the low. Cooler air is already moving into the Fraser Valley and out into Bellingham. This is close to a pattern that brings snow...but the models are emphatic that it is too warm over most of the lowlands for snow. The freezing level is at around 2000 ft and the snow level is around 1000 ft. This is close. If our models are wrong....well, you know what I am worried about. It won't be the first snow mistake we've made.
PS: Tuesday AM looks VERY COLD
Posted by Cliff Mass at 9:42 PM