Folks...I don't want to cry wolf about this...but if you take the current model output literally, we will have a significant lowland snow event after midnight tonight. What gets me nervous is that my colleagues in the National Weather Service are not mentioning the possibility at all in their forecast or discussion.
Here is the 24-h snowfall map for the period ending 4PM Monday.
Wow. The mountains get 2-3 feet of snow and the Puget Sound and SW WA lowlands get several inches. There would be precipitation shadowing west and north of Seattle. I should also note that the Weather Channel automated system is also going for early morning snow.
The previous run has only scattered, light snow showers. Here it is. So we don't have run to run consistently...which tells us that there is real uncertainty here.
The temperatures are marginal for snow later this evening, but the last model run suggests that a heavy precipitation rate will drive the snow level down to sea level in many locations. This kind of situation is called a diabatic snow event...since the melting of snow is an important source of the cool (diabatic is term for such an effect). A tricky forecast since it depends on getting the intensity of the precipitation correct...something we are not that good at.
YES, there is uncertainty with this event. If the last run is wrong and the precipitation is lighter all the lowlands will get is rain. Anyway, just be aware of the possibility. If this happens the commute tomorrow will be a zoo. If tonight's run has it, I would be prepared.
Want more weather fun? The models have a major windstorm coming in on Wednesday. And there was snow today in Los Angeles and several inches around Tucson.