Post Snowstorm Ice: The Winter Scourge of Western Washington

Transplants to our region from the central and eastern U.S. often laugh at the trepidation Northwesterners have for even a minor snowstorm.   We are told that in Michigan, Massachusetts, or XXX (fill in the blank), they LAUGH at a few inches of snow. Business stay open. Schools are never cancelled , etc.  And then the new Northwest resident smirks at the strong reaction of Puget Sound residents to even a few inches.  Sometimes even mocking.

Well, they simply don't understand.  In Michigan or whatever, the snow is generally powdery and dry.  Easily plowed.  And there rarely is much ice.

Not so in our area.  Ice is a huge threat and if local Department of Transportation don't pounce on roadway snow quickly, plowing and deicing aggressively, an ice layer will form that is not only difficult to remove, but a huge impediment to travel.

Ice that has destroyed the political careers of local politicians, like erstwhile Seattle Mayor Nickels.

The reason we have Godzilla-ice is easy to understand.  We live in a mild climate and the road temperatures are generally above freezing.    Then we get a rare snow event.  Snow falls on warm roadway and starts to melt into a slushy mess.  Many of our snow events include wet snow.  Then cold air pushes in from the Northwest through the Fraser River Valley gap and temperatures plummet--causing the ice to freeze into a coat that is treacherous and difficult to remove.

And then there are the hills, which make icy conditions even more dangerous and problematic.  It doesn't take a lot of snow to make things slippery and icy...a few inches of snow is enough.

Now experienced local departments of transportation know how to handle this situation.  First, they need to be on top of the forecasts and be ready to act.

Second, before a snow/cold event it is very useful to pre-treat the roadways with some kind of deicing or anti-icing solution-- or even road salt-- that decreases the freezing point and prevents any ice from bonding to the roadway.

Third, as soon as snow starts, plow the snow off aggressively and apply a second coat of deicer. 

Walking on a side road this AM, the development of the ice layer was obvious.

Just as obvious was the difference between a treated roadway and one left alone.

Were local transportation agencies aggressive enough for this event?  I will let others decide. 

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Finally, there have been a lot of comments about the European Center having a much better forecast than the U.S. GFS model for this event.  The truth is that the European Center also underplayed the situation.  For example here is the accumulated snow forecast for the event made last night (initialized at 4 PM Sunday).  A bit over 2 inches in Seattle....way too low and similar to the US model runs.

Now back to my nice cup of tea...

from Cliff Mass Weather and Climate Blog http://bit.ly/2S9kavy