With a blustery storm already blowing in, the National Weather Service has issued a ‘special weather statement’ for western Washington that includes — WA Niña style — “a risk of snow.”

COLD AIR IS EXPECTED TO DEVELOP OVER WESTERN CANADA DURING THE UPCOMING WEEK. THERE ARE STRONG INDICATIONS THAT CHANGES IN THE WIND FLOW ALOFT TOWARD THE END OF THE WEEK WILL ALLOW SOME OF THIS COLDER AIR OVER WESTERN CANADA TO FILTER INTO WESTERN WASHINGTON FRIDAY OR SATURDAY.

WEATHER GUIDANCE ALSO SUGGESTS THAT THERE IS A RISK OF SNOW…OR MIXED RAIN AND SNOW SHOWERS OVER PORTIONS OF THE AREA FRIDAY OR SATURDAY. THE HIGHEST RISK WILL BE WHERE THE AIR IS COLDER…OVER THE NORTH INTERIOR.

WHILE WEATHER GUIDANCE HAS BEEN CONSISTENT IN SHOWING A CHANGE TO A COLDER WEATHER PATTERN…THEY HAVE BEEN UNEVEN IN SHOWING HOW COLD IT WILL GET AND HOW MUCH…IF ANY…SNOW WILL FALL.

We’ve already posted about Metro’s plans for what is expected to be a colder and possibly more snowy winter than usual around Seattle. Here’s the summary of online tools to help you catch your bus:

• Sign up to receive Transit Alerts for the routes you use most often;
(www.kingcounty.gov/metro/signup)

• Check the print and online timetables for snow route maps;
(www.kingcounty.gov/metro)

• If the weather is bad, check the color-coded status map on Metro Online before you travel;
(www.kingcounty.gov/metro/snow)

SDOT is also facing winter 2010/2011 with a fresh plan including a tiered plan to clear Seattle streets of snow. In SDOT’s maps, you can check out your area to see what will be plowed and what won’t. SDOT snow service tiers are below.

SDOT explanation for route selection:

Routes were selected using criteria that include the busiest streets that connect our neighborhoods with downtown or within the greater Puget Sound region; streets used by the transit agencies even in harsh weather; streets used most frequently by public safety agencies; and streets deemed important to public institutions such as schools, universities and hospitals, and also Seattle’s major employers.

University of Washington meteorologist Cliff Mass says SDOT should focus its snow removal on fewer, more critical streets. We’re with Mass. We’d gladly trade a few blues and greens away so that Madison and more of 23rd could go orange.

Now the city has 30 plows. Lets say that 25 are available at any one time (which would be very good I would think). And lets assume that they plow at 20 mph. So they could cover at best roughly 500 miles of roadway an hour. How many miles of roadway lanes are included in the routes outlined in the map…my rough estimate is 1200 lane miles. So it would take 2.5 hours to cover the city–and that is optimistic. If the snowfall is relatively light (.5-1 inch an hour) this might be ok, but if the snow is heavy (several inches per hour) there is going to be trouble. My suggestion: have a smaller core set of major streets that get priority in heavy snow. Get those clear, keep them clear, and steer the buses to those streets.