[Article by Robert Nelson of Snoqualmie Valley weather]
UPDATE | FEBRUARY 11th, 10PM: The Winter Storm warning for the Snoqualmie Valley continues through February 12th at 6AM. The National Weather Service said another 3-9 inches of snow is possible for our area through Tuesday morning. I-90 remains closed over Snoqualmie Pass from exit 34 in North Bend to exit 106 in Ellensburg. Road conditions will be re-evaluated at midnight. SR 18 over Tiger Mt. was closed for the past two hours due to crashes and disabled vehicles, which were cleared when a tree came down across the roadway around 10PM. Driving conditions are poor throughout the Valley. Snoqualmie Valley Schools are closed again on February 12th. The heavy, wet snow is causing power outages and downed trees/limbs across the Puget Sound region.
UPDATE | FEBRUARY 11TH, 7:45AM: After roughly 5-6 inches of snow coated the Valley overnight, the Winter Storm Watch was upgraded to a Storm Warning for the East Puget Sound lowlands. Areas west of the Snoqualmie Valley may see less snow now as warm air comes in with Monday’s storm… giving the potential for a slushy mess, BUT the National Weather Service said it should be all snow in the Cascade Foothills with the possibility of 8-12 inches in the Snoqualmie Valley.
UPDATE | FEBRUARY 10th, 6PM: Sunday night 1-4″ of snow is possible, starting around 5pm or so. Monday afternoon the next system quickly moves in, but it is now forecast to come in farther north than earlier weather models, spreading warmer air into Seattle and areas south. Seattle and south should see heavy snow, but will likely bounce around from snow to freezing rain, to rain and possibly back to snow as it gets darker. The Snoqualmie alley could see 8-12″ of snow with this system, BUT a lot is dependent on the storm track. If the track happens to be slightly farther south, it’ll remain snow for Seattle and definitely for us in the foothills. People really shouldn’t be hitting the roads tomorrow, if they do they should be home before the afternoon.
At 6PM, the Snoqualmie Valley School District announced that schools would be closed Monday, February, 11th. All activities are cancelled and the District Office is closed to the public. The district said “given the winter weather advisories this week, we will continue to closely monitor conditions and provide updates.”
ORIGINAL STORY: Many years of unsuccessful snow dances have compiled themselves into a February that will go down as one of the top snow events in history for the Puget Sound region.
To stay in a continuous cold and snowy pattern on this side of the Cascades is a very rare thing, as it takes an area of high pressure in the Pacific Ocean to force the jet stream north and then down the BC coastline. While this is occurring there also needs to be high pressure in Canada allowing cold arctic air (modified arctic air by the time it reaches us) to funnel through openings in the topography, such as the Fraser River Valley.
This weather doesn’t leave us with much of a break as another system clips our area Sunday evening. This system is a quick moving one, likely leaving 1-3” of snow before it boogies out of here. Don’t let this lighter snowfall fool you, it will quickly be replaced with a larger and more potent snowmaker on Monday afternoon or evening.
Current models believe Monday’s storm could be a similar setup to Saturday night’s event. Here in the foothills, we might not win the snow trophy, as drying east winds could once again eat into our snow totals. Virga, the process of moisture evaporating before reaching the ground, could dominate the atmosphere above us. This will need to be monitored, but our snow loss could mean big gains for Seattle and locations up against the eastern Olympics. As our east winds ramp up, they push clouds away from us and up against the eastern side of the Olympic Mountain Range and wring out snow.
The National Weather Service has issued a back-to-back Winter Weather Advisory and Winter Storm Watch for the Puget Sound region, again warning of heavy snow with two storms heading our way. The advisory runs 4PM February 10th, through 4AM, February 11th. After the 1-3 inches with Sunday’s system, Monday’s storm – for which the storm watch was issued – will move in quickly and bring the possibility of 5-8 inches of more snowfall by Tuesday. The storm watch runs 10AM, February 11th through 6PM, February 12th.
NEW: As of Sunday morning, the National Weather Service was also warning for the possibility of freezing rain and sleet with Monday’s storm that will be pulling in some warmer air with the precipitation. See image below for details.
Taking a look at the weather models, we see more systems potentially reaching us on Thursday and into the weekend, with temperatures just above or below freezing. Snow should be observed with all these systems, but ground temperatures could be borderline for snow accumulation depending on the time of day. You’ll want to keep your eye on the forecast, as later in the week is too far out to provide the details one will need to determine if one should travel.
If some of you have a special sun dance for 80 degrees and sunny, now might be the time. Some of the long-range models believe this cold blast has the potential to keep us in its icy gripe for another week, with some signs of it lasting through the end of February.