More snow Sunday afternoon; second snowstorm Monday could bring freezing rain
Current Weather Advisories in Effect:
Seattle/Tacoma & Puget Sound Metro area not including Snohomish Co.: Winter Weather Advisory from 4 p.m. Sunday through 4 a.m. Monday for 2-4 inches of new snow. Winter Storm Watch Monday morning to Tuesday for 5-10" of new snow transitioning to possible freezing rain.
Snohomish County / Northwest Interior/ Olympic Peninsula: Winter Weather Advisory from 4 p.m. Sunday through 4 a.m. Monday for 1-4 inches of new snow. Winter Storm Watch Monday morning to Tuesday for 5-8" of new snow.
SW Interior: Winter Weather Advisory from noon Sunday through midnight for 2-4 inches of new snow. Winter Storm Watch Monday morning to Tuesday for 5-10" of new snow transitioning to possible freezing rain.
Coast: Winter Weather Advisory from noon Sunday through midnight for up to 2" of snow.
SEATTLE -- Maybe you've spent the last day or so shoveling a path out of the second winter storm this month.
Mother Nature's about to ruin your work with several more inches of snow in the forecast.
A third winter storm is set to blow through the Puget Sound region Sunday evening with 1-3 inches likely, with a stronger fourth storm looming for later Monday into Tuesday with several more inches of snow likely. But it's that latter storm that has potential to bring severe impacts to the region once again, only this time, we have some new wrinkles.
Sunday's Storm First...
The storm coming in Sunday afternoon would normally cause Seattle Freak Out Level 8 but now it'll seem like child's play compared to the first two we've already been through. A weak area of low pressure is developing Sunday morning near Vancouver Island and will drift off the coast, then quickly swing inland through the Puget Sound region and I-5 corridor during the late afternoon through the evening with all of Western Washington likely to see at least some snow.
Snow is expected to develop in the 3-5 p.m. time frame and keep snowing steadily until around 9 p.m.-ish, then taper off. Most forecast charts give a general 1-2 inch accumulations with some isolated spots that could see 3-4 inches. For many it might be difficult to notice with 6-10" already on the ground, but those neatly cleaned surfaces? Buried again.
Sunday night will remain somewhat cloudy so not quite as hard of a freeze as the past few nights, but still a freeze with lows in the mid 20s to near 30.
And Then The Larger Winter Storm On Monday...
Monday morning is a very short break -- the commute will be snow-free; just dealing with any lingering issues from previous snow and ice. The Monday evening commute is not looking snow free.
A much more potent storm -- perhaps the strongest one of the bunch so far -- is already developed in the Gulf of Alaska but has its eyes set on Western Washington. But since it will have spent quite a bit of time over the Pacific Ocean, this storm 1) Has more moisture and 2) Has tapped into some warmer air. Here, the track of the storm will be critical to how the storm plays out, with multiple scenarios in play and perhaps wildly different impacts across the region.
Generally speaking, it's still cold enough already that when that storm arrives, it will begin as snow everywhere, developing from west/southwest to east/northeast Monday afternoon. Expect widespread heavy snows Monday afternoon or evening. Much like Friday, the Monday evening's commute is threatened. We lucked out on Friday that it was just warm enough that the snow didn't stick on the clogged freeways until after the gridlock eased. This may not be the case on Monday, especially if snowfall rates are heavier.
Now here's where the monkey wrench comes in: Unlike the past two storms that have tracked offshore and to our south, keeping us on the cold, north wind side of the systems and everyone with snow, this storm is coming in like a more traditional rain storm track from the west off the Pacific. Being on the north side of the storm is the snow-side as it keeps the winds from the chilly north. Being on the south side is the warmer side as you get milder marine winds from the southwest.
Thus, depending on where exactly this storm comes in, some areas -- perhaps many areas -- may see a transition to freezing rain on their way to perhaps then just a straight rain later. Heavy snow-to-freezing rain-to slush-fest on several inches of snow? Eww.
Forecast models are still disagreeing on the exact storm track; some keeping it farther south which means heavier snow totals in the region with little to no change to rain; others move it farther north which puts more of the region into the snow-to-freezing rain-to-rain possibility.
The farther north you are, the more likely this is a total snow event from start to finish. Conversely, the farther south you are, the more likely of this transition to freezing rain and maybe even rain. Where does that transition occur? That is the million-dollar question.
Right now that line is...Downtown Seattle and Bellevue. Living north of the city, you're likely to see heavier snow totals; living south of the city puts you in the higher chance of the wintry mix transition. Again, farther north you go is better chance of heavier snow; farther south is warmer and quicker change to freezing rain and rain.
Of course, freezing rain brings its own set of headaches, making power outages more likely due to added weight on trees and roads and sidewalks even slicker. Thus at least be prepared for additional power outages and extremely treacherous conditions.
Oh, and don't really think about trying to get over the mountains either, where potential for 1-2 feet of new snow is possible with Monday's storm. Winter Storm Watches in effect there too...
The snow/mix/rain will taper off during the day Tuesday with drying trend Tuesday night into Wednesday. This storm may have one silver lining in that mixing in the warmer air will push us out of the deep freeze pattern into more of a "it's just cold" pattern. More weather systems are still due in toward the end of the week, but now snow levels may occasionally push higher off the sea level floor, giving us more challenging forecasts where elevation and time of day have a say in who gets snow and who gets rain, as opposed to everyone gets snow. Easier on the commutes; harder on the forecasters' accuracy!
While we might start seeing the 40 degree mark toward the end of the week, 45 still remains elusive for the foreseeable future.