What's New: Heavy Snow Warning issued for Hood Canal area for as much as 2-5" with this storm. Updated some other snow total forecasts as well, but generally still on track for Trace-2" most areas -- perhaps 3" in the higher foothills and up north.
SEATTLE - Good news for those who are a little tired of the icy roads -- warmer weather is coming!
The bad news for you (but good news for those itching for another snow day) is, we have to go through another taste of snow to get there.
As usual with icy periods around here, the only way to warm up is to get wet, and since we're well below freezing right now, that wet means snow...at least to start.
A weakening front is moving inland tonight into early Tuesday morning. With temperatures already well below freezing Monday night and expected to stay in the 20s through Tuesday morning, the moisture with the front will begin a snow.
But the front is losing its oomph, so while whatever falls will be snow, there doesn't look like too much moisture to work with here.
The snow should begin on the coast tonight and then push into the I-5 corridor after midnight, starting in the northwest area first and spreading south and east as the morning wears on.
A HEAVY SNOW WARNING is in effect for the Hood Canal area from 2 a.m. to 10 a.m. for as much as 2-5" of snow -- with the higher amounts above 200 feet.
A SNOW ADVISORY remains in effect for all of western Washington, with the exception of the coast. The official times are from 4 a.m. until 10 a.m. -- although we think the snow might get here sooner than that.
Expected snow totals are still tough to gauge. The models are adamant that this front will bring between 0.10" and 0.40" of equivalent rain. That translates roughly to 1-4" of snow.
But looking at the satellite images, that front sure doesn't look like 0.10"-0.40" of rain. (This is where Seattle forecasters are at a distinct disadvantage in not being able to see what's going on under the clouds out in the ocean, as the radar only goes so far and no one lives out in the ocean to tell us what's going on, aside from some sporadic ship reports and buoys. Unlike the Midwest, where radar coverage to their west exists.)
Overall, we're looking at generally a Trace to as much as 2" region-wide with a few exceptions. The foothills might be more toward 3". The areas north of Everett might also eke out accumulations in the 2-3" range. And the Convergence Zone might bring an extra 1-2" later in the day to the Snohomish/north King County areas.
On the flip side, those of you near the Puget Sound shore under 200 feet or so will likely only see a dusting or perhaps even just a rain/snow mix. That should let Downtown Seattle mostly off the hook for big accumulations. Other areas that should trend more toward the dusting is along the coast -- which might not get any accumulation at all -- and in Southwestern Washington.
Depending on how much it snows, it should gradually change to rain by mid-to-late morning and then taper off and warm to around 40, quickly beginning the melting process. The exception is the Convergence Zone area (North Seattle to Everett and points west and east of there) where that could bring some extra snow showers into the afternoon even if the rest of the region has warmed up and changed to rain.
The Meteorological Mumbo-Jumbo
Had it not been so cold this past week, this front would be nothing more than a day of light rain. However, cold air is really heavy and difficult to budge. With high pressure in charge up to this point, winds have been stagnant so there's been nothing to force out the cold air.
Usually, it takes the wind and precipitation from a good front to "kick out" the cold air by mixing in some warmer air. But it usually falls as snow while we wait for the cold air to mix out.
That's the case this time. The air is cold and dry enough now to where this should start as snow. (The dry air also helps to bring snow at the start. This is Scenario 2 in our "How does it Snow Around Here" Entry in our Weather FAQ, which you can read here.)
Snow Is Not A Slam Dunk (Is It Ever?)
Of course, there are a few wrinkles in the current forecast. What you've read already is the best odds scenario, but there are a few things that make this forecast go either way.
In the "it might not snow as much" category, this front is pretty weak -- it's possible that with the dry air around, it absorbs much of the moisture and we get left with flurries or a situation like Saturday, where it didn't snow as much. We'll have to see -- as we mentioned, the forecasting models are more impressed with the system than it seems to be on satellite.
The flip side with the weaker front is, it might not do much to scour out the colder air, leaving us with less snow, but colder temperatures this week. We'll see how this system shakes out and see if we need to lower temperatures a bit next week.
What Happens After The Snow?
Assuming it does snow in the realm of expectations, we should change over to rain and taper of to showers for Tuesday afternoon. The exception is the Puget Sound Convergence Zone, which might form in the afternoon and be strong enough to keep snow levels near 300-500 feet between Northgate and Everett...which most of that area is above 300 feet. (Near I-5, Shoreline's about 400, Lynnwood is around 425, and Everett is around 450-500).
Bottom line there: Some wet snow may keep falling in that area.
Just a few isolated showers Tuesday night. These might mix a few snowflakes in as lows will drop to the upper 20s and low 30s, but we should be out of moisture by the time the temperatures drop that low.
We're back to dry and partly to mostly sunny for Wednesday and Thursday, with highs in the upper 30s and lows in the 27-31 range -- or we might need to drop the temperatures a notch if this system Monday night doesn't do much to scour us out. Either way, that means we'll at least have to keep an eye for some icy roads both mornings, but shouldn't be as solid a freeze as the past few days.
Long range models are in disagreement for late Friday and Saturday, some bringing a little light rain, others keeping us dry. The dry one has been sort of flopping around on its own lately, so we're going to keep a chance of showers in the forecast -- especially for Saturday -- but it's pretty light. Temperatures by then should be back into the 40s (I know, we've been saying it for days now) so it'll be rain, and hopefully all our ice is gone.