SEATTLE -- I know it's spring break for many, but here's a little pop quiz (it's not too hard, I promise!):

Which one of these items does not belong?



(OK, if you picked A, you get half credit because... how often is Easter in March?)

If you picked B, you are in the same group as weather forecasters who are amazed that here it is a few days from April, and snow fell across many areas of Western Washington.

Most of the snow fell across Southwestern Washington and the South Puget Sound area as an area of low pressure crossed the southern half of the state, although we had isolated reports of snow along the northern Olympic Peninsula.

Snow totals generally ranged from a dusting to 1", but the eastern Pierce and King County foothills got a little more as the snow stalled over the area.  Reports from Bonney Lake, Enumclaw and Eatonville were anywhere between 3-4".

And believe it or not, a few spots of snow remain in the forecast for the next few days as a ridiculously complex pattern sets up shop, made even more challenging by the fact that if you think it's hard to get snow in January, it's much more difficult to get it in late March.

A very cool air mass is settling in from the Gulf of Alaska, and on top of that, we have two low pressure systems drifting through to provide some moisture.

Generally speaking, snow levels are around 700-1,000 feet during the day and 500 feet at night, but the air mass is set up that any kind of decent intensity in a passing shower could temporarily lower the snow level down to the surface. That's what was happening Wednesday evening, and will be the case through perhaps Saturday morning.

TONIGHT:

Tonight will feature scattered rain or snow showers. The steady band of light snow in the South Sound was moving off into the mountains but a Convergence Zone had formed in the system's wake, and was centered over the South King County area, keeping a sloppy rain/snow mix going there, with snow farther east above 500 feet. Outside the Zone, we'll have scattered hit-and-miss showers in its wake, so no more widespread snow expected overnight.

Here is the breakdown of snow possibilities:

* Snow levels will generally drop to about 500 feet, meaning the hilltops could see some slushy accumulations of about an inch in passing showers.

* Southwestern Washington -- spots from Shelton south through Oregon -- the main steady band of snow that moved through there this evening was moving off into the mountains and so steady snow is done. Snow or rain showers are still possible. (As for why it snowed below 500 feet here, see explanation below.)

* A Puget Sound Convergence Zone that was expected to form in the usual Snohomish County/North King County area has instead formed farther south between Seattle and Tacoma and points east. This area is generally lower elevation, so it was more a rain/snow mix, but still falling as snow in the eastern foothills above 300-500 feet. Could see an additional 1-2" before the snow tapers off.

As for temperatures, we should manage to stay above freezing in most areas -- 33-34 is a good range, but the Southwestern Interior might dip below freezing, so perhaps some ice concerns for Thursday morning there.Outside those areas, we're looking at isolated rain/snow mix showers, with maybe a grassy dusting on the hilltops.  Lows will generally be in the low-mid 30s.

THURSDAY:

Generally, we still have a mix of showers and sun breaks as a low pressure system continues to rotate showers our way.

As for what form those showers will be in, it's the same deal as tonight with a mix of rain and snow showers early (snow showers most likely in the big three areas of Hood Canal, spots above 500 feet and traditional Convergence Zone area between Shoreline and Everett), then we should trend to all rain by afternoon as temperatures rise to the mid 40s.  Again, no real accumulations expected beyond a dusting in the morning. Any other place could see a rain/snow mix or even a brief snow shower in the afternoon, but no accumulations expected.  Highs will reach the mid 40s.

THURSDAY NIGHT:

We begin to run out of moisture with this system, but still some showers around with general snow level of 500 feet, but perhaps briefly dipping lower in heavier showers and putting down a potential slushy inch. Lows will be in the low-mid 30s.

FRIDAY:

Yet another wild card as a more organized system moves in.  This one also is presenting headaches since the forecasting models can't agree on where this system comes in. As the National Weather Service says in their afternoon public discussion, it could range from steady snow, to rainy and windy, to just a cold, calm rain.

It all depends on where that low comes in. You may remember we played this game earlier in the winter where if the low comes in to the south, it keeps the area in a cooler, north wind and perhaps cool enough to snow or mix. But if it comes in to the north, it's warmer but windier.

So we're going to just go with rain with possible mixed snow in the favored spots mentioned earlier, but stay tuned. As I said before, it is really hard to get snow in late March, so everything has to go right for it to occur.  Highs will generally be in the mid 40s.

HOW COME IT SNOWS LOWER THAN THE GENERAL SNOW LEVEL?

So I've just finished writing about how snow levels are generally 500-1,000 feet. So then, how is it possible to still snow near sea level?

If the intensity of a passing shower is strong enough, it can artificially lower the snow level a few hundred feet through a process called evaporative cooling.

When snow first begins to fall into drier air, that snow will evaporate. But the process of evaporation takes energy. Sapping energy from the air causes it to cool, dropping its temperature. So as this process churns away, the temperature will drop, but the humidity will rise as you add more evaporated moisture to the air content. The drier the air is at the beginning, the farther the temperature can fall during this process. (This is also known as "wet bulb cooling".)

But wet bulb cooling needs some help, and that brings up the second factor: precipitation intensity. We need to have a decent amount of oompf in the precipitation to get that cooling engine going. If it's a really light snow or flurries, it won't evaporate as much or as quickly, which means this cooling engine won't be very efficient and the temperature may not drop as much.

On the other hand, if you get a really heavy snow shower, that can really get that evaporation going and drop the temperature quite a bit. This is typically how snows in the Convergence Zone work when it snows in Everett/Lynnwood despite being in the low 40s across the rest of the region. The snow along the Hood Canal usually benefits from this as well.

That's what we're looking at in these snow scenarios the rest of this week. The one thing about this process is once the precipitation ends and the cooling mechanism goes away, the snow level usually quickly rises back to where it was before, and the temperature near the ground will rise.

Thus, it's not uncommon for the fresh-fallen snow to quickly begin to melt. And that's what we expect with these snow scenarios. Any snow that does fall should begin to melt as soon as the snow stops, as the general ambient temperature is expected to remain above freezing. The exception to this is area above the 500-700-foot snow level at night, where snow could stick around a little longer.

REST OF THE FORECAST:

There is still a chance of rain/snow mix Friday night and into early Saturday morning, but then we will start to lose the moisture and showers should decrease. Could see a few sun breaks by Saturday afternoon, with highs recovering a bit to the upper 40s.

It now looks like we will still have some isolated showers Sunday morning, so we've put a few drops on the extended forecast to cover, but it shouldn't be a washout, and what showers are out there should end by afternoon.  Highs will climb to near 50.

Monday looks dry, and then increasing clouds for early next week, with highs climbing all the way into the mid 50s. 

By then, 55 degrees might feel downright balmy. Who needs to go to Florida?