Drivers try to push a car out of a multi-vehicle wreck on an icy hill in Kirkland on Thursday.

Many school districts throughout the region again closed or delayed classes due to ice and snow (see complete list).

And dozens of bus routes were disrupted by the snow, leaving many commuters waiting in the subfreezing cold at stops for buses that often never arrived.

The snowstorm was ushered in by booming thunder that echoed eerily across the region and sent flashes of lightning piercing through the early morning darkness.

Snowfall that was expected to stop by late morning continued without letup into the early afternoon, as forecasters extended the window for the snow showers until 6 p.m.

Traffic was completely stopped at times on parts of State Route 520 on the Eastside as snow covered the highway, and some drivers abandoned their cars and began to walk down the freeway.

Some drivers were even turning around and using the shoulder to drive the wrong way on Highway 520 in an attempt to get off of the highway - a maneuver that state Transportation Department officials said was very dangerous and inadvisable.

Seattle-area motorists more accustomed to rainfall did their level best to battle with the snow, but often the snow came out the winner.

One of those who lost the battle was Mary Prince, who got caught in a 12-car pileup near Kirkland Thursday morning.

"We got on the hill, and it was all a bunch of ice," she said. "Everybody started going this direction and started piling up. You don't feel like you're in danger so much - you just feel helpless.

Bellevue city officials asked people to stay off of the roads as near white-out conditions early Thursday brought 3 to 5 inches of snow throughout the city.

Throughout the region, crews are working to clear emergency routes and primary arterials routes before the forecasted hard freeze settles in and turns the snow to ice.

A vigorous Convergence Zone that brought 6-18" of new snow Wednesday afternoon and evening in the northern interior areas moved south early Thursday morning, bringing snow into the Seattle-Bellevue metro areas. The now began to fall in Seattle after 5 a.m.

State troopers and local law enforcement officers are responding to spinouts and crashes as drivers encounter compact snow and ice in areas that saw snowfall Wednesday, and new snow showers were catching many drivers off guard.

On I-405, I-5 and I-90 in King County, traffic was snarled in many areas. DOT officials have plow and de-icer crews out, but the snow was coming down faster than it could be cleared.

Throughout the region, side streets and hills continued to pose a problem for drivers, with a steady stream of collisions being reported. Those who decided to leave their cars at home and take public transportation were only a little better off, as many buses could not reach all roads on the schedule routes, and some were involved in accidents.

Despite the large number of collisions Thursday, there were no serious injuries reported.

In Kitsap County officials said freezing weather may have claimed the life of a man who wandered from his house wearing only light clothing. The sheriff's office said John Clarence Makepa Basso, 36, had been suffering from a medical condition and had observed him behaving erratically recently. He was found dead in a heavily wooded area near his residence Wednesday afternoon

Snow is expected to continue at times through the early afternoon, accumulating as much as 2-6" of snow, with the higher amounts expected on the Eastside and into the Cascade foothills. More thundersnow is also possible.

Snow will also likely expand and drift south to about the King/Pierce County line. However, Pierce County will see snow showers this morning rolling in off the coast.

Forecasting models also show perhaps another band of snow forming and stretching into Tacoma to Olympia areas this afternoon, potentially bringing 1-3" of snow there, but that is uncertain.

A WINTER WEATHER ADVISORY has been extended until 6 p.m. for the greater Puget Sound area. In the Strait of Juan de Fuca area, the advisory is in effect until 4 p.m. for another 1-3" until this time.

For South Sound and Southwestern Washington, the advisory has been extended until midnight, where scattered snow showers will continue until then, putting down 1-3" in individual cells.

Thursday's snow is just part two of a major snowfall that dumped 1-2 feet in parts of Skagit, Island and northern Snohomish County through the day Wednesday. Steady snow fell for most of the day there as the Convergence Zone stalled over the area. A spotter outside of Arlington reported 23" as of late Wednesday afternoon.

Snow Totals So Far

Here are some unofficial snow totals with this storm:

• Arlington (Outskirts): 23"
• Darrington: 23"
• Concrete: 21"
• Elwha: 20"
• Sedro-Woolley: 18.5"
• Mount Vernon: 14.5"
• Randle: 14"
• Sultan: 13"
• Bellingham: 13"
• Monroe: 12.5
• Port Angeles Outskirts: 10-15"
• Hamilton: 12"
• Redmond (Novelty Hill): 10"
• Hoodsport: 10"
• Stanwood: 10"
• Onalaska: 10"
• Grand Mound: 9"
• Oak Harbor: 7"
• Anacortes: 6.5"
• Hamilton: 6.2"
• Kirkland (Rose Hill): 6"
• Beacon Hill: 6"
• Olympia: 6"
• Marysville: 6"
• Woodinville: 6"
• Rochester: 6"
• Granite Falls: 5.5"
• Clearview: 5.5"
• Sekiu: 5"
• Mercer Island: 5"
• Tumwater: 5"
• Neah Bay: 5"
• Chimacum: 5"
• Orcas Isl: 5"
• Mukilteo: 5"
• Ferndale: 4.5"
• Bainbridge Island: 4"
• Lynnwood: 4"
• Port Townsend: 4"
• Port Orchard: 4"
• West Seattle: 4"
• Potlatch: 4"
• Lacey: 4"
• Arlington: 4"
• South Everett: 4"
• Friday Harbor: 4"
• Mill Creek: 4"
• Ravensdale: 4"
• Bellevue: 3-4"
• Redmond: 3-4"
• Ferndale: 3.5"
• Gig Harbor: 3"
• Lopez Island: 3"
• Hoodsport: 3"
• Freeland: 2.5"
• Shelton: 2"
• Kingston: 2"
• Bothell: 2"
• Seattle (Seattle Center): 1"
• Tacoma: 1"
• Mountlake Terrace: 1"

What's Up With This Convergence Zone?

Convergence Zones are caused by colliding winds -- a north wind from the north and a south wind from the south. When those winds collide, they get forced upward, where the air condenses into clouds and storms form.

Zones historically are responsible for some of the area's greatest snows, and this one was no different. Arlington had a snow report of 23" as of 10 p.m. Wednesday, and all that snow that fell into Skagit and Snohomish County from about noon on has been at the hand of these colliding winds.

The massive snow storm of Dec. 18, 1990 was also born from a Convergence Zone that set up shop over Downtown Seattle, as was the snow and freeze of Nov. 29, 2006 (sort of a mix of a convergence zone and arctic front for that event).

This time, the zone had a stronger southerly component, keeping the zone up north for most of the day Wednesday. Computer forecasting models correctly predicted this zone's formation, leading to forecasts of heavy snow in the Seattle area Wednesday afternoon, but underestimated the storm's southerly wind component, keeping the zone north of the city. It wasn't until Thursday morning that this southerly component weakened, allowing the north wind to gain strength and push the zone south.

Zones form quickly and can shift very quickly, and many times there is not much time to react, as we are finding this morning. As much as this is snarling the Thursday morning commute, imagine if this happened at 1 p.m. Wednesday when everyone would have been in school.

Where Do We Go From Here?

The zone will continue to drift south into southern King County through the morning, then fizzle out. Cold air will then push in from the north, making for a very chilly day. Temperatures may be stuck in the upper 20s to low 30s through the day.

The air will also be unstable for a while, leading to scattered hit-and-miss snow showers through the afternoon. Each shower could put down an additional 1" or so in individual cells. But the sun might pop out in between.

Thursday night will be clearing and cold, with lows in 15-21 range. That means a hard freeze to all that is on the ground today.

Friday should be a lot like earlier this week -- sunny but continued cold -- possibly a few degrees colder than this current spell -- with highs 25-28 and lows Friday night from 10-18.

Saturday also looks dry and continued cold with highs in the mid 20s. But clouds will increase Saturday night, keeping lows around 20.

Those clouds are a signal of our next great forecasting challenge -- a storm heading in for Sunday. This one presents a whole new set of variables, because Mother Nature has a devious sense of humor and a thick playbook, it seems.

This storm is coming in from the west/northwest, and it looks pretty wet. Second, we'll not only have some arctic air here in Western Washington, but even more in Eastern Washington. That air is very dense, and thus has higher pressure.

As the low pressure of the storm approaches, forecasting models are hinting now that we could see some very strong, gusty east winds in the passes to the usual North Bend, Enumclaw, Gold Bar east-windy places -- perhaps as high as 40-50 mph.

That's challenge A. Challenge B -- if so, that would be blowing in a lot of cold air from Eastern Washington into Western Washington -- the "North Bend gets to feel like Bellingham does now for a while" scenario, getting even more cold air into the region ahead of this storm.

So when the storm arrives, in the areas outside the wind, depending on how warm the storm is and how much cold air is around, it'll likely start as heavy snow, then gradually change to rain.

But in areas where that east wind keeps feeding the cold air in, this could present some freezing rain problems along the I-90 corridor. (Portland people can tell us all about this, since they have frequent experience with a similar set up with the east wind blowing out from the Columbia Gorge. In fact, this set up presents them with similar freezing rain problems for their area.)

Bottom line: Sunday could be real messy. It might be lucky for us if the system comes in cooler and it stays as snow because while it'd be quite a bit of snow, ice/freezing rain would be worse. (About all that's left is the blizzard and we'd have collected the entire set of weather problems :) ) Highs will be somewhere between 31-38.

Some lingering snow showers Monday, then we dry out again for the afternoon into Tuesday with partly to mostly sunny skies and highs in the low-mid 30s and lows still in the 20s.

Another not-so-frigid system moves through on Christmas Eve, but at this point, this is looking like the kicker of just snow to rain and highs into the 40s, perhaps ending the cold spell. But a more southerly track, and we could get that White Christmas after all :)