Wednesday, February 23, 2011

11 AM NOWCAST: ACT II

We are now coming to the close of the first act of today's weather drama. To bring up-to-date with the plot.....

With westerly to NW central Puget Sound has been rainshadowed by the Olympics and virtually nothing has fallen...except for some ice pellet shows in a few locations. In fact, some places had blue skies! On the other hand, Skagit County and a zone extending westward across Whidbey and the San Juans have been hammered--some folks have gotten 5-6 inches of snow. See images at Friday Harbor and Anacortes.

And snowshowers have hit the south Sound south of Tacoma. The relatively mild temperatures (30s) have allowed roadways to be relatively decent even where snow has fallen....this IS late February!

But things are changing. As the low pressure system in the coastal water moves southward from Vancouver Island, the rainshadowing is weakening...as the flow aloft lessens and turns more to the southwest. Already we can see increased snowshowers moving into the south Sound and the rainshadowing (yes really snowshadowing) has lessened in the high-res visible satellite imagery. The pressure difference between Bellingham and the NW interior has increased and NE flow is increasing at Bellingham. The pressure difference between Bellingham and and Olympia has reversed, setting up the movement of northerly flow into the Sound. And it is at the interface between northerly flow and countervailing southerly flow where the real lowland action should happen. This is the big threat for the Puget Sound lowlands and we need to watch this afternoon whether it develops. If it doesn't the commute will be fine. If it does, you will have to deal with a slushy layer on the roadway.

This is all very complex and determined by the position and strength of the low, and the strength of the rainshadowing.

Over the short term, the zone from Everett to Tacoma is fine...but conditions should worsen after 2-3 PM. But at this point I don't foresee any major icing situation over Puget Sound roadways for commute time tonight--something I have heard incessantly on some media outlets. THIS WILL NOT BE LIKE NOV 22ND. No severe sudden freeze during the commute home.

More later....

53 comments:

superdeluxe said...

What about the morning commute tomorrow?

Lara said...

I really appreciate this "Nowcast". It helps a lot to have a better understanding of the complexity of forecasting snow. Thank you Cliff! Oh, just in case this helps, the conditions in Tacoma are occasional snow and wet/bare roads.

Farmer's Veggie Wife said...

I am so thankful for your nowcasts! I am hoping we see some snow in Bellingham though.

Rebekah Denn said...

Thank you, Cliff! I can't tell you how much I enjoy, appreciate, and rely on your thoughtful updates.

Ferdi said...

Overcast with flurries now on Sinclair Island. Wind has shifted to the NE. Got about 3 inches this morning. A northerly swell was hitting the beach on the north side of the island about 2 hours before the wind direction actually changed.

Josh said...

They should cancel the winter storm warning for Bellingham. Dry air is dominating the show.

smokejumper said...

The weather channel has a guy on Queen Anne Hill. Its just partly cloudy and green outside. I hope something gathers for ya alls.

If it happens to stay green and dry, I bet its the last time TWC will come to Seattle.

Thompsonized said...

Sunshine and light snow flurries in Ellensburg now...

keith said...

Cliff: Ten inches in my Oak Bay neighborhood (SE tip of Vancouver Island), including a half-inch accumulation in the past 45 minutes of snow shoveling. If you think Seattle is ill-prepared for snow, visit Victoria on a day like today! Maybe half a dozen blades for the whole metro area. We will send out a call for cereal and diapers in the next 12 hours!

Warren said...

We definitely got some snow up here in Anacortes. I just shoveled off 6 inches from my driveway and it looks like we are in for more. Now some sunlight is popping through the clouds and it is time to head out for some snow-ladden landscape pics!

Jim said...

Great, Thanks for the only accurate forecast of King county.

Steve said...

South Shoreline still has southerly winds at about 5mph at 12:30am.

WillL said...

It's coming down very heavy on Maury Island now. Accumulating rapidly with temp drop to 34F. Already have about .5"

Jessica Moskowitz said...

I don't think it's going to snow at all now. The temperature just keeps going up. This morning in Seattle north of the UW it was 36F and now it is 39F. Seems like a normal cloudy day to me. Thanks for being real and not super crazy like those news forecasters.

lemonlye said...

Thanks Cliff--we always check your page in tandem with the weather service for these big events!

For what it's worth: dry all day so far in West Seattle, even sunny sometimes in the morning, but a few light flurries have just begun. Staying tuned.

Branden said...

Unfortunately I was actually hoping for snow to happen bad tonight, so I could avoid some engagements. Doesn't look like that will happen? Still dry here in downtown seattle...

superdeluxe said...

Snowing heavily in Tukwila, apparently snowing heavy in Kent/Federal way and sticking?

some guy said...

Snowing heavily and sticking around Southcenter 1pm

Jamie said...

The Nowcasts are fantastic and allow me to relay the voice of reason here at work to offset the media hype. Thank you for keeping them frequent as things change!

TVN said...

Well after all this fuss (not to mention the candelling of school!), I sure hope something materializes in the Seattle area.

10" in Victoria is impressive.

Aunt Monkey said...

Well we just got our first sticking snow - just a dusting, really - down in Auburn valley. Roads still look bare and wet form my window though.

Tom said...

Snowflakes have just started falling in downtown Bellevue.

Super said...

What a piddly "storm" so far, if you can call snow showers a storm.

But perhaps the storm is just late? It looks like it, which would mean a BAD day tomorrow morning.

Pen said...

5 miles ESE of North Bend. We had 7 inches yesterday afternoon. Woke up to clear sunny skies this morning. It has now clouded over and started snowing very lightly again. NWS is calling for 3-7 inches today and an additional 3-5 inches tonight. Ha - just since I started writing this, the snow is now coming down heavy. Here we go!

Christopher said...

1:30 pm, 5+ inches on west side San Juan Island, still coming down on and off. At least one injury accident on the island.

mjgrota said...

Who needs Forman? Cliff is here to NOWCAST us through the darkness. I bet he is wearing his own yellow parka AND his slippers when looking out a window sipping his tea.

Cheryl said...

Sunny and cold in West Seattle. Definitely NO snow.

Colleen said...

I'm with Josh. The winter storm warning for Bellingham and environs isn't reality. Up here at the border it's cold, dry, and windy ~ and even the northeaster isn't as unusually significant.

Another non-event. Yawn. But keeping the snow up at Baker instead of in our barn is easier anyway...

DWulkan said...

Sun came out in West Seattle and 2:00 PM temp. is 42. Almost looks like the system is coming apart, but maybe there will be some overnight snow. In any event, things seem in delayed development.

stephen said...

kinda breezy, not too cold with blue sky peaking through here and there in West Seattle right now (1425)

gshall said...

It is still snowing lightly on the west side of San Juan Island, and we still can't see across Haro Strait to Sidney to the NW. The temp is 26 F, and the pressure is 29.77 and dropping. The wind has started to kick up, but unfortunately the anemometer is OTS.

245gt-turbo said...

Had some heavy snowfall about an hour ago here in Duvall, but it didn't stick, so there wasn't any more accumulation. Beginning to wonder if this storm is going to be like the one we had at the end of December...

mig said...

Just had a strong snow shower come through the North Slope of Tacoma (elevation 350 feet). Got about half an inch that stuck to everything but the street.

Pen said...

ESE North Bend at 700'. Well our snow has petered out.....sigh. Sun keeps trying to come out. NWS isn't giving up on it's storm warning. What do you think Cliff? Trying to decided if this is just a lull or should I actually venture out into the wider world.....

weatherlover said...

After getting almost 8 inches in just a few hours in Western Skagit County, we have now lost about 3 and are down to 5 inches. The roads are fine, but it looks like another band of snow is coming.

rich said...

Where the hell is my snow? I have no snow. I'm in Bellevue and I'll bet we don't get anything that sticks tonight.

Mikey said...

South Lake Union area ...looking at patches of blue skies. I was really hoping to bail early from work. Come 'on snow!

ken said...

Another snow bust for Seattle. When are we going to learn that when we are told of snow, it's not going to happen. The back tracking has begun from the networks.

Kevin said...

After saying all day that Bellingham will get 3-7 inches, the forecast is now for no snow at all.

Time to find the snow shovel I think....:-)

wymanbr said...

Dr Mass:

We all owe you one! Merci Beaucoups!

Bert

Dan said...

And now, a haiku.

Flakes all around us
But quiet in Seattle
Damn you, rain shadow.

Glenn said...

Starting about 3:00 pm it really dumped at Lower Hadlock. It took me almost an hour to make the 4 miles home on Marrowstone. That was with two stops to chain up. One for the rear, one for the front. I'd say 4 inches came down in that time. Building a fire in the cookstove now and will bake dinner. Still snowing heavily now (4:20)

Glenn,

Marrowstone Island

dabobman said...

Poulsbo 4:15 pm beginning to snow 1/2 inch size fluffy snow.
temp33.1F
Baro 29.73,
wind 8mphNW starting to get gusty.
altitude 270Ft.

stevemcn said...

One inch on the ground at my house in SE Renton. Streets are clean, partly sunny, threatening clouds to the W. But still can see sun on the far west horizon.

SkunkBayWeather said...

It started snowing here about an hour ago. The north wind just started and we are on the south edge of what looks like a signicant convergence zone that is forming. It is still fairly warm at 34-35, but it was 41 about an hour ago. If that weather moves south.... we could get a pile of the white stuff.

www.SkunkBayWeather.com

Heathcare for Peace said...

Just measured outside Port Townsend, 300 ft elevation and we have 5 inches.

JVP said...

Thanks, Cliff! Your blog helped me decide to drive from Port Townsend to Seattle and back last night, instead of staying over in the city. I hit a bit of black ice late at night on the way home, but good thing I came home--the Strait has been a complete whiteout since around 3pm.

athos said...

I'm laughing about how stupid it is that LWSD closed school today -- it's 38 degrees outside and not a flake all day. Classic. There is a day of summer gone.

This has been the pattern for almost every snow event this year -- it threatens, the forecast is set and then some wind or some oddity prevents snow hitting the area. Obviously, forecasters were certain snow was going to hit our area today between 10-2, then it moved to 2-3, and now who knows if/when it's going to hit. What I do know is that the kids were home all day and there was no reason for it.

sigh

scott said...

snowing hard at lake goodwin(stanwood area) for the last hour or so. 3 inches on the deck. 32 deg. 5:00pm

Charles said...

Seriously coming down in North Lynnwood/Serene Lake since 4:30, now 33 degrees and all sticking, although only about half an inch on the ground so far.

Aloha said...

Hi Cliff -
Crazy hard rain/snow mix coming down fast and furious but intermittently in lower QA - will be insteresting to see how it develops through out the evening.
But within 15 minutes the building across the street has snow on the roof - no accumalation on the street or cars - yet.

Mike said...

I have to say I feel that the NWS missed it big in B'ham. I cancelled a meeting for tonight after watching the winter storm warning and forecast Tuesday night for today. The winds arrived late and less intense, the snow non-existent...We have one inch from the last 2.5 hours. This is the second straight snow prediction that didn't unfold correctly up here.

Nadine said...

Ok for now, but what are the longer trends? Is the winter over, ir do we hold off on overseeding the pasture?
Jonathan

ps. You haveone of the more readable "word verification" algorithms out there.