Sunday, January 15, 2012

Sunday Morning Snow Update

More serious snow this morning in many locations....and a very different situation.  Looking outside my window in north Seattle the scene is completely white, moderate snow if falling, and there is perhaps 3/4 inch on the ground.  Really pretty.

Yesterday the snowfall was quite varied...with nothing to an inch over much of the lowlands, but several inches in the convergence zone (e.g., 3 inches in Snohomish).  Here is a snow map 7 AM this morning from the CoCoRahs network (click to expand)

Here is the 24-h precipitation from Seattle Rainwatch--probably corresponds well to the snow distribution right now:

The temperature of the atmosphere is much cooler this morning than yesterday and virtually all precipitation is going to be snow.  Here is the latest temperature structure from Seattle SnowWatch:
Now I will show you something NEVER seen before on this blog or anywhere else..the precipitation type output from the dual-polarization capability of the new coastal radar and the old Camano radar. Light blue (DS) indicates dry snow.  Remember the beam increases in height away from the radar.


Looking at the radar loops and the latest surface reports indicates a low is now centered south of Grays Harbor--a location that allows precipitation to circle back up into western Washington. At the same time there is a band of snow down the Strait towards Whidbey.
Each forecast run the last few days increasingly suggested this location for the low ...and this morning's run shows it clearly.  Looking at the latest Langley Hill radar image we can
 see showers offshore circling around and then moving up into western Washington.  Snow on the coast, of course.  The band down the Strait into NW WA is fascinating...it represents the convergence between southerly flow moving up the Sound and northerly or weak flow moving out BC.  What makes it exciting to me is that the models were suggesting this yesterday.
There is a gradient of snow east-west across the Sound..more on the east side, due to Olympic "snowshadowing"

This situation will keep up for a few more hours, but the low and the snow will slowly move south, causing a drying out this afternoon...from Olympia north.  Sorry snow lovers!

But the best is yet to come.  We will have a break the second half of today and much of Monday.  But later Monday afternoon into Tuesday morning another batch of snow will come in with another upper trough and this could be considerably heavier.

And then Wednesday morning we may have snow/rain SLUSHMAGEDON. A very warm, wet system will approach...first we could have heavy snow and then heavy rain.  Possibly a big mess.

And remember the mountains are getting lots of snow...over a new foot at Stevens. They needed more snow and will get it.  But the avalanche risk will be increasing.

So to summarize:  This situation has four stages:

Stage 1:  Snow with the front yesterday, with convergence zone snow.
Stage 2: Today's snow with the coastal trough
Stage 3.  Later tomorrow snow with another trough
Stage 4:  SLUSHMAGEDON on Wednesday AM.

The current model runs suggest that the next week will bring some of the most intense and active weather in a long time...windstorms, rain, snow....the trifecta of NW weather.

Do you Live In or Near Mountlake Terrace?
If so, please keep you eye out for my lost dog..see the picture and more information in the right panel.  Thanks. Also message for the City of Mountlake Terrace:  Please Don't Pull Down and Tear Up Our Lost Dog Signs!


51 comments:

Jennifer McNeely said...

here is west seattle by the ferry NOTHING! Will we get left out?? So bumming! Whats the word?

AngelF said...

Oh I can't wait to bike under the Slushmaggedon mess next week (sarcasm). No but seriously, gonna make this a twitter hashtag .

Ferdi said...

I really don't mind being in Hawaii right now, although I'm missing some good photo ops in the NW.

chrisale said...

Great update Cliff thanks! I'm hoping we are far enough north that we get 100% snow here in Port Alberni on the Island. The weather network is calling for 20cm (8") for us for Wednesday.

Love that new radar! It's even useful to see what's coming our way into Barkley Sound. I've been bugging the powers-that-be to put a radar in or Tofino for a long time, the coverage on the West Coast of the Island is terrible.

cornbread said...

Just stated to snow here in south Bellingham. I have been watching it slowly approach from across the bay since it was light enough to see this morning. There was sun to the east, and clouds to the west, slowly coming this direction.

While walking the dog down by the water you could see two separate snow areas with clear sky between them.

Colleen said...

I'm slowly coming to realize, Cliff, that your brand of "intense and active" weather is meaningless here in north Whatcom County. Guess it just goes to prove that we really are in our own little world up here!

Kevin said...

Snowing moderately in Bellingham right now - nothing on the ground, yet.

Reading the forecast discussion, it looks like there is a scenario where the NW Interior stays cold throughout the weds/thurs storm, with the storm tracking south of us, pulling down Frasier outflow. Do you see this as likely Cliff?

Thanks for the blog btw, I think the nowcast is working great!

Amy said...

I'm up on Finn hill in Kenmore and it hasn't stopped snowing since I woke up at 9AM. Totally unscientific measurement but we have a few inches of accumulation and it looks like a winter wonderland.

snapdragon said...

Finally getting a few tiny flakes here in the Hazel Dell area of Clark County. Hoping it will pick up and stick, but...

DomainGamer said...

Coming down hard in the normandy park area, started around 11:30am.

Megan Baldwin said...

Everything is totally white in Seattle. I can't even see the sky scrapers or anything because snow is so heavy. I'm seriously considering cutting work early and going home at this point. haha. It looks nuts.

DGBell said...

Ground is covered here on the coast(Raymond). Probably have about 2 inches and its 34 degrees. Still snowing lightly. Love your blog Cliff and thanks so much for the frequent updated posts!

Unknown said...

Thanks Cliff, really like that you are doing an update and snow nowcast. During the week, there is nothing better than snow nowcast so people can decide whether to leave early or not.

That Wed am warm front coming in from the SW over the cold air is the perfect snow setup. It does appear that it changes to rain however many times it gets underestimated how long the cold air can hang tough if the low stays south of Olympia. Right now it looks very close (NAM is just south of AST which would be big snow but it is the outlier). You said it, the trifecta! I'm more worried about these potential wind storms by next weekend than anything else but too far out to call. Justin

Jeffery said...

I photographed a hummingbird in the snow today: pic.twitter.com/EpRlElKy

rainycity1 said...

Cliff, the UW atmospheric radar site has been a great resource this a.m.
Wish we'd had access to it last evening while traveling up from Camas WA!
http://www.atmos.washington.edu/weather/radar.shtml

rainycity1 said...

I can't believe how fast this happened in W. Seattle
11:45 a.m. - bare roads, no precipitation
12:15 a.m. - snowing steadily w/ surfaces covered.
1:30 p.m. - over 8 cm (3 in) and still coming down

Unknown said...

Always love the blog Cliff! Got a solid 6" in the hills 3 miles N of Monroe, about 400' in elevation. Power has been off more than on in the past 24 hours... but it's a beautiful winter wonderland here!

Upupaepops said...

It was very interesting going from home in downtown Redmond to work in Canyon Park, off I-405 in Bothell

pockets of no to trace snow ( bellevue) to socked in and keeps going ( I 405 and Hwy 522 to 527) At work on top of the hill in Canyon Park there was at least 3 inches on the undriven parking lot and it was bucketing down at 1130.

Driving home over FInn HIll, near whiteout, Hwy 520 thru Bellevue at noon, nothing.

Cliff thanks for all the great education.

Lance said...

Yes! Finally some interesting weather. It's been such a boring winter before this week.

ILoveWinter! said...

Looking at the GFS for Friday at around 3:00 pm it shows a 976 mb low coming in right across the northern tip of the Olympic Penninsula/southern Vancouver Island.....I know it's still 5 days out but if this continues on this path, then how strong do you think the winds would be?

Unknown said...

5.5 inches in south kirkland at 2:25pm. I think we got lucky this time!

Paul Merrill said...

Wow! Somehow Ballard was totally left out of this snowstorm. We got NOTHING! Wah! How did it hit West Seattle and north Seattle but not Ballard?

ILoveWinter! said...

And after that 976 low passes it looks like it pulls in more cold air and a lot of moisture...are we in for a real snow storm next Saturday if the long range keeps its track?

Anna said...

In Crown Hill, we have nothing. There have been a few showers off and on all day, but nothing has stuck around. In fact, it's quite pleasant out with some clouds to the south. My parents live 50 blocks north of me and it's snowing there. But Ballard and Crown Hill got nada.

Maybe we'll get some the next go round. Feeling left out!

David B. said...

Around noon, I left my home at High Point, West Seattle, planning on taking a walk in the snowy woods at Tiger Mountain, because it had been snowing on and off all morning but not amounting to much, and I wanted to see more.

When I last checked the radar, it looked like the convergence zone was forming just south of Downtown Seattle. About 1/2 mile north of my house, around Camp Long, it was like hitting a wall. Suddenly it really started dumping and the streets went from wet to treacherous. I aborted my plans to go to Tiger Mountain and decided to take my walk at Schmitz Park instead.

There's still a pretty steep snowfall gradient here in West Seattle, and not just due to altitude. You can tell where the PSCZ stalled for the longest: the further north one gets, the more there is on the ground. Only about 2 1/2 inches here in High Point, but more like 5 in the Admiral District.

Sita said...

There's about 3 1/2" of snow in Redmond (almost the Rose Hill area) and the snow shows no signs of stopping anytime soon.

Unknown said...

4 to six inches on Lummi Island; snow ending around 12:30pm.

RobbyRob said...

VIA TWITTER HUSKYAARON who I believe interned at KOMO and is in communication with Scott Sistek in KOMO Weather - NOAA will be dropping sondes (think of them as portable observation machines) into the Northern Pacific to help stabilize the models for the storm on Tuesday. With such a big spread only two days away, and the potential for heavy snow in the lowlands, NOAA wanted to get some better observations for the models so they can start to agree with each other and narrow down on a specific scenario. The Seattle NWS office also said a Winter Storm Watch may need to be issued. This is cool stuff.

Teresa said...

According to your and coastal radar predictions it was supposed to dry out this afternoon. It snowed more this afternoon than anytime today.

ILoveWinter! said...

Cliff ~ The NWS said that NOAA is going to drop weather sensors into storm now off Hawaii to help models figure out what'll happen here Tuesday ~ I've never heard of them doing this before. Is it because the models are all in disaray or is there something they are concerned about that they want more specific info on? Please fill us in!

Megan Baldwin said...

about 2" of snow up here in the Issaquah highlands and no sign of stopping!

thejory said...

I read on Scott Sistek's twitter, that the NWS is going to drop sondes over the North Pacific to help the weather models get a little more accurate. Do they do this often? Are these the same sondes they use for upper air soundings?

freemkt said...

I guess Metro still hasn't gotten Cliff's memo about articulated buses in snow? http://seattletimes.nwsource.com/ABPub/2012/01/15/2017247337.jpg

Trace said...

Been snowing off and on all day here in Bonney Lake. We've got a couple of inches of accumulation Walter Kelly says no and cold for the next 10 days???? I sure hope not! I love the snow but as a school district employee, I don't want to have to make up a lot of snow days at the end of the school year! Thanks Cliff, love the blog!

Kelci said...

We've got a bit over two inches here in Lake City, but they've remarkably kept the main roads clear this year. I am impressed, Seattle! Way to go!

Colleen said...

Four to six inches of snow just over on Lummi Island??? What on earth?! It stayed sunny & dry here all day, and the night sky is still clear. Curiouser and curiouser....

JewelyaZ said...

Cliff,
Any chance of a Sunday-night nowcast to have a look to tomorrow's commute? The kids might be off, but a lot of us are supposed to work...
Thanks

Unknown said...

By the way, hats off to you as well as NWS. Please send the NWS people a big "well done" on this one. Lots of uncertainly, people with and without snow. The forecast verified IMO. 2" in that last snow band in East Renton Highlands this afternoon. Justin

Jonathan said...

Hey Cliff,

Now that we've got the new radar, my girlfriend and I were interested to know just how much it helps our prediction abilities. Is there any way to initialize a model without the data from the Langley Hill radar to see what we would have predicted without it?

SoftSpirits said...

This is the week i make my Cabo San Lucas reservations. :)

On a side note: Cliff, I wish i lived a little more south so i could help in the puppy recovery effort. I know it won't be long, and your baby will be back in your arms. Keep the faith.

Erick T said...

Cliff - what are the sources for your maps? In particular, I am looking for the freezing level/height maps.

Thanks!

Soupman said...

It has always been intriguing to me how these snow events evolve. I recall instances in the past where we had cold arctic air just north of us and warm, moist air coming up from the southwest and in some instances we experienced a heavy snow event. What I am curious about is what happens after the "big dump". While in some cases, the warm air wins out, the snow changes to rain and we return to "average" Seattle weather. In other cases, the snowfall is followed by a very cold, dry period where the arctic air wins out, at least for a few days. I'm just curious what conditions cause the 2 different outcomes.

Gwynn said...

Here on the banks of Miller Bay on the border of Poulsbo and Indianola we received less than an inch and it is quickly melting. I had to run to Silverdale this morning and they had absolutely no snow - nary a flake in sight.

Unknown said...

North shore of Orcas Island near Pt. Lawrence: at least 10 inches.

Unknown said...

Lake Forest Park at elevation 365 feet.

This morning:
1 3/4 inches from about 9:15 a.m. to 12:15 Temp between 32° - 34°

This afternoon:
Very light snow off and on. No appreciable accumulation. Temp between 33° - 35°

You blog is highly informative, chock full of great info. Love reading it.

lnhiatt said...

9.5 inches here in Stanwood (near Warm Beach)

Philipol said...

5" in woodinville as of 1425

Unknown said...

2.5" at 2:30 pm. in Freeland on Whidbey Island. Just came from the Mukilteo/Clinton ferry and there were 3-4" on the south end of the island.

Unknown said...

Let's go to the video:

http://www.youtube.com/watch?v=-C3ZJIl6MjY

Patrick said...

It seems that the bottom line is that we won't know about the snow until it happens. So 19th century!

Patrick said...

It seems like we won't know about the snow until it happens. So 19th century