Tuesday, November 22, 2011

An Extraordinary Storm

This is turning out to be a major winter storm, with serious rainfall, flooding, and winds.  And it is not over yet...some of the biggest action is yet to come.  This event is also spotlighting a lot of new technology:  coastal radars, super-hi resolution modeling, and others.

A lot of the rain is still yet to come, but consider the rainfall of the last 48h as shown in our RainWatch site:


Over five inches near the Hood Canal area and 2-3 inches extending eastward to the Cascades where precipitation picks up again.   You can add at least another inch or two to this before the event is over.  However, the real precipitation hot spot is to the south over the southern Cascades and northern Oregon coastal mountains.  Here is the latest storm precipitation total from the Portland radar (not as well calibrated as the above image) at 8:23 PM Tuesday (roughly past 48h):


Some values in the southern Cascades reaching 8 inches according to the radar.  Several raingauges there have reported 5-6 inches over the past 24 hr.

The National Weather Service is now predicting flooding on several rivers, some with moderate flooding, as seen by this figure from their website:

A particular threat is for the Chehalis River, where moderate flooding is predicted--although there is lots of rivers flooding over southwest WA and NE Oregon.  Even the Snoqualmie is getting to bankfull.  The Skokomish always floods...but that is another story.

A few of you have commented that this seems too cool for a pineapple express event and you are right.  This is not a classic pineapple express event in which warm, moist air feeds up from deep in the tropics and subtropics.  Temperatures are far more moderate and a look at the cloud shows that moisture is streaming from the southwest but not down to the vicinity of Hawaii (see picture).  In fact, some of the moisture can be traced back far, far to the west--perhaps we should call it the Sushi Express.


But the other story here is wind and we have had some amazing winds...including 97 mph at Mt. Hebo in the Oregon coastal mountains, 70 mph at Bellingham, 70-85 mph on the Cascade crests, and 60-70 mph gusts all along the Washington and Oregon coasts.  But the big action is about to happen over the Oregon coast, where the WRF high-resolution model is going for sustained 50 kt winds tonight, with higher gusts (see graphic).  If you are on the Oregon coast, you better get some batteries.
Forecast winds at 1 AM Wednesday
 The new coastal radar has been a real boon to local meteorologists during this event...telling us what is coming and how long the rain will continue.  Here is a great shot showing a front (narrow line with red embedded) approach the coast last night...a front that represented the temporary end of rain this morning:

 The models have really been good--getting the timing and major features correct.

And did I mention the over a foot of snow in the mountain passes today and more over the North Cascades.  With high to extreme avalanche danger as all this wet heavy snow falls on the light snow with embedded weak layers.  This is really a good time to be a local weather lover...more action than one can keep track of.

14 comments:

Unknown said...

Cliff, I'll be interested to hear what you think is coming for Thanksgiving day. I'm hearing possibly more wind?

But my biggest question is what's coming on Sunday the 27th... I'm going to be running the Seattle Half Marathon. Is it going to be a total washout?

smokejumper said...

I'm a pessimist, but You and the models did very well with this storm. Kudos all around.

Except the snow levels. I was really surprised how low they stayed, especially north and central Cascades with this storm.

Sushi express, lol. Sign on to Legalzoom and trademark that.

BTW, your westside misery is our our eastside delight. I wore shorts and a light sweatshirt today. It was sunny, calm, and in the 50's!!! Awesome rainshadow.

freyport said...

Love the new Langley Hill radar! Grabbed this great radar image from Weather Underground of an intense well-defined line of heavy rain (reminds me of a squall line).
Langley Hill radar image from 10:22pm 11/22

smokejumper said...

The new radar was so useful today. We can finally see fronts via radar. It swept thru last night. Pushed back north, now its parallel to the mean flow at 11 PM south of Forks.

One hour estimates are green or 15. Is that 1.5 inches an hour? Insane.

JewelyaZ said...

OK, this is TOO weird. 1 am this morning at our house, professional weather gear: 52F
3 pm at our house: 40F
11:30 pm at our house: 55F

Since when is day night?

That Langley radar sure is fantastic. I've seen a fan-out of what I suspect is essentially ground clutter or wave tops to the west of its location, but being able to see the rain on its way here is truly revolutionary.

Avalanche said...

On the NWS Seattle mainpage, there are 18 seperate warnings, watches, or advisories. Its a colorful picasso.

I don't know if I've seen that many before. That has to be near a record. Who has the graveyard shift at the NWS lol.

Bob said...

freyport, Great image! In Olympia, I found my 5" rain gauge running over just before sunset, already see another 2.6 inches now, and it's still coming down hard (after > 7.6 inches in one storm.) Yep! Pretty Extraordinary.

OlympicRainShadow.com said...

This has indeed been an extraordinary storm. It seemed like a cold front came through about mid day Tuesday, as we had a lull in precip, wind change, some sun in the rain shadow, low snow levels. I thought the models had blown it. Then we got about 8 hours of deluge with temps hanging in the mid 40's in Seattle.

Then extraordinary part, just when you'd think the whole thing had blown down to Oregon, the warm front made a serious run north. Temps in Seattle went from 42 at 5 pm to up to the low 50's in the middle of the night. Snow levels shot up, with rain all the way up above Heather Meadows at Baker. Now temps have fallen again.

It seems with this one, the fronts were just shifting around north-south in the middle of some kind of river event. Never seen that before.

Ferdi said...

Nice images Cliff! Once again we are on the edge of the weather system up here in the islands this morning. Blue sky to the northwest inching tantalizingly closer. Not holding out too much hope for sun at this pace.

Lance said...

weather is cool.

Colleen said...

Still a most un-extraordinary storm for those of us north of Bellingham. Standard late fall weather.

john bailo said...

Looks like most of the forecasts overstated the "extremeness" of the weather. Look for more of this as global warming moderates temperatures.

Joseph Ratliff said...

Nice storm for sure... I wouldn't have lost power except PSE -- when I think they were switching power sources or something switched wrong and shut our power off for 2.5 hours...otherwise during the storm there was no power outage :)

Power just flickered (almost off) again when they seemed to be "switching back" to non-storm mode.

Snoqualman said...

Well, my basement flooding rain gage hasn't overtopped yet, maybe because there have been enough breaks to let soil water drain away here in N Seattle.

I wish someone would put some more work into the color schemes on some of the maps you use. Fascinating stuff, but the way the colors jump back and forth seemingly without any real scheme can be disorienting.