The Thunderbird Returns to the Northwest: Substantial Precipitation Ahead

 There are many Native American stories about the origin of Northwest storms and rain, with my favorite being about the Thunderbird, a huge avian living in a cave of the Olympics.  When it left its high abode to hunt for its favorite prey (the Killer Whale), storms, wind, and even lightning would occur.

If there was ever a month for Thunderbird flights, it would have to be November.

A tenth of an inch represents a decent wetting, and the frequency of that amount at Seattle Tacoma Airport is shown below.  There is a clear peak:  in mid-November!   By December, there is already a bit of drying!

With this climatology in mind, let's look at the latest forecast for accumulating precipitation.

With a weather system coming in tonight and tomorrow, the total through Thursday morning is substantial, particularly on the Olympics and the coastal mountains.  

By Friday morning, the Cascades will get to enjoy the wet fun with 2-3 inches of rain.  Note the profound rain shadow over the San Juans in the lee of the Olympics.

The next week will bring much more rain, with the totals through Friday morning, 14 November, getting to 4-5 inches in the mountains.

And far more, by Tuesday, Nov. 18th.   The Thunderbird will be busy.  This is enough to result in localized river flooding and substantial progress in filling local reservoirs.

An interesting aspect of the next two weeks will be the absence of major landfalling storms, with persistent low pressure staying offshore.

To illustrate, below is the sea level pressure forecast for tomorrow (Wednesday) morning.  Huge low offshore.

Five days from now, another low will be offshore. No major power outages to be expected, with this pattern.

No "bomb cyclone" action in our nearshore waters like last year.  At least not yet.

A relief for many.

Washington is the UFO Capital of the U.S. Is it Our Weather?

 A series of reports have come out recently demonstrating that Washington State is NUMBER ONE in the number of reports per person of UFOs (Unidentified Flying Objects).

Below is the data.  During the past year, there was one sighting for every 1021 people in Washington. 

In contrast, in Louisiana UFOs are observed less than a third as often, something perhaps explained by the greater interest in Mardi Gras, alligators, and spicy gumbo.

Certain Washington (and Oregon) locations are favored for extraterritorial visitation, particularly east of the Cascade Crest and over the Olympics (see below, darker green indicates more events), 

There are three reasons why Washington State could have more UFO sighting reports:

 (1)  UFOs really are more frequent here. 

     Perhaps extraterrestrials like our salmon or are interested in Boeing. Perhaps they think Washingtonians are particularly interesting.   I would doubt it.

  (2) Washington State has a mental health issue.  

 Some political commentators might agree with this.  Perhaps folks in this state are so worried about the future of the world and the current administration that they yearn for intergalactic intervention.

(3) Our meteorology often produces features in the sky that look like UFOs.  

This is the one I would put my money on. 

It all started here.

Did you know that the UFO craze started HERE in 1947, when a pilot of a small plane  (Kennith Arnold), flying between Chehalis and Yakima, spotted a group of "saucer-like" objects over Mount Rainier?

 

A faculty member in my department analyzed the situation and demonstrated that Arnold actually saw lenticular clouds forced by Mount Rainier.

Such clouds form when relatively moist air is forced over a mountain barrier and then oscillates up and down, with upward motion producing the lens-shaped cloud (see schematic below).

As an aside, during a presidential debate on October 20, 2017, presidential candidate Dennis Kucinich admitted to seeing a UFO while staying at actress Shirley Maclaine's home near....... Mount Rainier.

Dennis Kuckinch

The Pacific Northwest, and particularly Washington State, is probably the best place in the US to see lenticular/mountain wave clouds.  

You can see them here on many, many days--either by viewing the sky or on satellite imagery.   

Why so frequent here?

We have big mountain barriers of sufficient height.

We have strong winds approaching the mountains.

We have air that is sufficiently moist to produce clouds.

Cloud like this:

Or this

Or this

So consider the meteorological explanation of our first rank in UFO sightings.

Or if you prefer:

Wind Uncertainty

The confidence in weather forecasts is not always the same.

Sometimes all the models lock onto a forecast, suggesting uncertainty is low and meteorologists can have confidence in their predictions.

But in other situations, uncertainty is large, with large differences among the forecast guidance.

The wind forecast for tomorrow over central Puget Sound is a good example of such an uncertain forecast.

One of the key tools of meteorologists for exploring uncertainty is viewing the forecasts from many weather model simulations, something called an ensemble. 

Below is the ensemble of forecasts for wind gusts in Seattle for forecasts starting early Friday.  

The predictions for Saturday are all over the place!

A low confidence prediction, at least for Seattle winds.

The key issue producing uncertainty is the path and intensity of a weak low-pressure center approaching the region.

The updated American model solution on Friday evening has a low approach coast and then passes across northern Puget Sound  (see below for forecast at 5 AM Saturday. 

Earlier today, both the European Center and NOAA HRRR models had a stronger low passing to the north, which would have produced much stronger winds (up to 50 mph) over western Washington, but they have backed off that solution.

I suspect very few will lose power tomorrow.  However, the approaching low will dump ever more rain over the region on Saturday morning.   Showers will greatly decline on Sunday and Monday, and Tuesday should be mainly dry.

Talking of rain, today's moist southwesterly flow produced profound contrasts for precipitation across the Olympics (below).  For the period from midnight through 8 PM Friday, there were 2-3 inches on the southwest side of the barrier and only .01 in Port Townsend.    That is quite a rain shadow.

Note that the largest rainfall totals are not at the high elevations but in the lower foothills of the mountains, where the moist air was initially forced to rise.  

   

Three Atmospheric Rivers During the Next Week

Three atmospheric rivers will be impinging on the Pacific Northwest, and substantial precipitation will be falling.

To illustrate, below is a plot of integrated water vapor transport (the intensity of the horizontal movement of water vapor by winds) on Friday at 5 PM.  The arrows show the direction and intensity of the water vapor transport.

Lots of water vapor pushing into western WA and BC.    Water vapor that will turn to precipitation as it is forced to rise by our local mountains.

When you get into the blue colors,  you know the atmospheric river is a strong one!

Late Monday, another (but weaker) atmosphere will make landfall

And then a monster atmospheric river will make landfall on Wednesday, with heavier precipitation in Oregon and northern California.

You want to see how much precipitation will fall?  

You bet..and be prepared to be impressed.

After the first atmospheric river (Saturday at 5 PM shown below), the Washington and BC mountains (and their windward slopes) will have received two inches or more of liquid water.

This is just the start.   

After the third atmospheric river moves through (Thursday at 4 PM shown), the accumulated precipitation totals will be stunning, with some locations getting over 10 inches of accumulated liquid water.

There will be a massive fill of regional reservoirs, and I suspect the persistent talk of drought will fade.   Of course, no more regional wildfires.

But as in late-night TV commercials, there is MORE!   The latest long-range European Center forecast for November through January predicts much more precipitation than normal over the region.

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Lots of Snow in the Mountains....and the Seattle Times Gets it Wrong Again

 First, we had strong winds, taking out the power to a quarter-million local residents.  And then snow.

The vigorous system that moved through on Sunday and a second disturbance behind spread substantial snow over the regional mountains above approximately 4000 ft., with 1-2 feet on the ground in many locations.

The image at 8 PM at the Paradise Visitor Center on Mount Rainier (about 5000 ft) was a snowy dream, with the moon illuminating a winter wonderland.

Want to see how much difference a year makes?

Below are maps of the regional snow water equivalent (the amount of water in the snowpack) for last year (left) and this year (right) for 11 PM on October 26.

Can you tell the difference? 😊

Virtually nothing last year.   Bountiful snowpack this year.

And by tomorrow at 5 PM, there will be even more (see additional totals below).

Not enough to think about downhill skiing, but a good start, and a welcome beginning to the winter snowpack after a low previous year.  

A very strong atmospheric river will approach the region on Friday-Sunday, but I will leave that to my blog.

Seattle Times Errors Again

As long as I am talking about atmospheric rivers, I can't help but note the major errors in recent Seattle Times stories on this topic.   Consider the atmospheric river graphics they provided a few days ago (below).

Not very good. 

 It starts by stating that atmospheric rivers are "flowing columns of condensed water vapor". 

Water vapor is not "condensed".  It is vapor... .a GAS.  Most of the water associated with atmospheric rivers is not condensed water (that is, clouds or precipitation), but water vapor.

Water vapor that is forced to condense into clouds and precipitation as it is forced to rise by local terrain. 

    

They claim that the water vapor is found one mile above the ocean.  This is simply false.

 The claim that atmospheric rivers "generate a series of storms" is wrong.   Atmospheric rivers are the result of larger-scale circulations and storms.   The Seattle Times confused the chicken and the egg.

This error-filled Seattle Times graphic is not an isolated example of poor research and writing. I could show you a dozen more.  Ok, how about one?

Below is their graphic about the convergence zone and rainshadow.  They have the air approaching the Olympics from the southwest (which is fine), but then they show cold air from the Fraser River Valley. Wrong, wrong, wrong. 

And then they make the same mistake about "condensed water vapor" coming off the Pacific and repeat the error of the water being about one mile off the ocean.   

The quality of the scientific "journalism" in the Seattle Times is now so poor that you really can't trust what you read in it.  Just a shame.

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The Storm Has Arrived

 The promised storm has begun.  Tens of thousands of customers have already lost power, mainly in the southern Puget Sound region at this point...and more will surely follow.

The composite weather radar image is extraordinary (see image around 7:40 PM below).  The low center was then along the central Washington coast.  We can only see this because of the Langley Hill radar near Hoquium (thanks, as always, to Senator Cantwell for helping to make that radar a reality).

A few hours earlier, the low center was also evident in visible satellite imagery (below).

As of 7 PM, winds have exceeded 70 mph on the coast and at Crystal Mountain, with and over 50 mph over the south Sound area (see below).

With low pressure along the coast and higher pressure inland, strong easterly winds from the east descended the western slopes of the Cascades, contributing to power outages from Issaquah and Black Diamond to Enumclaw and out to the Sound.

This has resulted in massive power outages in these locations (see Puget Sound Energy outage map at 7:30 PM)

In Seattle, only about 850 customers have lost power.  

The numbers increase greatly in the hours ahead.  

The latest UW/Seattle Windwatch prediction of maximum winds in Seattle suggests that winds will peak around midnight, as the low center passes to the north (see prediction below).    This early in the season, with lots of leaves on the trees and untested new growth, one can expect substantial power loss with such winds.

Showtime in 2-3 hours for central Puget Sound.  Time to make sure all my devices are charged up.

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Potential for Power Outages Saturday Night/Sunday Morning

Local power companies should organize their supplies and ensure they are fully staffed starting around 6 PM tomorrow (Saturday).

If you live in western Washington, I would charge up your phones and other devices.

A significant blow is coming from a Pacific cyclone making landfall on southern Vancouver Island.

The first strong wind of the season, particularly in October, is always a problem.   There has been substantial growth over the spring/summer that has yet to be tested by strong winds.

Many trees still have leaves, which catch the wind better than the leafless situation later in the winter.

The University of Washington modeling system (WRF) predicts a 986 hPa low-pressure system west of the Washington coast at 10 AM Saturday (see below).   On this chart, the lines of isobars (lines of constant sea-level pressure) and the wind speeds (gusts, knots) are indicated by color shading.  Big pressure changes and strong winds (gusts to 60 kt) are south and west of the low center.

Classic for an ocean cyclone.

As the low moves into southwestern British Columbia, an intense pressure variation (gradient) will move into western Washington (see forecast for 11 PM Saturday night), which will produce strong winds over the region.

The strongest winds so far this autumn.

How strong?  In Seattle, the best way to find out is by going to the City of Seattle Windwatch website (below), which uses multiple weather models to visualize the strong winds over Seattle (below).

Late Saturday and early Sunday, the forecast gusts exceed 40 mph.  My rule of thumb is that early in the season, power outages start with 30 mph gusts and are certain with 40 mph gusts.

Over western Washington, the winds will come in two steps.  

Step one, around 11 PM, will have strong southerly winds (blue colors) from Everett southward (shown below).  

The second act, a few hours later, will have strong westerly (from the west) winds surging eastward in the Strait of Juan de Fuca, hitting NW Washington

Strong southerly winds will also push northward in eastern Washington (wind gusts over the entire state at 2 AM Sunday are shown below)

Puget Sound Energy, Seattle City Light, and other utilities should be ready.

I don't want to hype this event. It is not the Columbus Day storm by any means, but it will have impacts.

Finally, as the low moves past us, air temperatures will cool, and substantial snow is expected in the Cascades.    Snowfall totals through 5 PM Sunday are shown below

The good news in all this is that wildfire season is over in Washington, and our water resources are rapidly growing again. Large amounts of precipitation are being forecast for the next ten days over our region.

Serious storms....midlatitude cyclones...are now predicted

 

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