Saturday, December 15, 2018

Heat Wave Hits Port Angeles While Strong Winds Battered the Region

The first good blow went through the region on Friday, bringing localized gusts of 40-50 mph and the loss of power to around 100,000 customers in western Washington.

Branches always fly during the first storm of the winter and even a few trees were lost.  Forecasts were decent.

But the most interesting aspect of the storm was not the general power outages and wind gusts, but the strong downslope winds and AMAZING  and sudden jump of approximately 20F around Port Angeles, on the northern Olympic Peninsula. 
Lots of power outages occurred in Seattle yesterday with the strong winds.

Here is the  observed temperature plot at Port Angeles during the past few days (time in  UTC/GMT and increases to the right).  Yesterday, the temperatures surged by 20F over roughly 2 hours, from around 46F to 65F, stayed there a few hours and then dropped to around 40 F over a few-hour period.   Talk about extreme temperature changes!

Mama MIA!  What was happening there?

The answer:  a strong mountain wave circulation forced by the interaction of increasing southerly (from the south) flow and the Olympic Mountain range.  This resulted in strong downslope flow descending into the Port Angeles area.  The air  warms rapidly as it sinks due to something known as "adiabatic compression" resulting in the brief heat wave.

Let's take a closer look at the conditions at Port Angeles during the crazy heat wave.  The plot below
shows the sustained winds (blue lines), gusts (red lines) and sea level pressure (green lines) over the same period.  There were two events (low centers) that occurred during the period shown, with the second (Friday's) being the stronger one.   Winds surged to around 40-45 kts, just as the temperatures surge.   A separate plot (now shown) indicates that the strong winds were from the south, thus descending down the steep northern slopes of the Olympic mountains. 

And look at pressure (green line)--a period of very low pressure occurred when the temperatures surged....keep this in mind, it will be important.

A plot of the temperature, wind gusts (red numbers), wind barbs, and dew point (blue numbers) show the conditions around 2 PM Friday.  Strong southerly winds reached Port Angeles (gusts to 45 knots) and you can see the localized warm temperatures (click on plot to expand).

The winds were strong enough to down trees and cause extensive power outages on the north side of the Olympic Peninsula.

So why was there strong northerly winds descending down the Olympics into the Port Angeles area?

A large-scale low pressure trough was approaching the Washington coast, increasingly southerly winds reaching the Olympic mountains.  The air pushed against mountains and a mountain wave developed over and downstream of the mountain crest.   As the air rose, it cooled as it expanded, with the cooling causing the air to become more dense, resulting high pressure on the windward (southern) side of the Olympics

Subsequently, as the air sank on the northern side of the Olympics, it was compressed and warmed.  Since warm air is less dense, an area of low pressure (or a pressure trough) developed over the northern slopes of the Olympics.  To illustrate this situation , here is a simulation of the sea level pressure (solid lines) and wind speed (shading) for 10 AM on Friday.  You  can see the high pressure/low pressure couplet and the large pressure difference between them.  That pressure difference accelerated winds to the north and down into Port Angeles.

The flow configuration is called a mountain wave, because of the wave-like up and down of the airflow, something illustrated by a SW-NE vertical cross section across the Olympics at 10 AM Friday.  The air flow is roughly parallel to the solid lines (potential temperature) see the wave-like structure?  The shading show clouds-- plenty of them on the SW side of the mountain, but none in the descending air to the NE.

And as noted above, the descending air rapidly warms, creating the warmth on the north side of the Olympics.    The high temperatures recorded in the region yesterday show the extent of the warmth, with the highest temps around Port Angeles (click to enlarge).

Clearly, the incoming flow was just right for the development of strong northerly flow  and warmth on the north side of Olympics.  But unfortunately, our friends  around Port Angeles will have to  accept  the fact that they won''t always have Los Angeles weather in December.

Thursday, December 13, 2018

First Major Blow of the Winter

I have gotten a number of complaints from Seattle weather lovers, expressing their frustration at the lack of big winds this fall.  What is a Seattle fall without a big windstorm and power outages?  Well FINALLY, we are going to get some wind, although not the kind of tree feller that cripples the region.

The forecast sea level pressure map for 10 PM tonight shows a fairly strong low pressure system offshore, with a lot of pressure variation (pressure gradient) over the coastal waters--which means strong winds there.

By tomorrow at 1 PM, the low moves into coastal British Columbia, while a strong trough of low pressure, projecting to the south of the low, is about to make landfall on the coast.  At this point, big pressure variations and strong winds are on the Oregon coast.

By 4 PM (0000 UTC) things are really cranking over southwest Washington and southern Puget Sound, as the trough moves to the northeast. Strong winds will be spreading over Puget Sound around that time.

Three hours later (7PM), a large north-south pressure gradient is over western Washington and winds will be sustained 15-25 mph, with higher gusts (30-50 mph).

Here is the forecast wind gusts from the City of Seattle WindWatch (which we developed here at the UW) at 4 PM.  Big gusts over the water (50-60 mph) and 40-50 mph over some land locations.
So can we trust the forecast shown above?  As discussed many times in this blog, to get insights into forecast uncertainty, we examine ensembles of MANY forecasts.  My group at the UW is running one of the largest and highest resolution ensembles in the U.S., and below is a plot of the highest predicted wind gusts over Seattle tomorrow from the high-resolution single forecast shown above, and a collection of ensemble members (these runs were started 4 PM last night).  

Some, but not all, of the simulations show a big acceleration of the winds after 7AM, with a peak around 10 AM.  Others have the big peaks later in the day.   So there is a lot of confidence about big winds tomorrow, but they might be delayed until  later into the afternoon.    The new ensemble will be available this evening.  The National Weather Service wind forecast last night was much less, but they updated their prediction today to include high wind warnings and watches (see graphic below).

Because the trees have not been tested by strong winds this season, expect branches to fly and some power outages.   You might make sure your flashlights have good batteries and your car isn't sitting under vulnerable tree.

Wednesday, December 12, 2018

Seattle's Darkest Day in Three Years

Here in Seattle it was extraordinarily dark yesterday.  The darkest day in years.

The total radiation on Tuesday on top of the roof of the atmospheric sciences building was .54 Megajoules (MJ) per meter squared (a joule is a unit of energy).

To give you some perspective, here is a table of the lowest daily radiation amounts since 2004 at the UW, provided by UW Research Meteorologist Mark Albright.  The date of lowest radiation is also noted.  As you can see, yesterday was the darkest since 2015, where the total dropped to .44 MJ per meter squared on December 7th.

  Year           Date        Amount of solar radiation
 2004  1229  0.64 MJ/m**2
 2005  1201  0.61
 2006  1214  0.39
 2007  1202  0.51
 2008  1225  0.79
 2009  1215  0.74
 2010  1223  0.57
 2011  1210  0.68
 2012  1219  0.48
 2013  1220  0.56
 2014  1210  0.55
 2015  1207  0.44
 2016  1219  0.68
 2017  1218  0.69
*2018  1211  0.54

The absolute worst was the obscene value of .39 on December 14, 2006.  On a day like that, you might as well stay in bed.

You will note that the darkest days are all in December, running from December 2 to December 29th.  

So why was yesterday so dark and why are December's the month of most feeble solar radiation reaching the surface?

Two things are happening.  First, a lot of deep clouds, which prevent solar radiation from getting to the surface, and second, this is the period of short days and low sun angle.

The visible satellite image at 2 PM Tuesday indicated a dense frontal cloud band right over western Washington (see below)

And the infrared image at the same time shows that the cloud tops were very high, and thus the clouds were deep.

To make it all worse, the sunrise/sunset table for Seattle shows that we are now experiencing the earliest sunset of the year (4:17 PM).  The day will continue to get shorter until December 21st.

But there is something very positive happening lately:  lots of snow has been falling in the Cascades, with all the ski areas operating this week, although not all the runs are open.    And today (Wednesday) should be a much brighter day, with some intermittent showers.

Monday, December 10, 2018

When Snow Prayers Work Too Well

The boundary between meteorology and religion has always been an amorphous one, with considerable overlap.

In ancient times, Gods were considered the prime movers of weather events, and societies were always looking for the proper supplication to the get rain, snow, or whatever else they hoped for.

But even today, with all our technology and science, folks desperately hoping for a specific weather outcome  frequently turn to praying to the powers up high.

And so it was, last Friday, when a group of snow-hungry skiers, egged on by the management of Snoqualmie Summit ski area, held a prayer vigil in North Bend at Compass Sports (see below).   They prayed, drank libations to certain weather gods, and attempted well-rehearsed weather dances. 

And it worked.  It appears that the gods heard the plaintive cries, and snow has begun to fall in the Cascades.  Before the week is up, there will be feet of white stuff in the mountains and most ski areas will be open for business.

Consider the the forecast total snowfall over the next 72h over Washington. Wow.  2-3 feet over the Washington Cascades and Olympics

Now take a deep breath before you look at the next image.  Here is the total snowfall for the next 72h.   More heavy snow in the mountains.  But there is something even more shocking....snow reaching the lowlands, something not seen since last December.  Our ski friends are going to go powder crazy.

But now the real shocker.  The latest model runs suggest the snow is not going to end.  Now take three deep breaths. 

Here is the ensemble (many model) forecast for total snowfall at Stampede Pass (4000 ft on the eastern side of the central WA Cascades) from the NWS GFS model.   The gray lines are many lower-resolution model forecasts and the blue line is a single higher resolution.  The black lines is the ensemble mean...the average of all the gray lines--normally a very good forecast. 

WOW...just continuous accumulation.
What about the best global model in the world, the European Center model?  Here is the total snowfall during the next 7 days from that vaunted forecast system:

3-4 feet of snow about roughly 3500 ft.  But no lowland snow.

The ski community is going to be ecstatic about what is going to happen.  Great skiing from next weekend through the holiday season.  The snowpack needed for summer water resources will get a huge enhancement.

But might we have too much of a good thing?  Could the prayers move in the opposite direction?  Pleading to the snow gods to turn down onslaught?  Trust me, it has happened before.

Saturday, December 8, 2018

Lessons of the Failure of Initiative 1631, the Washington State Carbon Fee, Part 1: Election Analysis

This blog will examine the failure of Initiative 1631, the carbon fee initiative, which would have placed an escalating tax on carbon-based fuels and then given the authority to distribute the funds to an appointed 15-person board.   It was the most expensive initiative battle in Washington State history, with reported expenses of nearly 50 million dollars, and it failure received both national and international attention.

Why did 1631 fail?   Did "big oil" secure its downfall?    Was 1631 essentially flawed?   These are all important questions, because we need to know how to proceed in the future.   Global warming is a serious challenge for mankind and we can't afford to waste such extraordinary resources, with nothing to show for it.  Only knowing why it failed can we find a better way forward.  This is the first in a series of blogs to analyze the situation.

Election Data

    1631 was decisively defeated:  56.6% were against, 43.% for:  a large 13% loss.   Only three counties produced a majority for the initiative:  King (mainly Seattle) voters, Jefferson (mainly Port Townsend folks) and San Juan County (see below).

The core support for I-1631 was from liberal-leaning urban and tribal areas, with most rural and suburban locations voting against.   This division is illustrated in Kitsap county, with wealthy/heavily Democratic Bainbridge Island and the Suquamish tribal areas voting for and most of the rest of the county opposing.

It is instructive to compare the I-1631 vote with than of I-732, the revenue-neutral carbon tax initiative of 2016.    Results were only slightly better (a shift of less than 3 points), with only San Juan and King County supporting the carbon tax.

There was a nice 1631 analysis published in Crosscut Magazine by some of my colleagues at the UW (Steven M. Karceski, Nives DolÅ¡ak and Aseem Prakash).  First, comparing county votes of 1631 and 732, they found a distinct pattern, with greater support for 1631 (over 732) in the most liberal/Democratic counties (King County showed roughly a 5% improvement), while ground was lost in some of the more Republican counties of the eastern side of the State).   As some post-election polling done by the Yes side confirmed, I-1631 heightened the partisan divide across our state:  few Republicans voted for it and most supporters were Democrats.

But interestingly, many liberal/Democratic voters voted against it.   As shown in the Crosscut article many voters who supported Maria Cantwell (the champion of coastal weather radar!), did not vote for the initiative (see graph below).  That is true in EVERY county of the state  That fact will going to turn out to be very important.

I attended a meeting on November 28 sponsored by the Low Carbon Prosperity Institute, which included some post-election poll results sponsored by the Yes on 1631 campaign.  The pollster,  Dave Metz of FM3 Research, found that both No and Yes sides were effective in getting their messaging out, and noted the extreme partisanship of the electorate on this ballot measure.  He found that about 25% were dead set against it (mainly core Republicans in eastern WA), about 30% were worried about climate change but thought 1631 was bad policy), and the rest were worried about climate and either supported the initiative or were willing to give it a chance.

So, which Democrats did not vote for 1631?   And how did lower-income and minority folks feel about the initiative?   Well, I decided to try my hand at election analysis using official Washington State demographic data.

First, what about income and voting preferences on 1631?  Here is a plot of percent Yes vote versus median county income for all WA State counties.  A least-squares linear fit trend line is shown as well.   In general, counties with lower income tended to vote no on 1631.  The best fit line showing this relationship explained about 30% of the variation.

What about minorities (non-white, state of WA definition)?  A lot of scatter, but a tendency for a No vote when minority percentages increase.

How about hispanic groups?  (see below).   A stronger relationship.  The three counties that voted for the initiative have low-hispanic populations and heavily hispanic districts were strongly against the initiative.

    All of these, and other, results, suggest that lower income and minority citizens of our state, many of them Democratic leaning, were uncomfortable with the initiative.  This is consistent with direct feedback I received when talking to primarily working-class groups (such my talk to facilities management folks on snow/ice conditions) and the fact that many labor unions in our state (e.g., the steelworkers and construction unions) were against it.

    I believe that the bottom line is that 1631 lost because most Republicans were against it, low income, construction/labor, and minority groups were wary of its economic impacts on their lives, and a significant proportion of climate-concerned folks, many of them long-term Democrats, were uncomfortable with aspects of the policy.  

    In fact, there was clear signs that 1631 was in trouble early in the election period--well before the No campaign started to aggressively push its message.  The Crosscut/Elway poll, based on sampling in early October, showed only 50% supported the initiative, based on a telephone poll.  Elway himself said that only measures that started in the high-50s% had much of a chance.

    But it was worse than that.  The questions told folks that "large emitters" would pay the bill and that all kinds of wonderful things would happen (see below).  Even with such a give-way, only 50% would support it.   A profound warning sign--many people did not buy it.

    In the next blog on this subject I will examine the politics of 1631, suggesting that a poorly constructed initiative, a flawed strategic plan by the 1631 folks,  an unwillingness of the population to sacrifice to deal with global warming, and a steady, disciplined effort by the No folks, resulted in the decisive defeat of 1631.

    Thursday, December 6, 2018

    Less Sad in Seattle

    Have you noticed that people are a bit happier in Seattle this fall?   More smiles and less complaining?   

    One explanation might be the unusual amount of sun this fall, which lifts the spirits and relieves the sufferers of Seasonal Affective Disorder (SAD).

    November and December should be dark, gloomy times here in the Pacific Northwest.   The sun is naturally weaker and shorter-appearing due to the time of the year.   And its feeble rays are usually further weakened by considerable cloud cover, as Pacific weather systems reach our region.

    In two days we will have the earliest sunset of the year (4:17 PM) and we are within the lowest daylight time of the year (see the sun plot below).

    Just thinking about this is usually depressing.   But not this year!  Because this year we have had unusual amounts of sun.

    Consider the solar radiation received here in Seattle (below).  We had a rough patch of low sunshine from Nov. 21 to Dec 2, but other than that we have had some relatively bright, sunny periods, including today and the last few days.

    Much less sun last year.

    Or in 2015 (which had a relatively bright period in early November)

    To get so much sun in early December is a gift from the weather gods, that provides a huge psychological boost to those of us trying to get through the winter.   A month from now, the days will be getting noticeably longer and storms will fade a bit.  NOW is when we need the sun and we are getting it.

    You may ask:  why the solar bounty this year? 

    The reason is that for the past month there has been a persistent upper-level ridge of high pressure just to our north and east, providing descending, cloud-busting air.    This is illustrated below, with a map that shows the anomaly from climatology (difference from average) of the heights of the 500 hPa pressure surface over the past 30 days.   Red indicates much higher than normal heights (or equivalently pressure).  Lots of red just to our northwest...exactly where we need it.

    Like sea-level pressure better?  Here is the difference from normal for almost the exact same period.  Higher than normal pressure (yellows and orange colors) offshore

    Ironically, a lot of our storms have been heading south into California, which has been hammered by rain, wind, and clouds.

    So turn off your light boxes and get outside will make a huge difference in your mood for weeks to come.

    Tuesday, December 4, 2018

    It is Darkest Before the Dawn, But When are Surface Air Temperatures the Lowest

    Here is an interesting question.   During a clear night and day like we have just had, when is the coldest temperature observed?

    1.  10 PM
    2.  4 AM
    3.  6 AM
    4.  Right before Sunrise
    5.  Just After Sunrise
    6.  9 AM
    Did you write it down?

    The answer is generally just after sunrise, although temperatures are pretty similar in the prior hour or so.

    Today's sunrise was at 7:40 AM.  Let's check out the temperatures at some local stations.   A good place to go for higher time resolution is the WSU AgWeather Site (every 15 minutes).  Starting with Seattle, the surface air temperature (red line) is lowest around 6:30 AM, but doesn't really rise until after 8:30 AM

    Coupeville on Whidbey Island is coolest just after sunrise

     Woodinville... just before sunrise

    Or the Weatherunderground site near SeaTac Airport (KWASEATT1683), with the lowest temperature right after sunrise

    Or how about Albro Place/Airport Way in south Seattle near Boeing Field during the past two days? (the blue line is the time of sunrise).  On December 3rd the lowest temperatures were right after sunrise.
     Just before sunrise on December 4.
    Plots courtesy of Jeff Baars, UW

    You will also notice that the highest temperatures this time of the year are quite early....around 2 PM, in comparison to 5-6 PM during summer.  And most of the daily cooling occurs between roughly 3:30 and 8 PM.

    So why are the lowest temperatures often at or just after sunrise?   With no solar radiation at night, the earth cools by emitting infrared radiation to space.  That in turn cools the adjacent air layers. But how can the temperatures continue to cool or stay the same for a while when the sun comes up?

    Good question.  Because it takes a while for the incoming solar radiation to be larger than the outgoing infrared radiation.  Eventually, the solar radiation wins, but that can take 15-30 minutes to happen.

    Tomorrow, Wednesday, morning should be similar to watch your thermometer.