Tuesday, August 15, 2017

Eclipse Weather Forecast: Looks Good for BOTH Sides of the Cascades

I didn't want to make this forecast until there was some real skill to the forecast.  Today, 6 days from the big event, I believe I can provide actionable information, although I would not pretend there are no uncertainties.  

The bottom line:  it looks good over BOTH sides of the Cascades, except for the immediate coast.

Typically, there is little skill for weather forecasts greater than 10 days, marginal skill for 7-9 days, and rapidly increasing skill for weather predictions of less than a week.  

Furthermore, we have tools, and particularly ensemble forecasts (where we run our models many times), that can quantify the forecast uncertainties and tell us when we have periods of greater or lesser predictability.  

Back to the eclipse forecast.   As most of you know, the area of totality will run across northern and Oregon, roughly on an east-west track (see map).  Totality, which can last up to around 2 minutes, begins around 10:15 AM PDT Monday August 21st along the coast and 10:25 AM at Oregon's eastern border.  10:15 AM PDT is 17:15 UTC or universal time.  Keep that in mind for later.  Seattle will have a partial eclipse (about 92% coverage by the moon), with the darkest time around 10:20 AM PDT.


The big question for eclipse watchers in Washington and Oregon is whether they should be on the east or west side of the Cascades (or in the mountains!).  There are, in fact, three major threats for watching the eclipse:

  1. Low marine clouds along the coast and potentially the Willamette Valley
  2. Smoke from wildfires
  3. A major frontal system with deep clouds (like over the past weekend)

First, lets consider wildfire smoke.  Last week, there was dense smoke over the region, much of it from the big fires in British Columbia, with an assist from local fires on the eastern side of the Cascades.  With a shift to a very different large scale weather regime, the BC smoke is now heading more to the east, leaving Oregon and Washington in the clear.  Currently (Tuesday AM) air monitors show little smoke at ground level over most of the area.


And the 48 hour forecast of the Canadian smoke model (FireWork) show little smoke and the BC smoke is heading away from us.  I expect that to continue for the rest of the week based on current model forecasts.

There are some local fires burning in our region (see current fires below), but most are small or contained, and the amount of regional smoke is relatively small away from the fires (although there is a thin veil from them).  So away from their immediate vicinity, one should not expect a major impact.

 The weather should be typical this week, with no lightning over the central and northern Oregon Cascades...so one should not expect new wildfire initiation.    Furthermore,  the eclipse is close enough to solar noon that the sun will be relatively high in the sky, and thus the sun's light will not be going through a large amount of atmosphere, as occurs near sunrise and sunset.

Bottom line:  smoke is not going to be a major issue for this eclipse unless you are immediately downwind of a local fire.

But what about clouds? 

 Here is the latest UW WRF forecast for cloud water valid at 11 AM Monday morning.  We see a lot of low marine clouds over the Pacific, but they don't extend past the coastal mountains.  Salem and the Willamette Valley would be in the clear, as would those in Washington State and eastern Oregon.  Praise to the weather gods.


What about the European Center global model, the world's best?

Here is its forecast for 11 AM for total clouds and low-middle-high clouds.   No low and middle level clouds over the eclipse zone...which is very important.  There are some high clouds over Washington and NW Oregon, but these would be thin cirrus.  An irritant, but it probably would not ruin the show. And keep in mind that the position of these high clouds is very uncertain.


As I have discussed a hundred times in this blog, state-of-the-art forecasting does not look at one forecast, but rather uses ensembles of many forecasts to judge uncertainties and to provide probabilistic predictions.   So let us look at ensembles for this event.

First, take a look at the large, 51-member European Center ensemble prediction for total clouds at Salem, Oregon. The 51 rows are from the 51 members of the ensemble, and time is in UTC (0000 UTC 21 August is 5 PM 20 August PDT).  The situation around 1800 UTC 21 August is a mixed bag, but most members have little or no clouds--roughly a 25% chance of (high cirrus) clouds.


What about Redmond, Oregon on the other side of the Cascades?  Slightly better (20% chance of some high clouds).  But there is the threat of a thin veil of smoke there.


Along the coast at Newport, Oregon?   Around 40% chance of clouds.

Checking out an independent, large ensemble systems (the US-Canadian NAEFS) for Portland (closest available), suggests a high probability of very little clouds, with only a few members indicating 10-20% coverage (bottom row).

I could show you much more, but you get the message.   The best weather technology we have suggests a favorable situation for viewing the total eclipse in the Willamette Valley and in eastern Oregon. 

 Here in Seattle there may be some thin high clouds, but you should still enjoy the partial eclipse.
The place that is iffy is along the Oregon coast.  If you are there, a short trip into the coastal mountains of Oregon should do the trick (assuming the roads are not grid locked).

I believe that model solutions are relatively stable now--but by Friday we should be very confident in Monday's forecast.  Enjoy the eclipse and make sure you are careful not to look directly at the sun.



Sunday, August 13, 2017

Wildfire Smoke Brought Radioactivity and Ozone

Now many folks were unhappy with the low visibility and dismal skies during our wildfire smoke period.  And I know a number of you were discomforted by the particles in the air.

But there is more.   According to U.S. government measurements, radioactivity and ozone were higher as well.

I wasn't aware of the radioactivity issue until I received an email from Tim Celeski of WeatherOLA.com who provided a link to the Environmental Protection Agency's RadNet website (another good reason why we need EPA, by the way).

Here is the gamma radiation count from Seattle. Gamma radiation is very high energy electromagnetic radiation and are capable of ionizing (stripping electrons) from atoms.  Values jumped up on August 3, when the smoke reached Seattle and started to decline yesterday.  Note that is a logarithmic scale so the jump is significant.

 They also break the radiation down by energy range.  Similar story.


Wildfires inject burned and other materials into the air, and if any long-lived radioactive materials (like Cesium-137) attach to the smoke particles, they can travel substantial distances.  As noted by two colleagues of mine at WSU (Brian Lamb and Yunha Lee), such suspension of radioactive material by wildfires has been observed and studied before.

So where did the radioactivity come from in the soils and plant materials in the area of the BC fires?  I am no expert in this, but one could speculate there could be deposition from the Fukushima event, the remnants of previous above ground atomic testing, or perhaps natural radioactivity in the soils.   Perhaps one of you knows more about this.


And then there was ozone...VERY high levels of ozone that were produced by the numerous BC fires.  

Fires produce nitrogen oxides and hydrocarbons that can combine to produce ozone. . According to my UW Bothell colleague (and a specialist in NW atmospheric chemistry)  Dan Jaffe, the ozone levels were stunning.

8hr average values at Enumclaw hit 103 and sites near PDX reached 116.   And many sites that don't usually exceed the standard, like Eugene, were way over.

This chart shows maximum 8-hr ozone averages on August 3.  Reds are very high.

The U.S. ozone standard is based on a maximum amount of 70 parts per billion (ppb).  Specifically, an area will meet the standards if the 4th highest maximum daily 8-hour ozone concentration each year, averaged over three years, is 70 ppb or below. Ozone can irritate the lungs and sensitive nasal passages.

In total, Enumclaw has been over the 70 ppb standard  for 8hr on 8 days since 7/31. Wow.

How about Mud Mountain Dam (near Mt. Rainier) and Issaquah (see below)?  Lots of times above 70 ppb!


According to Dr. Jaffe, we have not seen O3 like this in decades.

So with smoke adding lots of particles into the atmosphere (documented in previous blogs), high ozone levels, a depressing sky with little visibility, and some radioactivity thrown in for good measure, it is no wonder some folks were not feeling so good during the last week.

Friday, August 11, 2017

The End of Smoke, the First Rain, and Cooler Temperatures Return: But Are There Dangers with this Change?

We are about to experience a major shift in our weather, one that will end the above-normal temperatures, bring the first real rain of summer, and push the smoke away from western Washington.  Normal conditions will return.

But as we will see, there are some dangers to this change, including pole fires, power outages, more wildfires, and slippery roads.

During the past week, a ridge of high pressure has dominated the flow over our region, as shown by this upper level chart for Tuesday at 5 PM.  It has been a very stable pattern, resulting in warm conditions and light winds.  The smoke settled in over our region.

But the models are emphatic that the ridge will move inland, and a Pacific trough will approch us.  The forecast map for Saturday at 5 PM shows you what I mean.

Today (Friday) will be the last warm day before the change, with temperatures rising into the lower 80s.

But Saturday will be a different story, with increasing clouds and wind from the approaching disturbance.  The smoke will be pushed eastward.  And even some light showers are possible.    The major rain will wait until Saturday night and Sunday morning.

Here are the 24-h total precipitation forecasts for next few days.  For the 24 h ending 5 PM Saturday, light showers over western WA and what looks like some convective (thunderstorm) precipitation over eastern Oregon.  It is good the eclipse is not tomorrow!


But the next 24 hr (ending 5 PM Sunday) is much wetter over western WA and the coast.  No much by winter standards,  but the most we have seen for months (roughly .1 inches over the interior and .5 inches along the coast)


Now what are the potential downsides to this change of weather?

1.  Slippery roads.  The first rain of the late summer falls on roads that have accumulated oil, dust, and other particles, often producing a transient slippery surface.  So drive carefully when the rain starts.

2.  Pole fires and power outages.   According to a retired City Light employee I have worked with, the dust and muck deposited on wooden power poles can become conductive with a little rain, causing short-circuits, fires, and power outages.  The long period without rain this summer makes us particularly vulnerable.

3.  Lightning.   The approaching trough can initiate thunderstorms that could start new wildfires over the Cascades and eastern WA/Oregon.  And yes, perhaps endangering a few golfers.

I suspect most of you will be happy with the return of normal weather.  

Many are starting to think about the eclipse.   Well, the latest upper level (500 hPa)  forecast from the National Weather Service GFS model for 11 AM Monday morning (21 August) shows a trough, with clouds and showers, over the region...not good!   But don't worry.... the skill at 10-11 days is very poor.


Thursday, August 10, 2017

The Ultimate Wildfire Smoke Video for Puget Sound

Greg Johnson of Skunk Bay Weather has produced a marvelous video from his site on the northern Kitsap Peninsula showing the changing effects of the wildfire smoke during the last week.

What he did was to combine video of the sunrises from late July until today, with the first showing clean air conditions, and the latter ones reflecting the effects of the smoke.   It is just stunning.   Click on the link to check it out.




And now the good news. Friday will be the last day of above normal temperatures for a while. Over the weekend the large scale flow pattern will shift, with much cooler air moving in.

Rain will return.

The smoke will be blown away from Puget Sound.

Clouds will again grace our skies.

And some folks will stop claiming the smoke is a sign of global warming.

_____________________

Eclipse forecasts.   It is too earlier to do so skillfully, so my first analysis of the eclipse weather will be on Monday.



Wednesday, August 9, 2017

Believe it or Not! Wildfire Smoke Is Cooling the Northwest

Today was another warm day, with Sea-Tac hitting 91F and temperatures rising above 100F in the Columbia Basin of eastern WA (see map).


But do you know that our temperatures this week would have been much warmer this week if it weren't for the substantial smoke covering our region?  Smoke that predominantly came from British Columbia?  Believe it or not, the proof is at hand!

The plume of smoke above us has reduced the amount of solar radiation reaching the surface...thus producing less surface warming.

Why is that true?  Because the smoke particles both scatter some of the solar radiation back to space and absorbs some of the sun's rays, the latter causing the air higher up in the atmosphere to warm.  By either mechanism, less solar radiation reaches the surface.

  Here at the University of Washington, the amount of solar radiation reaching the sensors at the top of our building has been substantially reduced by the smoke:  the numbers are shown below, dropping from 25.37 on August 1 to around 19.15 MegaJoules per meter squared on August 5-6.  Roughly a 25% drop in solar radiation!

Radiation in MJoules per m2
7/31   26.80
8/1     25.37
8/2     23.22
8/3     22.55
8/4     23.33
8/5     19.19
8/6     19.14
8/7     21.09
9/8     22.62

OK, the amount of solar radiation is less, but how can we prove that it cooled us off? 



To explore this issue, I asked Jeff Baars, a research meteorologist in my department, to explore the smoke's impact by taking difference between the UW WRF model forecast for surface (2-meter) air temperature and observations.  The UW WRF model does not include the effects of smoke (we are working on it!), so the difference between our model forecast and reality should reveal the effects of smoke.   The expectation is that the model without smoke will be too warm...but by how much?

Here is the difference between the forecast (72h) and observed temperatures at Seattle-Tacoma Airport from 23 July through last night, for the forecasts valid at 5 PM each day.  The various colors are for different resolution UW WRF forecasts (36, 12, 4, and 1.3 km grid spacing).  Before the smoke reached our region the WRF model forecasts were quite good, with very small errors.  But after the smoke hit, the errors reached around 10F, with the model being too warm.   Implication:  the smoke cooled Sea-Tac by 10F on two days, and less amounts on others!


What about Bellingham, a location even closer to the smoke source in BC?    Wow... the cooling effect of the smoke reached 12-14F!


Portand?  The smoke took a bit longer to get down there, but when it did, the temperature effects were substantial (see graphic).  The model seems to be 2-3F too warm before the smoke hit, but when it did (August 7-8), the cooling effect was large (over 10F).




We did a similar analysis for 5 AM, when temperatures are near their daily low, and found little effect.  This is not unexpected:  much of the smoke is higher up, where the air is cooler and the smoke particles are relatively small compared to the wavelength of infrared radiation, which is the key player at night.

The smoke was substantial today and even worse this evening, something shown by the small particle concentration (PM2.5) at Seattle and Tacoma (see below from Puget Sound Clean Air Agency). Levels of 60-90 micrograms per cubic meter are unhealthy of vulnerable populations.   Weakened solar radiation coupled with cooler temperatures also means that there is less drying of the soil.


According to the Canadian smoke forecast modeling system, we have several more days of this.  And meteorologists need to get the effects of smoke into our weather forecast models, something that is generally missing.

So should we thanks the Canadians for keeping us cool, or curse them for smoking us out?  I will leave that for you to decide.


____________

Announcement:  Atmospheric Sciences 101

I will be teaching Atmospheric Sciences 101 this fall if anyone is interested either as a UW student or the Access Program for those over 60.  This is a general intro to weather and weather prediction.  MTWTh 10:30-11:20, Kane Hall.  No remote access...sorry.

Monday, August 7, 2017

Rapid Worsening of Air Quality over Puget Sound Today

Air quality declined very rapidly today as temperatures rose back into the mid-80s.   Not only was the degradation obvious on air quality sensors, but visibility clearly worsened during the day.  To illustrate, here are two images from today (top) and yesterday (bottom) from the Seattle Panocam at 4:50 PM.  Much worse today.


Take a look at the small particulate measurements (PM2.5 concentrations) from some local reporting stations (graphic from Puget Sound Clean Air Agency).  Huge rise during the day today at Seattle, Tukwila, and Tacoma...with air quality today comparable to August 3/4.    Really nasty and unpleasant out, with a number of folks complaining to me about coughs and sore throats.


Why did the air quality get so bad today, something that several of us were forecasting two days ago?

 First, the low level winds over western WA switched from onshore (southwesterly and westerly) to northerly and northeasterly, thus bringing in the smoky air from the wildfires in BC.  The time/height cross section of winds/temperatures above Seattle illustrates this change.

Another major change was greater vertical mixing.  With less cool marine air near the surface, the inversion aloft, which acted as a barrier to the smoke aloft, was weaker and that allowed surface heating to mix the air in the vertical.   That is why the air quality declined during the day...vertical mixing was bringing down more and more smoky air.

Levels of PM2.5 particulates of 60-90 micrograms per cubic meter, what we saw this afternoon, are definitely unhealthy for vulnerable populations and ruin our typically great views of the water and mountains. Tomorrow should be more of the same.

Yesterdays smoke aloft really messed up the Blue Angels presentation, with the aircraft quickly disappearing into the muck as the rose vertically.  And when I flew into Sea Tac on Friday evening, the scene below was other worldy (see below).  




Dry Period Record Tied Today

There has been no measurable rain at Seattle-Tacoma Airport  for fifty-one days.   This ties the record for number of consecutive days without measurable rain, which occurred from July 7 to August 26, 1951.

And considering the current weather situation and the latest model forecasts, we are going to break the record tomorrow.    In fact, we are going to smash this record, with no rain in sight for the lowlands for the remainder of the week.

To illustrate our summer precipitation situation, here is a plot of the normal (blue line) and actual (purple line) precipitation at Sea-Tac for the last 12 weeks.   We had one very wet day in mid-June, but after that precipitation basically ended.
Now it can't be stressed enough that the summer are generally dry around here, and as shown by the figure, we are only about an inch below normal for the 12-week period.   So in terms of real impacts, the lack of summer precipitation doesn't mean that much, particularly after a very, very wet winter and spring.

Meteorologists like records though, and I am no exception.

Our temperatures this summer have been a few degrees above normal, as illustrated by this temperatures plot at Sea-Tac for the same period (average high is purple, average low in light blue)
And the deviation of the average max from normal for the last 60 days indicates that western WA is roughly 0 to 2 F above normal.   The West Coast has clearly been warmer than normal.

Why warmer and drier?    Because of persistent high pressure (ridging) over the West Coast,  which is demonstrated by the anomaly (difference from normal) of the heights of the 500 hPa pressure surface for the past 30 days:

OK, the big question folks are asking are asking is when this warm/smoky situation is going to end? 

 Well, I have good news for them.....the latest forecast ensembles suggest a shift to a cooler, wetter pattern over the weekend.    Here is the latest National Weather Service global ensemble forecasts (GEFS) for 2-m air temperature.  We actually warm up this week (sorry), followed by a distinct cool down on the 13th-15th.  Yes, uncertainty increases (the variability amount the ensemble forecasts), but all go for cooling.



Saturday, August 5, 2017

Improved Air Quality at Low Levels over Western Washington as Smoke Pours in Overhead: It Won't Last Long

The three dimensionality of the atmosphere over the Northwest is well-illustrated this morning, as cool, relatively clean marine air pushed into western Washington overnight, while smoke moved in overhead from fires in eastern WA and British Columbia.

The visible satellite image this morning says it all.  Low clouds cover the ocean, with some of them pushing inland to Olympia and through the Strait of Juan de Fuca.  Smoke covers eastern Washington and British Columbia and is pouring westward aloft over Northwest Washington and the Cascades.



To get an idea of the vast differences in local air quality (actually amounts of small particles in the air), here is plot from the wonderful Forest Service Airfire web site.  Green is good air quality, red is bad, and yellow is marginal.  Most of western Washington is now enjoying decent air quality near the surface due to the marine air intrusion last night.    Eastern Washington and BC are bad news.  On the right you can view plots at individual stations.  Big improvements in Seattle, Portland, and the coast.  Lots of smoke at Twisp and Ellensburg in eastern WA.


As I noted, the three dimensionality of the atmosphere is critical for understanding what is happening now.    Consider the winds and temperatures about Sea-Tac Airport over the past day (see below, time height cross section of winds and temperature, temps in °C, heights in pressure, 850 is about 5000 ft).   You can see shallow southwesterly winds bringing in cooler air (14C, 57F), while northeasterly/easterly winds are aloft.  We actually have an inversion right now above us, with temperatures warming with height until about 900 hPa (about 3000 ft)

The low level air is clean and cool, while the easterlies aloft are laden with smoke.   The smoke aloft is what is radically reducing the solar radiation reaching the surface and giving the sun's light a reddish color.  The smoke we are seeing is now partially domestic, with a major fire in the NE WA Cascades.

If you want to escape smoke, go south of Olympia or head to the coast.

Now the bad news.  Today is the good day for air quality around Puget Sound.  The onshore flow will weaken today and daytime mixing will bring the smoke down to the surface.  Tomorrow (Sunday), the winds will be more northerly, which will lessen the inland movement of clean Pacific air and bring more smoke down from BC.

Global Warming 

There are a number of folks that are claiming that this smoky/warm period is a sign of global warming.   I believe that many of them are seriously stretching the facts and trying to simplify a complex situation.  I will blog about this issue during the coming week, but consider the following:

1.   Most forest management experts agree that the major issue is the past mismanagement of our forests.   This includes suppressing natural fires, leaving slash and dead material on the forest floors, changing the density of the east-side forests, and much more.   Some global warming activists are happy to ignore this.
2.  Wildfire is a natural part of healthy forests in our region.
3.  The replacement of natural grasses by fire-prone foreign species has greatly increased grass fires.

4.  Increasing human pressure and fire initiation (fireworks, campfires, arson) has enhanced fires.
5.  The meteorological situation of this event is not one of uniform warming, but localized warming during the last month due to anomalous high pressure over our region.  The weather has been COOLER THAN NORMAL over the the high plains.  There is NO reason to expect more high pressure in the future under global warming.

Human-induced global warming has warmed the region about 1F so far, which is MUCH less than the 15-20F temperature anomalies associated with this event.

More later.


Friday, August 4, 2017

Smoke Starts to Recede as Marine Air Pushes into Western Washington

A weak inland push of marine air occurred this morning, resulting in dramatic improvements of air quality along the coast, in the Strait of Juan de Fuca and over the south Sound.   On the other hand, some locations over NE Washington have worsened smoke, as local fires have added to the plumes from British Columbia.  Seattle, located in the dead zone behind the Olympics, has not enjoyed much improvement yet...but the smoke will slowly lessen during the next day.

The NASA MODIS satellite imagery shows low clouds along the coast, with some tendrils moving inland through the coastal mountains.   Western Oregon and SW Washington are less smoky, but some smoke is still evident over Puget Sound.  Dense smoke is found over NE WA from a combination of the smoke from BC and local fires (e.g., the Diamond Creek fire).  Very bad over Bellingham and Vancouver.

 Compare today's MODIS image to yesterday's at the same time (around 1 PM).
More smoke over the offshore waters and SW Washington.  Better over NE WA.

Air quality has improved at several locations, but gotten worse at others. Here is the data, showing  a plot of the concentration of small particles (PM2.5).  Seattle (blue) is slightly better, but Aberdeen, Mount Vernon, and Cheeka Peak (NW tip of the Olympics) are almost back to normal.  In contrast, Twisp--in the eastern foothills of the North Cascades--is a disaster, with a huge spike in particles.


A solar radiation measuring device near Twisp indicated a LOSS of 70% of the normal radiation from the sun.  Unbelievable.

Improvement in western Washington is occurring as the thermal trough jumped into eastern WA and an onshore pressure gradient has developed, in turn forcing onshore winds.  You can see this trend from the winds above Seattle (see time0/eight cross section below, time on x axis, height in y).  Both winds (barbs) and temperature--red lines--are shown.  The strong northerly winds of the past few days are gone (which blew in the smoke), but the winds are too light to really mix out our smoky surface layer.

The forecasts model for tomorrow show a continuation of weak onshore flow...this will bring down temperatures (into the upper 80s, but still way above normal), but not enough to clean out the lower atmosphere of western WA.


We are simply not going to cool down much over the weekend.  The reason...an amazingly persistent ridge of high pressure over the West Coast (see map for Saturday afternoon at 500 hPa).  And folks, there is little doubt we are going to break the big record for consecutive dry days (51).



Wednesday, August 2, 2017

SMOKEZILLA Versus the Heat Wave

Today was one of the smokiest days ever in western Washington as the surge of smoke from the fires in British Columbia continued to push southward.  The dense smoke, a.k.a. SMOKEZILLA, was thick enough to appreciably reduce the amount of solar radiation reaching the surface and resulted in cooler temperatures than forecast.   Seattle only hit 91F and Portland topped out at 103F, both locations 3-5F cooler than expected.

SMOKEZILLA was impressive in today's satellite imagery.  The visible satellite imagery at 8 AM, was stunning, with smoke spreading across the lowlands and coastal zone.


The MODIS image around 1 PM shows amazingly dense smoke over NW Washington, with smoke around the entire region, including a plume headed out into the Pacific.


A colleague of mine, Gary Lackmann of NC State, took this picture today from his plane leaving Sea Tac....smoke nearly to the top of Rainier!

Air quality was unhealthy for much of western Washington and a burn ban is in place.  The concentrations of particulates surged higher than yesterday, with locations such as Neah Bay's Cheeka Peak getting to Beijing levels.


What really impressed me was the reduction in solar radiation by the smoke.  Comparing the radiation received today against two days ago, revealed a drop of 11-14% in intensity.  As a result, the high temperatures were clearly suppressed by 3-5F.  Seattle-Tacoma Airport "only" reached 91F, when 95F was expected.  Portland peaked at 103F, when 107-108F was predicted. 

So SMOKEZILLA clearly took the edge off the heat-wave monster.  His (or her) services will be needed tomorrow, which should be the warmest of the sequence in Seattle (around 94F).  But there is a downside to the smoke monster....it could well keep the temperatures up overnight (Wed to Thursday) since it will slow the loss of infrared energy to space from the surface.

And did I mention that Quillayute on the northwest Olympic Peninsula coast got to 99F, tying the ALL TIME RECORD HIGH FOR ANY DATE.  And  that was with smoke.

And believe it or not, air quality was MUCH better in Beijing today than in Seattle...here is proof: