Monday, July 13, 2020

Is Air Conditioning Contributing to Coronavirus Spread?

The headlines are screaming about recent increases in coronavirus cases, with some suggesting that the essential problem is the loosening of the lockdowns and restrictions.  A number of media sources note that many of the problematic locations are "red" states with Republican leadership. 

It is not surprising that moving out of lockdown resulted in more COVID-19 cases.  In addition, the increasing number of tests undoubtedly increases the number of known infected.

But could there be something else going on?

Could increased use of air conditioning, particularly in the southern tier of states, be a significant driver of increasing number of COVID-19 cases?

This blog will attempt to help answer this question.

So where is the virus really spreading?   A good way to see the problem locations is to view the percentage of positive tests.  A worsening epidemic is signaled by a higher percentage of positives, assuming there is widespread testing.  Positive percentage is far better than number of positive tests, which, of course, varies by the amount of testing.

Here is a plot of the positive percentage on July 7th.  The big problem states were Arizona, followed Mississippi, Florida, South Carolina, Texas, Georgia, Alabama, Nevada, and finally Idaho.

Below is a different type of plot that shows the same thing, but provides the actual numerical values.  The bottom line:  the situation is far worse for states along the southern tier of the U.S.  Arizona is the worst, with Mississippi and Florida right behind.  These are states with very different demographics.

But what do these states have in common?  Some media outlets are pushing the fact that most of these states are dominated by the Republican party and have been quicker to open up.  But they have something else in common:  these states have had high temperatures with a lot of air conditioning use.  (And no, there is no reason to think that heat turns people into Republicans).

If we look at the high temperatures in June (shown below, NOAA division dataset), southern Arizona (including Tucson) is the nation's hot spot--and yes, it is the hot spot for COVID-19 as well.    Mississippi, South Caroline, Florida, Texas are all very hot.  And according to U.S. Census data nearly all homes and most restaurants in these states have AC.

And an independent graphic, showing the high temperatures averaged over the 30 days ending July 7th (Climate Prediction Center), has a similar pattern.  Arizona has the highest temperatures.

So let us consider a hypothesis: the rapid warming in late spring led to greatly increased use of air conditioning in homes, stores and restaurants in the warm, southern tier states.   More people are thrust into interior spaces with recycled, recirculating air that increases COVID-19 spread, something described in several research papers.  And the cooler, drier conditions associated with air conditioned spaces are favorable for COVID-19, and the blowing air spreading COVID-19 containing droplets and aerosols.

Now is this hypothesis consistent with observations?     We can begin by looking at the total tests and percent of positive tests in Arizona (see below).   Tests went up substantially in May and June, but so did the percentage of positive tests, which has progressively risen since mid-May (the largest increase was in mid-June)

So what happened in Tucson, located in southern Arizona during June?    Temperatures exceeded 100F on many days and over half of the month was above normal (green shows the normal range).   Some days were way above normal.  June is the worst month in southern Arizona--very, very hot without the relief of the southwest monsoon in July.  Air conditioning was a necessity and this miserable period is exactly when the virus surged.

Florida had a similar story.  Positive percentages surged in middle and late June.

And this is exactly when temperatures surged to way  above normal in southern Florida (see below). And Florida has terrible humidity as well.  Folks were forced to flock to air conditioned spaces.

You want something more rigorous?  No problem.

If I was writing a paper on this topic, I would present a scatter diagram plotting the temperatures against positive percentages of COVID-10.  And I have done exactly that below.  Specifically, I found the June average maximum temperature for every state in the continental U.S. and its corresponding positive percentage for COVID-19 (Y-axis percentage, X-axis is average high temperature).  Each state is shown by a blue dot.  I only plotted states with max temperatures in June of 75F or more, which excluded a handful of states that are very cool and have very few air conditioners (e.g., WA, OR, and Montana).

I also plotted a best-fit line (red).   There DOES appear to be a relationship between COVID-19 infection rates and temperature.  The correlation coefficient is .69, which suggests this relationship explains about 48% of the variability.   That is quite a bit.  The point in the upper right corner?--Arizona.

Now certainly there are a number of factors that help explain the variability of COVID-19 infection rates around the U.S.     But I do think the above results are very, very suggestive that very warm temperatures result in increasing infection rate.  Not because the virus likes warm temperatures (it does not, as shown by a number of studies), but because warm temperatures push people indoors into air conditioned spaces in which spread is greatly enhanced.  Restaurants and bars are probably key here.

In warmer climates, summer is the time when folks huddle together in confined spaces and thus the greatest potential for COVID spread.  The implication of all this is that the situation might be expected to worsen over the southern tier states and into the warm/humid areas of the southeast over the next month or so, but improve during the fall.  Clearly, there is reason to avoid air conditioned interior spaces during a COVID epidemic, and dining should mainly limited to outdoor spaces, which should be quite safe.

Saturday, July 11, 2020

Watching Comet Neowise at 3:30 AM

I got up at 3 AM this morning to view COMET Neowise.   The COMET had passed the sun on July 3, getting as close as 27 million miles, and is now moving back out into the solar system.  Its orbital period, the time to complete a loop from near the sun to location far beyond the planets, is 6800 years.  So you better catch it this time.

It was not a little strange walking the streets to find a vantage point at 3:15 AM.   Some animals shuffled in the bushes and amazingly, there was some light on the northern horizon.   There is only about 2.5 hours of real night this time of the year and astronomical twilight had already begun when I was out there.   Extraordinarily, some folks were shooting off fireworks at the time and I could hear loud shouting in the distance. Perhaps their deep joy in seeing the comet.

When I climbed to a good perch to view the northeast horizon, I was able to see Neowise----faint, but clearly visible.  Here is a shot from my smartphone.

But if one wants a good picture of something in the sky, it often wise to first check with Greg Johnson of Skunk Bay Weather, who has a high quality camera surveilling the sky each night.  He captured the event nicely--check out his video (below).   You will see the comet rising, starting about 10 seconds in.  And at one point, the comet crosses a contrail from a high-flying jet.

A worry this morning was the high cirrus from an approaching weather will rain tonight.  Fortunately, the cirrus was thin enough, and the COMET bright enough, that one could see Neowise.

For those who don't like getting up at 3 AM, soon the COMET will be viewable after sunset.  And the COMET will be getting closer to us, being nearest on July 23rd (64 million miles!).   Unfortunately, moving away from the sun, the COMET will probably dim.   Hopefully, it will still be visible. 6800 years is a long time to wait.


If any reader is a Google employee and works on GoogleEarth, please contact me.  I need help in getting permission to use some images in the second edition of my Northwest Weather Book.

Wednesday, July 8, 2020

A Cold Start for the Summer Season

OK....we need a new name.



Whatever the name, the last week has been mainly cloudy and well below normal in our area.

According the maximum temperature anomaly map (difference from normal ) for Washington for the first seven days of July, the high temperatures in most of western Washington have been 6-12F below normal.    Even eastern WA has been generally cool.

At SeaTac Airport, not a single day had the high temperature reached the normal values (low to mid-70s)--see below.

Sunshine?     Much less than normal!  To illustrate, here is the solar radiation observed at the WSU AgWeather site in Seattle. We should be hitting a peak of about 950 this time of the year, but many days have been warmed by half or less (like yesterday and June 27th).   Just depressing.

Normally, our region dries out rapidly after July 4th, with lots of sun each day.  Not this year.  Tomorrow?  Don't get your hopes up.  Another wet weather system is now approaching and the latest forecast of 24-h precipitation ending 5 PM tomorrow (Thursday) has a good wetting from the WA coast, NW Washington, and southern BC.  Not many wildfires this year so far.

And do I dare show you the National Weather Service OFFICIAL 6-10 day temperature forecast?
Are you strong? Here it (cooler than normal) over our part of the U.S.

Can we depend on the BLOB, that area of warm water off our coast to provide a warm solace?  Unfortunately not....the temperatures are near normal off our coast, with some areas even below normal.

What is the cause of this cool, cloudy affliction?   We have been stuck in a pattern with higher than normal pressure offshore, but lower than normal pressure over the Northwest, resulting in enhanced onshore flow of cool, cloudy marine air.   The pressure anomaly for June 25-July 1 below illustrates the problem (purple is below normal pressure, red is above normal).

I notice that there is a movie about our situation (see below).  With a guy with a gun, this does not sound like it is a flick with a happy ending.

Monday, July 6, 2020

The Jury is In: Personal Fireworks Alone Can Cause Dangerous Air Pollution

This July Fourth we answered an important question:  if most U.S. community fireworks displays are cancelled (because of COVID-19) might July 4th air quality be substantially improved?

We now know the answer:  air quality was very poor the evening of July 4th and the immediate morning hours, in some locations as bad or worse than previous years.  Personal fireworks are clearly the mainstay of the air quality disaster of July 4th.

Let me prove this to you.  Consider an image that will shock and awe...but in a bad way... showing the EPA Air Quality Index (AQI) at 4:30 AM Sunday (July 5) morning (PDT).  Just scary.  The U.S. really stands out with reds and even purples--from unhealthy to hazardous (the EPA AQI scale is shown below).  Some of the worst air quality in the world.  Very bad for folks with asthma and respiratory/heart issues.

AQI Map Courtesy of

Now, let's zoom into the U.S. for the same time.  The West Coast is particularly bad, with some locations getting into the hazardous zone (301 or more on the AQ scale).  No issues in Canada.

Some areas in Los Angeles were crazy bad, with several locations getting above 400.  Such values will make even healthy people feel unwell.  Such levels can be sickening in vulnerable people.

Moving to Puget Sound at 4:15 AM, unhealthy conditions (red and darker) were widespread, but not as bad as LA.

And turning to a summary for the Seattle metro region, one can view the extraordinary degradation to hazardous level that occurred after 10 PM July 4th.

No wonder sunrise this morning in Seattle brought a smoky haze, as viewed by the Seattle PanoCam.
Not a morning to take a deep breath.

An important issue is how this year, without big community events, compares to last year, when the usual community fireworks displays were taking place.  

Consider the Puget Sound Clean Air Agency site in South Park (south Seattle).  Below are plots of concentrations of PM2.5--small particles that can move deep into your lungs--for this year and last.  The values last year got to roughly 102 (micrograms per cubic meter of hour, one-hour average values.   Clearly in the unhealthy range.
This year?  It went even higher... around 120.
This comparison was no outlier.  2020 was worse than 2019 at many locations.

Thus, a reasonable conclusion is that personal fireworks and other home-based activities (like barbecuing) are a far more important source of July Fourth air pollution than the community displays.

Why was this year worse than last?  The meteorology was favorable, but perhaps more important was that personal firework usage were up--at least the media were reporting this.    And the personal fireworks bought at local "boom cities" appears to be larger and higher flying than in the past.  Certainly, at my location in north Seattle the explosive concussions were the worst I have experienced and the rockets going up from Mathews Beach park were extraordinary--some almost professional level.  My little dog was terrorized.

A question that is often asked is why don't Seattle Police enforce the fireworks ban in the city on July 4th?  Air quality declines to very unhealthy levels, animals are scared, homes and apartments are set afire (like the apartment complex in Tacoma), and kids are getting hurt.  Maybe this is an issue for which we need more police, not less.

Saturday, July 4, 2020

Weather Forecasting is Fifty Years Ahead of Epidemiological Prediction: That Must Change

In October 2012, Hurricane Sandy approached New York from off the Atlantic.  Seven days before, a near perfect track forecast was made by the European Center and two days later the U.S. model (the GFS), run by the National Weather Service's Environmental Modeling Center, has locked on as well.

The stunningly accurate prediction of an extremely unusual event, saved countless lives, with only about 100 deaths in a region of tens of millions of people (and most who died made a bad decision to ignore the forecast).

Although a hurricane hitting New York is exceedingly rare, the excellent forecast was based on an extraordinarily weather prediction infrastructure that had been perfected over the past half century, with sustained investment and development:
  •  A comprehensive observing system, based on weather satellites, surface observations, and more.
  • A complex quality control and data assimilation system the ensured a good idea of what happening in real time.
  • Highly complex numerical models for simulating the evolution of the atmosphere, models that had been tested and perfected over decades.  And a dedicated U.S. forecasting center responsibly for state-of-science prediction.
  • A mature statistical postprocessing system capable of improving the model forecasts based on past performance.
  • A comprehensive verification system to provide detailed evaluations of the skill of the forecast.
  • A highly developed communication system, that provided the public with clear interpretation of the forecast.
Excellence in prediction took time and investment over decades, and paid off in warning the public and guiding public officials in protecting the population.
Stunningly, U.S. epidemiological modeling has almost NONE of the above components or systems, and the performance of the U.S. Centers for Disease Control and Prevention (CDC) as poor.    Consider:
  • There is no large, permanent epidemiological prediction center in the U.S. government analogous to the NOAA/NWS.   U.S. response to COVID had to depend on a hodgepodge of university forecasting efforts, some spun up for this event.  Untested, unverified, and often very wrong.
  • Unlike weather prediction, U.S. epidemiologists do not have an accurate description of what is happening NOW.  Testing was slow to begin, in fact, the CDC made serious errors in test development.  Even today, six months into the pandemic there are not enough tests.  There is no attempt being made to randomly sample the population to understand how many folks have or were infected.  Unbelievable.
  • Unlike the comprehensive and smoothly running weather observational system, there is poor organization to the data collection by CDC. There are not even standard reporting approaches.
  • The epidemiological models are generally primitive affairs, many of which do not consider the complex, variable transmission properties of a heterogeneous population, and lack clear information of what is occurring right now (called the initialization in weather prediction).
  • Communication by CDC of both the threat and how to deal with the disease has been inconsistent and often wrong.  For example, they initially discouraged the use of masks, before reversing their guidance 180 degrees.  Similarly, CDC downplayed the threat in January and February, before reserving in March.  The NWS works very hard to start with reliable forecasts, to communicate the uncertainties, and not to go back and forth in their warnings.  They are masters at this.

So let us imagine what the Hurricane Sandy forecast would have been like if the NWS followed the CDC approach.
  • The storm would have been out there, but without comprehensive observational assets, they would not have known where it was.
  • Without a government prediction organization, the NWS would have asked for volunteer forecasts of University modeling research groups (like the University of Washington).  They would have had 5-10 forecast from various universities that would have diverged by position and intensity.  Without good initialization data, none of the forecasts were skillful.  And furthermore, without long-term verification, no one knew how good the forecasts were.
  • Based on this guidance, the NWS could not provide specific, accurate forecasts, suggesting that there was a storm out there, but it could hit anywhere from Georgia to Maine, or might go out to sea.
  • With such uncertain forecasts, political leaders pressured to evacuate the entire coast from Georgia to Maine at a huge cost.  Many would not evacuate under such vague warnings. With landfall on NY and many remaining in their homes, nearly 4,500 people died

The Political Opportunists

        There are some folks and many media pundits who are claiming this COVID disaster is all the fault of President Trump and that things would have been much better under a Democratic President.

This is either very naive or very cynical.

There is no doubt that the President and his administration has been startlingly misinformed and ineffective. His abysmal leadership has made things much worse.

But the problems noted above are not recent developments and have been allowed to fester in recent administrations, including the 8-years of President Obama.  I suspect we would not have been in much better place if Hilary Clinton would have won, because the basic institutional infrastructure was not put in place.

That is what we must do together as a nation, following the example of the weather prediction community.  And speaking as one of them, we would be glad to help.

Thursday, July 2, 2020

A Dark Month for Seattle

There have a lot of complaints about our cloudy weather of the past month--and it has been a bit depressing.

Yes, western Washington typically "enjoys" a cloudy, June gloom this time of the year, as high pressure builds over the eastern Pacific, pushing cloudy marine air up to the Cascade crest.

June 29th

Has this year been particularly bad?  The essential answer: Yes, but not by a lot.

We can start with the total monthly radiation reaching the ground in Seattle at the WSU AgWeather site near the UW, which only goes back to 2012.  June 2020 was the darkest June since 2012--eight years.  June 2015, when high pressure dominated our region, was far brighter.  2012 was abysmal.

Looking at the daily solar radiation numbers in Seattle, one notes some variation in the sunshine reaching the surface, with some decent amounts in mid-month.  But the first half of June and the last week have been cloudy and dark.

Accompanying the enhanced clouds was more rain than normal, something evident at Sea-Tac Airport, where there was about an inch more than normal over the past 4 weeks (see below, cyan is normal, purple is what fell into the gauge there).
Why so cloudy and dark in June?  Blame enhanced high pressure over the eastern Pacific and lower pressure inland.  But this year, the pattern was supercharged.  Let me show you.

Here is the difference from normal of the heights (think pressure) at around 18,000 ft (500 hPa).  Heights were much higher than normal (yellow/orange colors) over the eastern Pacific, but lower than normal (blue colors) over Montana, Idaho and eastern WA/OR.    Such a pattern is associated with higher than normal sea level pressure over the Pacific, lower than normal pressure to the east of the Cascades, and an enhanced onshore pressure difference that pushes cloudy, marine air into western Washington.

The result is day after day we had satellite pictures that looked like this.

Sunny in much as eastern WA, but dark in the west.

Looking forward I have some good news and bad news.  The good news is that there should be more sun over the weekend as the above infernal pattern weakens.  Bad news, because the pattern is forecast to return next week, with lots of low clouds again invading the west (see forecast for 5 AM Wednesday below).

Tuesday, June 30, 2020

The Safety of Outdoor Air for Coronavirus Is Now Obvious

There is now powerful observational evidence that outdoor air is extraordinary safe regarding COVID-19, and the recent protests have helped provide it.   The protests/riots began in Seattle and other cities on May 26th.  Thousands gathered without social distancing and a good 10% had no masks.  They participated in chanting, singing, screaming and other activities that ensured plenty of droplets were injected in the air, and that unhealthful environment was "enhanced" by coughing from tear gas and other agents.

Did this huge exposure result in increased spread of COVID-19?  The answer is clearly no.

Consider Washington's King County, a hotbed of protests starting 26 May (see below).  Both hospitalizations and deaths showed no  upward spike after the protests (the blue line shows May 26th).  We should have seen a signal by now, since the average time to symptoms is approximately five days.

It is important to note that the number of COVID-19 cases is going up modestly in King County, but that is being driven by a near doubling of tests (note that the bottom graph starts earlier).  Much of the media neglects to note the importance of increased testing in finding more cases.

This lack of a coronavirus spike has been noted in every major city in the U.S., something discussed in the Seattle Times today and in many media outlets.

These are huge number of independent experiments in varying environments and climates.  A very good sample. And the obvious conclusion is that COVID-19 has a very difficult time spreading in outdoor air.  There is no other explanation.

Some of you might argue that many of the protestors were young and so would not get very ill.  True enough.  But young people can get sick from it and they could certainly give it to their parents, neighbors, and folks in food stores and restaurants.  There were plenty of teenagers and folks in their early 20s still living at home who were at the protests.

You want more evidence?  No problem. About a month ago, there was a huge media commotion about "irresponsible" outdoor parties at Missouri's Lake of the Ozarks (see picture below from the famous "party cove".  Several media outlets promised a huge uptick in COVID-19 cases.

What actually happened?  Nothing.  No spike of COVID-19 cases in the neighboring counties.  Outdoor air is safe.


The lack of outdoor transmission is consistent with the scientific literature.  There is in fact no documentation of effective outdoor transmission of coronavirus (see my earlier blog for documentation).    Some examples of scientific papers discussing the issue, include:

Qian et al., 2020:   Examined 1245 confirmed cases in 120 cities in China and identified only a single outbreak in an outdoor environment, which involved two cases. 

Nishiura et al., 2020:  Transmission of COVID-19 in a closed environment was 18.7 times greater compared to an open-air environment (95% confidence interval).

The reasons for a lack of outdoor transmission are clear:

  • Virus concentration are low outdoors because of the tremendous dispersion of the virus in the outside environment.  This results in low viral concentration.  
  • Solar radiation rapidly kills the virus.
  • Higher humidity in the outside air is bad for transmission.
  • Social distancing is much easier outside.

We have folks going outside with great fear, even wearing masks when they are alone or distant from others.

The other day I was biking down the Burke Gilman trail and an older women saw me coming and fled off the trail, pushing her mask tight around her mouth as she turned to face away from me.  There was profound fear in her eyes and it was completely unnecessary.  Really bothered me.

And such fear is being stoked by local politicians and governments.  The City of Seattle parks STILL has many of the parking lots closed and threatening signs everything.

Completely inconsistent with scientific evidence and even the Mayor's Office's own statement on the lack of transmission during the protests.  Talk about being anti-science and irrational.

Take a look at the welcome provide by Seattle Parks and Recreation for Magnuson Park, one of the city's jewels.  Why does the Mayor allow this situation to continue?  City parks should be completely opened.


Additional Material

One commenter noted that percentage of positive test are increasing recently, indicating viral spread.  This is true.  But as shown by the plots of positive percentiles for Washington State (and daily tests), the rate of positives fell for WEEKS after the protests (which started at the time of the blue line).  The minimum was in mid-June.  The positive percentage is a very fast reacting measure of increase of COVID-19 transmission and there is NO hint of a surge with the advent of the protests.  More recent rises, in WA and for most of the country, are associated with lessening of restrictions and lockdowns.

PS:  Wearing masks is a very, very good thing if you are indoors.   More than a good thing-- necessary in all public indoor spaces.