Labor day, a holiday up in smoke

I have been working on blog posts, but it seems like we have been getting smoke more often than I can find time to write about it! However, yesterday's smoke was the worst that we've had all summer, so I felt compelled to sit down and write out the post. Warning, this is a pretty long post. We had a whole holiday weekend full of smoke, with concentrations hitting 30 and 40 ug/m³ on Saturday and Sunday, and it all seemed to stick around and build up overnight on Sunday.

When I woke up Monday morning, it was so dark and hazy. I checked the PM_2.5 concentrations, and I was pretty surprised how high the concentrations were for not having a fire nearby. Concentrations were over 100 ug/m³ overnight (shown in time series below)! In the following plot, I am showing you a longer time series than I usual do, so that you can see normal summertime concentrations (August 24/25), the slightly smoky days like we've been seeing a lot of this summer (August 29-31), and then this event from the past weekend.

Time series of PM_2.5 concentrations measured in Fort Collins (blue) and Greeley (orange) for August 22 through September 5, 2017 (dashed lines indicate start of new day). Data from https://www.colorado.gov/airquality/. 

I went out and took the following pictures in my neighborhood in Laporte.

Looking east (left) and west (right) from Laporte at 7:45 AM on September 4, 2017.

The CDPHE released this advisory Monday morning:

Air Quality Health Advisory for Wildfire Smoke

Issued for areas below 7000 ft. in eastern ColoradoIssued at 9:30 AM MDT, Monday, September 4, 2017 

Issued by the Colorado Department of Public Health and Environment 

Affected Area:  Areas below 7000 ft. in eastern Colorado.  Locations include, but are not limited to Denver, Boulder, Ft. Collins, Greeley, Colorado Springs, Pueblo, Ft Morgan, Sterling, Julesburg, Holyoke, Boulder, Broomfield, Brighton, Littleton, Akron, Wray, Castle Rock, Kiowa, Hugo, Burlington, Cheyenne Wells, Ordway, Eads, La Junta, Las Animas, Lamar, Trinidad and Springfield.

Advisory in Effect: 9:30 AM MDT, Monday, September 4, 2017 to 9:00 AM MDT, Tuesday, September 5, 2017

Public Health Recommendations: If smoke is thick or becomes thick in your neighborhood you may want to remain indoors.  This is especially true for those with heart disease, respiratory illnesses, the very young, and the elderly.  Consider limiting outdoor activity when moderate to heavy smoke is present.  Consider relocating temporarily if smoke is present indoors and is making you ill.  If visibility is less than 5 miles in smoke in your neighborhood, smoke has reached levels that are unhealthy.

Outlook:  Moderate to heavy smoke from fires in the northwestern US and western Canada is being transported into eastern Colorado.  Smoke will slowly decrease Monday afternoon and evening, however due to the lingering health impacts of fine particulate concentrations we urge the public to continue to follow the health recommendations listed above through at least Tuesday morning.

My co-workers and I started trying to figure out where the smoke was originating. The HMS fire product showed that there was a fire west of Fort Collins near Walden, CO, but the satellite images seemed to show this smoke was coming from the north.

HMS smoke and fire products for 4 September 2017 in the AM (left) and PM (right).

You can really see all the smoke from Idaho and Montana in this image from the GOES-16 satellite released by the NWS. We were all looking at the GOES-16 loops and were pretty mesmerizedd by the smoke transport (you can look at the latest ones here: http://whirlwind.aos.wisc.edu/~wxp/goes16/vis_color_enh/goes16_conus_3h.html).

We had planned to go to Horsetooth Reservoir, but when we got there, it was pretty smoky as shown in the following pictures (comparing June 4, 2017 to August 4, 2017). We only lasted about 45 minutes before our eyes were itchy, and our throats were scratchy.

Looking south/southeast from North Bay at Horsetooth Reservoir on June 4, 2017 (left) and September 4, 2017 (right).

From the advisory, you can note that many areas of the state were impacted by the smoke. I plotted up concentrations from two of the monitoring stations in Denver, there's a pretty similar pattern to the concentrations measured in Fort Collins and Greeley. However, concentrations did not get as high, and the timing of the peak concentration in the afternoon was a couple hours later.

Time series of PM_2.5 concentrations measured at two Denver sites: La Casa (blue) and CAMP (orange) for August 22 through September 5, 2017 (dashed lines indicate start of new day). Data from https://www.colorado.gov/airquality/. 

These are images of Denver comparing September 4th (at 4 PM) of 2016 to 2017. Pretty big difference!

Image of Denver at 4 PM on September 4th 2016 (left) and 2017 (right). From https://www.colorado.gov/airquality/live_image.aspx.

Thankfully, concentrations went down today. They are still above "normal" (as you can see from the time series above) but now that we are back sitting in the office, the air outside is much better for outdoor activities. Hope you found some good indoor activities yesterday!