Numerous wildfires began to increase in size and intensity from northern Minnesota to central Canada in mid-July 2026, as previously discussed on this blog (13 July | 14 July | 15 July). A large scale view of the GOES-19 (GOES-East) Aerosol Optical Depth (AOD) derived product on 15 July (above) displayed the long-range transport of this wildfire smoke across parts of the central/eastern Lower 48 states and the western Atlantic Ocean. The southernmost plume of high AOD was being recirculated inland from the Atlantic. Surface weather symbols of smoke or haze indicated that some of this smoke was reaching the ground (and adversely affecting visibility and air quality).

Even though the Aerosol Optical Depth derived product has a default AWIPS color table range from 0 to 1, the actual sampled AOD values associated with particularly dense smoke were as high as 3.22 over central New York (below).

Gaps in the AOD were due to the Cloud Mask product preventing AOD creation where thick clouds were present — so simply looking at GOES-19 Visible imagery (below) perhaps offered a smoother depiction of the hazy smoke transport.

GOES-19 True Color RGB images (below) provided the best qualitative view of the wildfire smoke transport.

The GOES-19 imagery shown in this blog post ended at 2021 UTC — shortly thereafter, the satellite suffered an anomaly, and went into “safehold” mode while NOAA/NESDIS engineers worked to diagnose the problem.

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Friend of the Blog Patrick Ayd, Science Operations Officer at NWS Duluth, passed on this interesting observation from the morning of 15 July 2026. The ongoing wildfires in Minnesota and Ontario, which we discussed in a blog post a few days ago, show up amazingly well when looking at the VIIRS Day/Night Band (DNB). The view below shows a string of brilliant blotches stretching across the middle of the image. Compare these bright spots to the city lights of metro Winnipeg (center of the left edge), Fargo (lower-left corner) or Duluth (western tip of Lake Superior). These are clearly some very large areas aflame.

To further convince ourselves that these are fires, let’s do a quick comparison to the 3.9 micron channel from the GOES-19 (GOES East) Advanced Baseline Imager. We use that latter channel for fire detection due to its extreme sensitivity to hot spots. Below is a slider that allows you to toggle back and forth between the low-earth orbiting VIIRS and the GOES ABI images. The dark spots indicate where active fires are, while the most intense fires have colors associated with them. You can see how the 3.9 micron fire spots line up perfectly with the bright spots in the middle of the DNB image, but the bright spots associated with the cities have no counterpart in the 3.9 micron imagery. In fact, you can even see an advantage of the VIIRS view: there are some locations right on the US/Canada border where smoke or clouds are obscuring the thermal signal of the fire but the visible brightness still shines through. The moon phase was new at this time and therefore was not illuminating the clouds.

As a bonus, here’s an animation for the GOES Fire Temperature RGB showing just how widespread (and hot!) these fires are. This product is available from SSEC’s Real Earth.

Starting now and continuing over the next few days, the smoke from these fires is going to impact large swaths of the continental United States. Stay tuned to the CIMSS Satellite Blog for more on that topic. Thanks, Patrick, for bringing this interesting satellite view to our attention!

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Much of the time when we look at weather satellites, we’re using them to look at clouds: where are they, how fast are they moving, are they growing or dissipating, things like that. Right now, however, the dominant story across much of the continental United States is a persistent heat wave. In the past couple of days, several locations in the western US have broken their all time high temperature records, with multiple sites in Montana reporting temperatures in excess of 110 F (43 C).

Heat waves, of course, are often typified by a lack of clouds. After all, if there are clouds present, some of the sun’s incoming shortwave radiation is bounced back to space where it can’t heat the surface. Therefore, you might not think that satellites have a lot to see when you’re in the middle of a heat wave. However, there’s still much that our constellation of satellites can do to help diagnose what’s currently happening and how people are being affected by it.

First, let’s get a big picture view of southern Canada and the continental United States on the afternoon of 14 July 2026, as depicted by the True Color product from GOES-19 (GOES East). There’s lots to see here. Most of the central part of the US is clear except for further south, where Gulf-influenced dew points are sufficiently high to support the development of cumulus clouds; those will most likely dissipate as solar heating diminishes later in the day. Numerous fires in Ontario, Saskatchewan, and elsewhere are producing smoke that is joining with the output of Minnesota’s fires (which we discussed in a blog post yesterday). This smoke is forecasted to A large low pressure system east of Hudson Bay is drawing in flow to the northeast of this loop. We also see strong southerly flow over the western United States that takes a sharp turn to the east along the US/Canada border.

Of course, there’s also lots to see when you look at the infrared wavelengths, too. Here’s the Band 9 (6.9 micron) loop for the same scene. Now we start to see some interesting things. First off, we have a good view of the general upper level flow that clearly shows warm, moist Pacific ocean air from off the coast of California being advected northward into the Pacific Northwest and western provinces of Canada. We also see a strong plume of moisture penetrating the central US from the southeast, likely contributing to the development of the cumulus clouds we saw above. Much of the Great Plains appears dry, too.

It’s that ability to quickly identify the characteristics of the large scale flow that really makes a product like the water vapor loop useful on a day like today. This is especially true for the current observational environment in the United States, where many of the 1200 UTC radiosondes have disappeared from the central and western part of the country. Consider the 500 mb analysis from this morning. This chart is one of the most common tools that a forecaster uses for assessing the general state of the atmosphere and what the overall flow is going to be. And yet, there’s hardly any observations on the west side of this figure which really limits how much it can be trusted. The water vapor satellite loops help forecasters identify how the flow is behaving in the absence of the observations and fill in the gaps created by the change in radiosonde observation times.

Of course, we can also use the satellites to track the temperature of the surface itself. The MODIS land surface temperature product provides a global land surface temperature for both the daytime and nighttime overpasses. This image shows that the far western parts of South Dakota and northeastern Wyoming are approaching temperatures of around 116 F (47 C)! You can access this product at the NASA Worldview website, an excellent one-stop shop for polar orbiting level 2 products.

Of course, the standard Band 13 infrared can also tell us a good deal about how surface temperatures are distributed. Here’s a loop of that band displayed in AWIPS with surface weather conditions displayed. This is an alternative color scale designed to exploit the temperature characteristics and to lnot look so much like clouds. Note something interesting here: Iowa is further south than Minnesota, but the Land of 10,000 Lakes is actually a little warmer than the Hawkeye State. Some potential reasons for this: Iowa had some pop-up cumulus to help bring some intermittent relief from the sun, and the smoke from the Canadian fires has wrapped around and is infiltrating Iowa from the east while leaving Minnesota clear. Take another look at the water vapor loop to see the kind of flow pattern that can lead to such a result.

Despite the fact that much of the central United States is experiencing clear skies, there’s still lots to see from satellites. They’re an important part of understanding the weather, regardless of what type of weather there is.

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1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible images with an overlay of the Fire Mask derived product (above) showed the smoke plumes and thermal signatures associated with numerous wildfires across far northeastern Minnesota and southern Ontario on 13 July 2026. An elevated fire risk was in place, due to very warm surface air temperatures (near to above 100 F), low relative humidity and winds occasionally gusting over 20 mph. With the recent trend of increasing wildfire activity across the immediate area, a decision was made to close all entrances to the Boundary Waters Canoe Area Wilderness at the end of the day on 13 July (this was only the third time that the BWCAW has been completely closed).

As the smoke drifted eastward across the airport at Thunder Bay, Ontario (METAR identifier CYQT), the surface visibility was reduced to 2.5-3.0 miles at times (below).

A closer view using 1-minute GOES-19 GeoColor RGB images with an overlay of Next Generation Fire System (NGFS) Fire Detection polygons (below) displayed the hot thermal signatures and dense smoke plumes of these wildfires. Over 33000 acres were burned in northeastern Minnesota on this day, with some of the wind-driven fires crossing the border into Ontario.

One example of the rapid rate of wildfire intensification is shown below — just 1.7 hours after initiation, a fire northeast of Ely, Minnesota exhibited the GOES-19 Band 7 detector saturation temperature of 138 C.

Farther to the north over Ontario, one of the wildfires produced 3 pyrocumulonimbus (pyroCb) clouds (below), which exhibited cloud-top infrared brightness temperatures in the -40s C (shades of blue to cyan) and -50s C (shades of red) — and some GLM-detected lightning activity was seen with the 2 larger pyroCbs.

The largest pyroCb (which appeared to be a merger of the initial 2 pyroCbs) eventually exhibited a minimum cloud-top infrared brightness temperature of -58.96 C at 0030 UTC (below).

The cloud-top temperature of -58.96 C was not far below the tropopause, according to a plot of rawinsonde data from Pickle Lake, Ontario (below).

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