1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Fire Temperature Red-Green-Blue (RGB) images (above) showed diurnal changes in the Cameron Peak Fire in northern Colorado on 14 October 2020. Aided by strong westerly winds at the surface (with peak gusts in the 50-70 mph range), the fire’s thermal signature initially began to increase in areal coverage and spread rapidly eastward — however, following the passage of a cold front around 18 UTC, an influx of cooler air with higher relative humidity halted this eastward expansion of the fire (with the thermal signature then retreating westward and diminishing in size). By that evening, the fire’s total burned area had grown to 158,300 acres, making it Colorado’s largest wildfire on record. While there was some pyrocumulus development over the fire source region, this large and hot fire did not produce a pyrocumulonimbus cloud.

Another view of the fire using 5-minute imagery from GOES-16 provided quantitative products such as Fire Power, Fire Temperature and Fire Area (below) — these 3 products are components of the GOES Fire Detection and Characterization Algorithm (FDCA). Surface observations showed that during the morning hours smoke was restricting surface visibility to 3 miles at Fort Collins (KFNL) and 5 miles at Greeley (KGXY).

GOES-16 True Color Red-Green-Blue (RGB) images created using Geo2Grid (below) indicated that one portion of the Cameron Peak Fire smoke plume was transported eastward across parts of Nebraska and Iowa, with another part of the plume moving southeastward across Kansas.

A toggle between Terra MODIS True Color and False Color RGB images on 14 October from the MODIS Today site (below) showed the  Cameron Peak Fire smoke plume as well as its large burn scar (shades of red).

In a comparison of MODIS False Color RGB images from Aqua on 13 October and Terra on 14 October (below) the growth of the Cameron Peak Fire along its southeast flank was evident — and several other large fire burn scars were evident across Colorado and southern Wyoming.

Additional aspects of this fire and its environment are discussed here.

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Strong winds on 14 October invigorated the Cameron Peak fire to the west of Fort Collins, producing an extensive smoke plume.  The Day Land Cloud Fire RGB, above, includes the near-infrared 2.25 µm channel (GOES-16 Band 6) that shows the active fire in red and the ‘Veggie’ Band at 0.87 µm (a useful channel to show the burn scar to the west of the active fire). Note that a second fire is detected shortly after 2100 UTC in north-central Grant County to the west-southwest of the Cameron Peak fire.

Vigorous fires occasionally force pyrocumulonimbus clouds (as shown here, for example, for the Cameron Peak fire in early September).  What tools are available in mid-day to assess the likelihood of a pyrocumulonimbus?

NOAA-20 overflew Colorado (from this site) shortly after 2000 UTC on 14 October 2020.  NUCAPS Profiles from that overpass can be used to diagnose atmospheric stability. Gridded NUCAPS fields show lower stability south of the fire, and greater stability north, over Wyoming (the colorbar of the field has been altered to highlight lapse rates between 5 and 8 C / km). A similar plot showing 700-300 mb lapse rate also shows the increase in stability to the north.

The increase in stability as the airmass moves from the north will affect the likelihood of Pyrocumulonimbus development.  This (large) 4-panel animated gif (from this blog post) shows the evolution of the fire — with 1-minute time-steps — during the day on 14 October.

The six NUCAPS soundings that surround the fire show the steep upper-tropospheric lapse rates, below.

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Radar imagery from the upper midwest at 1858 UTC, below, showed convection moving into lower Michigan. NUCAPS thermodynamics, above, suggest that the convection would not dissipate in Michigan. An elevated mixed layer with lapse rates of 7 C/km between 500 and 700 mb is indicated.

NUCAPS Points for the afternoon pass over Michigan are shown below. Lower clouds are apparent over much of lower Michigan, but the NUCAPS Soundings did converge to values. The sounding point over southwest Michigan, here, and for just southwest of Saginaw Bay, here, show the steep mid-level lapse rates. NUCAPS Lapse Rates can also be viewed at this website from SPoRT; Lapse rates of 850-700 and 700-500 are available.

GOES-16 Visible imagery (0.64 µm), below, along with GLM Observations of Flash Extent Density, show how the convection continued across lower Michigan.

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GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) (above) and Mid-level Water Vapor (6.9 µm) images (below) displayed a well defined leeside cold frontal gravity wave (reference) as it began to propagate southward from Colorado/Kansas late in the day on 11 October 2020. A bore structure eventually developed near the leading edge of the cold frontal gravity wave as it continued moving south over New Mexico/Texas/Oklahoma during the subsequent overnight hours.

As the surface cold front moved southward across the drought-impacted plains of eastern Colorado, 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) and CIMSS Natural Color Red-Green-Blue (RGB) images (below) revealed the hazy signature of blowing dust lofted by post-frontal northerly winds with peak gusts in the 60-80 knot range. Blowing dust reduced the surface visibility to 1-2 miles at several reporting stations, falling to near zero at some locations (causing a multi-vehicle accident along Interstate 70 in Kansas).

GOES-16 True Color images created using Geo2Grid (below) provided a clearer view of the blowing dust along and immediately behind the cold front across the Colorado/Kansas border region.

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