Fast-moving wildfires in Washington State

September 7th, 2020 |

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), Fire Temperature Red-Green-Blue (RGB) + GLM Flash Extent Density (FED) and “Clean” Infrared Window (10.35 µm) images (above) showed the smoke plume and thermal signature of the Pearl Hill Fire — which made a rapid ~50-mile run south-southwestward across northern Washington State on 07 September 2020. During this time, northwesterly winds gusted to 40 knots (46 mph) at Omak (KOMK) near the source of the fire. Downwind of the fire, smoke reduced the visibility to 1.5 miles at times in Wenatchee (KEAT).

Later in the day, smaller fires which started burning farther to the east exhibited similar (albeit much shorter-distance) southwestward runs.

Using NUCAPS soundings in and around fire locations

September 7th, 2020 |

GOES-16 Visible (0.64 µm) hourly imagery, 1811-2311 UTC on 6 September 2020 (click to enlarge)

GOES-16 Visible imagery, above, during the late afternoon on 6 September, shows an invigoration of the Cameron Peak fire in Larimer County, Colorado, with visible evidence of a pyrocumulus development.  Are there tools a forecaster can use to anticipate such extraordinary afternoon fire growth?

NOAA-20 overflew Colorado shortly after (NOAA-20 orbits can be viewed at this website) 2000 UTC on 6 September (see NUCAPS Sounding availability points below;  note that the date of these plots — 1951 UTC — corresponds to the time of  the first NUCAPS swath is available in AWIPS from this NOAA-20 pass;  for this ascending pass, that swath is near 40 S latitude!)

NUCAPS Sounding Points from the 2000 UTC overpass on 6 September 2020 (Click too enlage)

What do the NUCAPS Sounding surrounding Larimer County Colorado look like?  The animation below steps through the profiles surrounding the fire.  Consider using the LCL and EL information (and other information) in these profiles when diagnosing the likelihood of convection developing in response to an intense fire.  On this day, NUCAPS showed steep mid-tropospheric lapse rates that help support pyrocumulonimbus.

Select NUCAPS Soundings and thermodynamic variables (from AWIPS, locations as indicated) on 6 September 2020 (Click to enlarge)