A cloud-to-ground lightning strike initiated a wildfire in southeast Colorado during the early evening of 18 October 2019. A progressive shortwave trough moving across Colorado sent a cold front south down the eastern Colorado plains during the afternoon and evening. Lift associated with the trough and cold front, and weak instability aloft, aided the development of showers and weak thunderstorms ahead of and along the frontal boundary. Dry low levels and dry fuels in place across the eastern Colorado plains along with gusty north winds behind the front aided the growth and southward spread of the lightning-initiated wildfire during the evening. Given the expected conditions, a Red Flag Warning for dry lightning was issued the morning of the 18th.
GOES-East water vapor imagery shows the shortwave trough quickly moving east across Colorado on 18 Oct (Fig 1). The associated frontal boundary is also diagnosed in water vapor imagery racing south across the central high plains.
The National Lightning Detection Network (NLDN) detected a negative cloud-to-ground lightning strike over SSE of Lamar at 2315 UTC (Fig 2). Interestingly, neither the GOES-West nor GOES-East GLM detected the flash associated with this particular CG. Shortly after the CG detection, under clearing cloud cover, a hot spot was noted in GOES-East 3.9 um shortwave IR imagery at the location of the CG strike. The fire accelerated south thereafter as north winds picked up behind the front. NWS Pueblo provided spot forecast information to local fire crews working the wildfire overnight.
Overnight, the JPSS NOAA-20 VIIRS Day Night Band detected light associated with the wildfire during the late night hours, along with the scorched earth in its wake to the north (Fig 3).
The next morning, GOES-East visible imagery showed the north-to-south oriented path of scorched earth associated with the wildfire emanating south from the location of the previous day’s lightning strike (Fig 4).
Bill Line, NWS