Wildfires remained active across northern Colorado by 20 Oct 2020. The Cameron Peak Fire, west of Fort Collins, had grown to over 200,000 acres, the largest wildfire in Colorado recorded history.

Viewing GOES-East SWIR imagery over northern Colorado during the morning of Oct 20, a hot spot is barely apparent from the Cameron Peak Fire, just west of Fort Collins (Fig 1-2 top). From the SWIR and other channels, one easily finds that this is due to cloud cover. However, the western US has the benefit of overlapping 5-min (CONUS/PACUS) imagery from GOES-East and GOES-West satellites. Upon viewing GOES-West SWIR imagery, a hot spot associated with the Cameron Peak Fire is readily apparent through the morning (Fig 1-2 bottom).

Viewing Natural Color Fire RGB imagery, the quasi-stationary cloud masking the hot spot in GOES-East imagery is obviously situated to the east of the wildfire in GOES-West imagery, allowing for a clear view of the hot spot (Fig 3-4). This is a good visualization of parallax, and how clouds will appear situated at different locations relative to the surface in reality, and between GOES-East and GOES-West.

It is important for forecasters in the west to remember that they have two options for 5-min geostationary imagery, and that there are situations where one may provide additional insight over the other.

Bill Line, NESDIS and CIRA