A potent mid-level trough advanced east through the four corners and Rocky Mountain region during the day 17 April 2018. Strong southwest winds mixing down to the surface along with very low RH and dry fuels led to extreme fire danger across a large portion of the southern US Plains, including southeast Colorado (Fig 1). Wind gusts in excess of 60 mph were measured across the region within a High Wind Warning, including 68 mph at KCOS and 67 mph at KPUB. GOES-16 provided forecasters in the region with detailed views of developing wildfires and blowing dust. 1-min imagery was available in support of this event.
Figure 1: SPC Day 1 Fire Weather Outlook valid 17 April 2018.
Blowing dust originating from the Great Sand Dunes in the eastern San Luis Valley in southern Colorado was clearly apparent in 0.64 km 500 m visible imagery after 1400 UTC (Fig 2). The dust can be seen quickly spreading to the northeast over parts of Pueblo and Colorado Springs and eventually all the way to northeast Colorado within the strong southwest flow. The blowing dust prompted the issuance of a rare Dust Storm Warning by NWS Pueblo. Additionally, smoke plumes from developing wildfires are apparent, including a large fire in the southeast corner of the state.
Figure 2: 17 April 2018 GOES-16 5-min 0.64 um visible imagery. Full res
The 10.3 – 12.3 um “Split Window” difference depicts blowing dust particularly well given the increased sensitivity of the 10.3 um channel to absorption by airborne silicates. In the Figure 3, blowing dust (negative values in this difference product) is visualized by very dark gray to tan colors. This difference is utilized in RGBs to aid in dust identification.
Figure 3: 17 April 2018 GOES-16 5-min 10.3 – 12.3 um split window difference. Full res
NWS forecasters monitored for wildfire hot spots utilizing the rapid updating 3.9 um channel imagery. The 3.9 um channel is the most effective GOES-16 band for detecting wildfire hots pots. Multiple grass fires erupted across southeast Colorado during the day, prompting evacuations in some instances. Figure 4 depicts the evolution of the wildfires during the afternoon and early evening, with dark gray to yellow pixels indicating progressively hotter hot spots.
Figure 4: 17 April 2018 GOES-16 5-min 3.9 um shortwave IR imagery. Full res
Bill Line, NWS
Satellite Liaison Blog 
