With a monsoon pattern well in place, an abundance of moisture was available over southern Colorado by 12 July 2017. With very weak steering flow and marginal instability present, widespread slow-moving convection was expected across the southern Colorado mountains and plains. Of most concern was the flash flood potential in the vicinity of burn scars on terrain. A slow-moving thunderstorm or train of storms over a burn scar would lead to rapid flooding in areas downhill of the scar/drainage.  Since burn scar flooding situations can arise quickly, having the most up-to-date observational data is vital to providing a timely forecast/alert. Given the threat, 1-min imagery from GOES-16 was requested by WFO-Pueblo and granted.

1-min satellite imagery from GOES-16 enhances forecaster situational awareness to areas of new convective development (or movement of storms) over burn scars. Forecasters can diagnose, with more lead-time than ever and in essentially real-time, the development of convection posing a threat to a burn scar. This, in turn, will alert the forecaster to monitor radar closely over that area and notify points of contact of the impending threat.

Similarly, early signs of storm weakening could be identified in the 1-min data, signifying to a forecaster the area would be safe for the time being. This was mostly the case on the 12th. Though widespread convection with heavy rainfall occurred, they mostly avoided the burn scars. The example below shows convection developing quickly southwest of the Junkins burn scar a couple of times, but weakening as they approached the scar (Figure 1).

Figure 1: GOES-16 1-min visible/IR image combination. Black contours represent burn scar outlines. Junkins burn scar is in center of image. Note convective bursts southwest of the burn scar weakening prior to reaching the burn scar. Full resolution: https://satelliteliaisonblog.files.wordpress.com/2017/07/20170712_1min_sw_junkins.gif

The heaviest rainfall ended up falling in far eastern Colorado in Kiowa county. Reports of over 2″ of rain were received, and radar estimated over 5″ in one area. The heaviest rainfall occurred where GOES-16 indicated the presence of highest Precipitable Water amounts (over 1.2″), shown in Figure 2.

Figure 2: GOES-16 Precipitable Water.

– Bill Line, NWS

“The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. Users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized.”