A cluster of thunderstorms made a long trek south through the southeast Colorado plains Thursday night into early Friday morning. The storms produced heavy rainfall and gusty winds, including a 45 knot measured gust at La Junta. Additionally, the storm produced frequent lightning as evidenced by GOES-16 GLM and NLDN CG data. To the west of the storm, low clouds developed along the I-25 corridor in the anomalously moist atmosphere. Low ceilings brought IFR conditions to KCOS and MVFR to KPUB.

Cloud top brightness temperature trends from ABI IR and GLM total lightning trends were analyzed through the night in order to monitor the health of the storm cluster. Given the 45 knot wind report and constant cold IR temperatures and total lightning, SPS’s were issued for the duration of the storm. The 4-panel animation shows several long flashes extending into the anvil stratiform region of the system, from which several CGs were measured by NLDN.

Figure 1: 27 July 2018 GOES-16 FED (TL), AFA (TR), TOE (BR), and KPUX base reflectivity and NLDN CGs (BL). Full res

As the storm advanced south, low clouds spread west to the I-25 corridor. The Nighttime Microphyics RGB was utilized to track the progression of the low clouds and amend/update TAFs. The image combination below shows the nighttime microphysics RGB with IR brightness temperatures overlaid (gray-scale) for the coldest temperatures. GLM Flash Extent Density is also overlaid.  In the RGB, recall that during the warm season, the ~aqua colors represent warm liquid water clouds, the ~tan colors are cooler water clouds, and the red colors are cold ice clouds (overlaid with IR in the animation below).

Figure 2: 27 July 2018 GOES-16 5-min Nighttime Microphysics RGB (color underlay) with IR brightness temperatures overlaid (grayscale) and GLM Flash Extent Density overlaid. Full res

Bill Line, NWS