SPM 06-28-2020: Isolated Heavy Rainfall Limited to Eastern Areas

Issue Date: Sunday, June 28th, 2020
Issue Time: 9:30AM MDT


Shower and thunderstorms activity subsided sharply after Friday’s active day, as a disturbance moved east out of Colorado. However, some residual moisture and favorable dynamics support isolated to widely scattered activity mainly across the Palmer Ridge, Northeast Plains and Southeast Plains. Due to large dewpoint depressions (dry sub-cloud layer), it was once again difficult to estimate the highest rainfall. The highest rainfall amounts came from Yuma, Kit Carson and Cheyenne counties. This morning’s AHPS analysis suggested more than 1.5 inches of rain fell in an isolated stretch between Kirk and Idalia in Yuma county. On the one hand, this seems to be supported by an official report of 14 inches of floodwater in the vicinity of Idalia. On the other hand, of the three rain gages in the area of this rainfall, two from the CSU CoAgMet network and one from the RWIS network (all available through the University of Utah MesoWest data archive), the highest amount recorded at the three was less than 0.5 inches. This is supported by our official MetStormLive product shown below. The current thinking is that there was likely a very isolated region that measured a quick 0.5 to 1.0 inch of rain in less than 15 minutes, which resulted in a localized area of flooding where drainage was poor. Further substantiating this idea is the fact that there was almost no response in the nearby streamflow gauges on the North Fork and South Fork of the Republican River and a few nearby irrigation ditches (see the updated Colorado Department of Water Resources for a useful summary of near real-time streamflow data).

Elsewhere, isolated showers and thunderstorms produced generally less than 0.25 inches of rainfall leading to a warm and pleasant summer day.

For precipitation estimates in your neighborhood over the last 24 to 72-hours, scroll down to the State Precipitation Map below.

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The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The 24-hour, 48-hour and 72-hour total precipitation contain bias corrections that are not disaggregated into the hourly estimates, so there will likely be some differences. The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.