SPM 09-27-2017: Showers for the Front Range and Southeast Mountains

Issue Date: Wednesday, September 27, 2017
Issue Time: 10:50AM MDT

Summary:

As the disturbance from the end of last week began to move eastward, general subsidence occurred across the state. The settled weather pattern did not last long as the next trough began to dig south over the desert southwest. By late afternoon, showers associated with the Low pressure over Arizona arrived to the southern mountains. At the same time, weak upslope flow initiated showers along the Front Range. Precipitable Water (PW) and instability were limited, so the precipitation yesterday was in the form of general showers and stratiform rain. Rain continued overnight and into this morning along the Southeast Mountains. Overnight low temperatures remained relatively warm due to the increased cloud cover.

Despite relatively low atmospheric moisture, persistent rainfall yielded some impressive 24-hour totals along the Front Range and Southeast Mountains. Over the Front Range, a handful of CoCoRaHS stations in Clear Creek, Jefferson and Park Counties recorded 0.65 inches. Over the Southeast Mountains, CoCoRaHS totals were in the 0.3 to 0.5 inch range. Radar estimated 24-hour rainfall just over 1 inch in Las Animas County. Drier air over the southwest Colorado state made showers more isolated in nature yesterday. SNOTEL stations over the San Juan Mountains recorded up to 0.3 inches. While there was no flooding reported Tuesday, it is important to note the 24-hour totals. Increased moisture is forecasted from Wednesday to Friday, and an uptick in rainfall intensity is expected. Antecedent rainfall can saturate the soil, which will increase runoff and the potential for mud flows and debris slides in the high country.

To see how much rain fell in your neighborhood, scroll down to the State Precipitation Map below.

Click Here For Map Overview

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 accumulation ending time is 6AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas since 2012. The home button in the top left corner resets the map to the original zoom.

Note: We have identified a possible underestimation in QPE over the southwest part of the state. We are working to on this issue, and will provide an update as soon as possible.