SPM 09-28-2017: Multiple Rounds of Rain for the San Juan and Southeast Mountains

Issue Date: Thursday, September 28, 2017
Issue Time: 10:50AM MDT


Another gloomy and rainy day across the Front Range and southern mountains yesterday as the upper level Low over AZ provided lift for multiple rounds of showers. The Low continued to produce southerly winds over Colorado, which sustained the stream of moisture from the Gulf of Mexico. As the jet streak moved over the state with the northward movement of the Low, showers/snow continued overnight along the Front Range and Southeast Mountains. The jet also enhanced the intensity and increased the coverage of storms overnight. This morning, the jet continues to provide lift for the showers east of the Continental Divide over the Southeast Plains. Drier air began working its way into western Colorado during the evening yesterday, so showers over the SW corner of the state ended by 9PM and produced lower 24-hour accumulations.

Several CoCoRaHS stations across the Southeast Mountains recorded amounts greater than 1 inch. The USGS Fort Carson automated gage recorded 1.76 inches. Over Las Animas County, a USGS gage to the northeast of Trinidad, recorded 2.32 inches. A SNOTEL site in the southern Sangre de Cristo range recorded 1.4 inches of rain. Radar rainfall estimates show multiple areas receiving more than 2 inches with 2-hour rain rates up to 0.5 inches. To the west, Pagosa Springs recorded 24-hour totals around 1.15 inches. The highest radar rainfall estimates are over San Juan and eastern Dolores Counties where radar indicates just over 0.5 inches of rain fell. While river gages did record elevated flows due to runoff, there was no riverine flooding reported.

There were no reports of flooding yesterday as of this morning. To see how much rain fell in your area, 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.