SPM 09-29-2017: Ongoing Showers with Northward Movement of the Upper Level Low

Issue Date: Friday, September 29, 2017
Issue Time: 10:40AM MDT


The upper level low to the west of Colorado continued to promote rain and cloudiness across the majority of the state again yesterday. The morning began with showers over the high terrain sustained by weak upslope flow and high moisture. Heavier rain was occurring over the eastern plains, which was supported by the upper level jet as the Low tracked north. By mid-afternoon, the showers over the eastern plains had worked their way over the KS border, and the dry slot had moved into western Colorado. The drier air to the west limited widespread showers and heavy rainfall, though some storms still dropped a decent amount of precipitation over the valleys and Northern Mountains. Overnight showers and snow lingered in the mountains with the highest accumulations over the Southeast Mountains/Raton Ridge. The showers over the south were enhanced by a shortwave rotating around the Low, which helped increase 24-hour rainfall totals. By early this morning, the showers had drifted into the Southeast Plains and have sustained themselves with lift from the jet stream and the shortwave. The isolated showers will continue to gradually move to the northeast throughout the morning.

Southwest flow over western Colorado helped limit rainfall totals when compared to Wednesday. A bit more moisture managed to maintain itself over the eastern San Juan Mountains. CoCoRaHS stations near Pagosa Springs recorded totals from 0.15 to 0.3 inches. A bit of instability was able to build over the western valleys and afternoon thunderstorms produced hail and storm totals of 0.5 inches. Along the Front Range, the Eldora SNOTEL station recorded 0.9 inches. Radar rainfall estimates were up to 1 inch in this area. The highest accumulations were again over the Southeast Mountains and Raton Ridge. The heavier rain fell in ungagged areas, but there was a report of 1 inch in Kim, Colorado. Radar rain estimates are up to 1.5 inches with 2-hour totals up to 1 inch.

There were no reports of flooding Thursday. 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.