SPM 09-24-2017: Widespread Heavy Rain and Some Snow for the Higher Elevations

Issue Date: Sunday, September 24, 2017
Issue Time: 10:35AM MDT

Summary:

Widespread showers and thunderstorms formed across the state yesterday as the trough began to slide in from the west. South and southwesterly winds aided in the return of moisture to the state, especially over the eastern plains and southern high country. This allowed for some very impressive rain rates in the early afternoon. Yesterday morning, showers and thunderstorms were already active over the eastern plains and the western portion of the state at the lower elevations. As the system began pulling to the northeast, showers and snow quickly filled in over the mountains. Over the eastern plains, showers and thunderstorms were focused along and behind the slow, eastward propagating cold front. The more convective rain quicwas just east of the Colorado border. By late evening showers over the western portion of the state ceased as drier air worked its way in from the west. Showers over the mountains ended by midnight, and rain continued through this morning over the far eastern plains along the Kansas border.

Over the western portion of the state, CoCoRaHS stations over the higher terrains recorded up to 0.6 inches of precipitation. A SNOTEL station in Grand Mesa National Forest recorded 1.8 inches. Due to the high elevation (above 10,000 feet), most of this precipitation fell as snow. There was a report of 6.3 inches of snow out of Delta County near the SNOTEL gage. Over the Southeast Mountains and southern Front Range, there were two areal flood advisories. The first was for a storm over Colorado Springs that was produced 0.5 inches of rain in 30 minutes. For the 24-hour period, a USGS gage recorded 2.04 inches at Cottonwood Creek and Woodmen Road. The Fountain Creek gage (seen below) reached action level, but it was able to avoid minor flooding. The second areal flood advisory was for the Junkins burn scar where moderate rain was reported falling. Fortunately, there was no flooding reported and creeks are expected to recover today.

Over the eastern plains, quite a bit of rain fell throughout the day and overnight. A USGS gage in Delhi, CO recorded 2.29 inches. Just over the border in Oklahoma, a USGS gage near Kenton, OK recorded 3.6 inches of rain. Radar rainfall estimates are as high as 3 inches with 1-hour rain rates of 2 inches. There was no flooding reported along the Arkansas River, but some of the smaller creeks and arroyos are running in the 90th percentile due to the widespread rainfall. These will be monitored closely as another round of heavy rainfall is likely today over the Southeast Plains and eastern Raton Ridge.

To see how much rain fell in your area, take a peek at 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.