SPM 07-16-2021: Severe Thunderstorms Over Palmer Ridge and Eastern Plains

Issue Date: Friday, July 16, 2021
Issue Time: 9:30 AM MDT

Summary:

Isolated thunderstorms began to fire in the early afternoon on the Northwest Slope, Grand Valley and Northern Mountains, as well as the Palmer Ridge, including an early severe-warned thunderstorm around Limon. As the afternoon progressed, storms generally made their way eastward, filling in to the Front Range Mountains and spilling over to the Urban Corridor.

In the Grand Valley, radar indicated heavy rain warranted a Flash flood warning for the Pine Gulch burn area. However no flooding was ultimately reported. Due to the rural nature of burn scar, there are limited precipitation observations for the area.

Rainfall rates from afternoon storms that spilled on the Urban Corridor were low, which translated to low precipitation totals along the Front Range and Urban Corridor, Trace– 0.2 inch observations were reported from Fort Collins to Denver. Storms were more severe along the Palmer Ridge and produced heavier rainfall, Matt Minnillo shared the following video on twitter of heavy rain and hail causing street flooding in Colorado Springs.

Roads covered in water and hail on Tutt north of Woodmen. #cowx #ColoradoSprings pic.twitter.com/vmAbwnzCEl

— Matt Minnillo (@MattBlueThunder) July 16, 2021

Up to 0.97 inches was reported in Colorado Springs from a CoCoRaHS observer, with 0.2-0.45 inch observations scattered across the city. For rainfall estimates in your area, check out the State Precipitation Map at the bottom of today’s post.

The main risk from the severe storms on the Palmer Ridge and Southeast Plains was high winds and damaging hail. A 2 inch (hen egg) hail stone was observed by a trained spotter in Karval in Lincoln County. A supercell formed and split in rural Las Animas county, also producing heavy rain, large hail and high winds. The Pueblo NWS shared the following 3D radar interpolation of the splitting cells.

Take a look at this splitting supercell down in Las Animas County. Both were likely severe, but thankfully they were over an open field. #COwx #Colorado pic.twitter.com/ZaWqgAXM9d

— NWS Pueblo (@NWSPueblo) July 16, 2021

In the Northern and Central Mountains, fairly high humidity and seasonal temperatures over the Muddy Slide and Morgan Creek fires have helped to moderate fire behavior, even with isolated thunderstorms producing little rain and gusty outflows. There was still plenty of smoke in the air from these fires, and those in the surrounding Western State, causing poor air quality.

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 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.
Note: The 24-hour, 48-hour and 72-hour total precipitation do not contain bias corrections today due to errors in the CoCoRaHS data. This means there may be underestimations in QPE over the southwest and southeast corners of the state.