SPM 08-30-2017: Isolated Storms With Short-term Heavy Rainfall; Western Heat Continues

Issue Date: Wednesday, August 30, 2017
Issue Time: 11AM MDT

Summary:

With just enough moisture remaining in the boundary layer, combined with plenty of morning sunshine to heat things up, isolated to widely scattered thunderstorms roamed Colorado’s landscape once again on Tuesday. With mid-level subsidence as a backdrop, storms had a hard time growing in size and lasting much longer than 1 hour. However, lucky locations in the High Country and nearby foothills received a quick 0.25 – 0.5 inches in less than 1 hour. The highest storm coverage was likely over the Palmer Ridge (specifically El Paso County), Weld County as well as the San Juans. The highest CoCoRaHS observation was 0.41 inches in Montezuma County. However, radar-based estimates suggest up to 1 inch may have fallen in remote parts of Weld County. A brief, precautionary Areal Flood Advisory was issued for the Hayden Pass burn scar, however, flooding was not reported as of this morning. The eastern parts of the scar likely received up to 0.25 inches of rain, which could be enough to cause runoff over the sensitive ground depending on how fast the precipitation fell.

Across the Western Slope, heat continued in full force. Grand Junction tied a record high temperature for the date with a reading of 98F as boundary layer moisture mixed out and allowed the sun to efficiently heat the surface. Relative humidity values briefly dropped below 15% across the High Country and lower elevations west of the Continental Divide.

Flooding was not reported on Tuesday. For rainfall estimates in your area, check out our 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.