SPM 07-11-2018: Uptick in Thunderstorm Coverage over the High Country

Issue Date: Wednesday, July 11th, 2018
Issue Time: 9:30 AM MDT

Summary:

In what was generally a persistence forecast from Monday, Tuesday did see subtle changes that led to an uptick in showers/thunderstorms across the High Country. In particular, a slight increase in precipitable water provided the fuel needed for a few more thunderstorms and their ability to bring wetting rains to the surface. Showers/thunderstorms initiated over mountain ridges around lunchtime as orographic lift teamed up with daytime heat to drive development, drifting over adjacent lower elevations with time, while regenerating new activity over the same ridges. Unfortunately, most of the uptick in moisture occurred in the mid-levels, and the low-levels remained much too dry for good rainfall to reach the surface. This had the positive effect of reducing the threat of flash flooding, especially over area burn scars, but had the negative effect of not making a dent in the drought. The peak in shower/thunderstorm coverage occurred during the late afternoon/early evening, with activity diminishing after sunset and only a few lingering showers over the San Juan Mountains, Southwest Slope, and Northwest Slope into the early morning hours. There’s not much to say about the weather east of the mountains – it was hot and dry, continuing the theme of July so far.

No flash flooding was observed yesterday. For a look at precipitation estimates in your area, please see 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 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 6AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas (post 2012), which are updated throughout the season to include new burn areas. The home button in the top left corner resets the map to the original zoom.