SPM 08-10-2018: Westward Shift in Mountain Convection

Issue Date: Friday, August 10th, 2018
Issue Time: 09:40 AM MDT

Summary:

Northerly flow aloft with a slight easterly component kept convection on Thursday confined to the mountains. The SPM also shows the thunderstorms that formed early this morning over the Northeast Plains with a passing vorticity max. With subtropical moisture to the south, widespread flooding was not anticipated or realized. A westward shift in the main axis of convection brought some much needed rainfall to the eastern San Juan Mountains and southern Central Mountains. Storm motion was south yesterday, so after storms formed over Saguache County they brought rain into the San Luis Valley. CoCoRaHS stations in Alamosa recorded between 0.3 and 0.4 inches of rainfall. To the east, the Whiskey Creek SNOTEL site (south of La Veta) recorded the largest 24-hour observation at 0.9 inches. Storms yesterday tracked mostly over remote areas with limited gages. Paired with radar beam blockage, the best estimates for average totals from yesterday’s rainfall are between 0.25 and 0.6 inches. Lastly, an areal flood advisory was issued for the Chalk Cliffs in Chaffee County. There was no flooding reported for Thursday.

To see how much precipitation fell over your area yesterday, scroll down to the State Precipitation Map below.

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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 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.