SPM 08-12-2019: Severe Thunderstorms and Giant Hail over the Northeast Plains

Issue Date: Monday, August 12, 2019
Issue Time: 9:35AM MDT

Summary:

All the ingredients were present over the Northeast Plains for severe thunderstorms yesterday and Mother Nature sure cashed in. High levels of instability, moisture and wind shear enabled slow moving thunderstorms to produce large hail, gusty winds, heavy rainfall and a few tornadoes. Storms began over the Front Range around noon and moved over the surrounding plains starting around 2PM yesterday, tracking to the east/northeast. One storm was capable of producing 4.5 inch diameter hail near Otis in Washington County, that’s grapefruit sized hail! Over 15 severe thunderstorm warnings were issued for storms over the eastern plains, along with 10 tornado warnings. In total there were 14 reports of hail, which ranged in size from 1 inch to 4.5 inches in diameter, and 6 reports of tornados. Rainfall was plentiful as well, with a CoCoRaHS station in central Yuma County measuring up to 2.28 inches of rain over the 24-hour period. Radar derived up to 2.5 inches over rain over the area, with rain up to 1.5 inches throughout the Northeast Plains. An Areal Flood Advisory was issued over northern Washington County yesterday but there were no reports of flooding in the area. Here are some of the notable storm reports given to the NWS yesterday:

  • 4 inch diameter hail was accompanied by a tornado near Otis in Washington County
  • 2.75 inch diameter hail and a tornado in western Yuma County with damage reported to a windshield
  • 1 inch diameter hail near Ponderosa Park in Elbert County
  • Thunderstorm wind damage caused downed power lines, roofs to be ripped off of houses and a steel building in a concrete base to be removed from the ground in Cheyenne County near Arapahoe

Back to the west there was moderate to high rainfall over the high country as well. The Flat Top Mountains had 24-hour accumulations on the higher end, with Dead Horse RAWS station measuring 0.8 inches in eastern Rio Blanco County. Radar derived up to 0.5 inches over the Northwest Slope and Northern Mountains. Heavy rainfall was reported all throughout the San Luis Valley and eastern San Juan Mountains. A CoCoRaHS station in Alamosa recorded up to 0.62 inches, which is very high for the area. To the west heavy rainfall reports increased to 1.7 inches in northeast Conejos County. A CoCoRaHS station near Durango measured 0.6 inches just to the south of the 416 burn area. No flooding was reported in Colorado Yesterday.

For a look at precipitation over your area, please visit 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 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.