Issue Date: Thursday, May 31st, 2018
Issue Time: 9:30 AM MDT

Summary:

A shortwave disturbance embedded in the southwesterly flow aloft brought an increase in moisture and acted as a trigger for scattered showers and thunderstorms across Colorado yesterday. West of the Continental Divide, low-level moisture lacked and limited showers and thunderstorms to a more garden-variety type, producing light rain and gusty winds. The strongest of the wind gusts (56 mph) was reported 5 miles NW of Mack in Mesa County, and a 49 mph wind gust was reported at the Montrose Regional Airport.

East of the Continental Divide, and especially for the lower elevations east of the mountains, low-level moisture was sufficient to provide the fuel for more numerous, stronger thunderstorms. The peak of thunderstorm activity was from the late afternoon through sunset, and storms quickly diminished between sunset and midnight. Periods of moderate-to-heavy rainfall attended the stronger storms; 1 inch/40 minutes was reported 7 miles SW of Calhan in El Paso County.

No flash flooding was reported yesterday. For a look at precipitation estimates in your area, please see our State Precipitation Map below.

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

Summary:

Yesterday was marked by mostly sunny skies and mainly dry conditions thanks to an exiting upper-level trough leaving Colorado under cooler, northwest flow aloft. Enough moisture hung around for another afternoon/evening round of showers and thunderstorms; most were garden-variety, producing light rainfall, a bit of lightning, and gusty winds, but a couple over eastern Colorado became severe, producing large hail over Washington, Yuma, and Kit Carson counties. The biggest hail report of the day was 1.75” diameter, produced by an isolated thunderstorm over Yuma County, 4 miles NNW of Joes. Brief periods of moderate rain attended these thunderstorms, resulting in beneficial wetting rains and not causing any flash flood concerns.

Around midnight, and continuing into this morning, a second round of weak showers/thunderstorms developed across the Southeast Plains, owing in part to a quasi-stationary frontal boundary over northeast New Mexico. This activity produced mainly light rainfall, with no flooding concerns.

Flash flooding was not reported yesterday. For a look at precipitation estimates in your area, please see our State Precipitation Map below.

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Issue Date: Tuesday, May 29, 2018
Issue Time: 10:15AM MDT

Summary:

Active Memorial Day for northeast Colorado and the Urban Corridor. Thunderstorms began to fire over the mountains by early afternoon, but it wasn’t until the late afternoon that they began to move into the Urban Corridor. There was several small hail reports (up to 1 inch in diameter) over the metro area with the line of convection that moved through around 5PM. ALERT rainfall gages recorded 0.79 inches just north of Castle Pines and in Aurora for the 30 minute duration. Most other stations in the metro area recorded between 0.30-0.50 inches of rain.

Another set of storms fired along a frontal/convergence boundary further over the eastern plains. High moisture and favorable dynamics allowed numerous severe thunderstorms to form. There were several tornado and land spout reports over Kit Carson and Washington Counties, as well as in Morgan and Weld Counties. The highlight of the day was twin tornadoes in northern Kit Carson County! There was also a hail report of 1.75 inches in the same area. Overnight, thunderstorms regenerated to the west along a frontal boundary giving Kit Carson County some very heavy rainfall for the second night in a row. A CoCoRaHS station reported 3.15 inches of rainfall north of Bethune and a mesonet station reported 3.72 inches over Flagler. Radar estimates were up to 5.2 inches for the 6-hour period. If correct, this is approximately a 1 in 200 year rainfall event, and this also puts (localized) 48-hour totals at 6.7 inches!

Elsewhere across the state, the Northern Mountains and Northwest Slope got some thunderstorm activity yesterday. A SNOTEL site in Willow Park measured 0.50 inches of rain. Max 1-hour rain rates under the cores yesterday were estimated at 0.50 inches with 24-hour totals up to 1 inch. The showers picked up again early this morning on the backside of the trough.

There were two flash flood warnings issued yesterday. One over the Beaver Creek burn scar and the other over Kit Carson/Yuma County; however, there were no reports of flooding as of Tuesday morning. For rainfall estimates over your area, scroll down to the State Precipitation Map below.

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Issue Date: Monday, May 28, 2018
Issue Time: 10:45AM MDT

Summary:

Strong increases in moisture over the eastern plains and Palmer Ridge, thanks to a frontal passage, helped fuel widespread, severe thunderstorms on Sunday. High instability was able to build by the afternoon due to strong daytime heating. Combined with low-level moisture and increased lift from the low over UT/NV, the perfect environment was created for an afternoon and evening of thunderstorms and severe weather. Storms began to fire along the Front Range and Southeast Mountains, by early afternoon and also along the boundary over the Northeast Plains. As the storms that formed over the higher terrain moved northeast into better moisture (55-60F dew points) and instability, they quickly formed into a convective line. Several Severe Thunderstorm Warnings were issued as well as a couple Tornado Warnings, but no tornadoes were reported. Hail up to 1.75 inches was recorded in Yuma County as well as a gust of 58 mph in Akron. Sterling airport received 1.29 inches of rain with radar estimates as high as 1.5 inches. Max 1-hour rain rates were estimated at 3 inches over Kit Carson County, and a lingering MCS continued through 2AM helping generate 24-hour totals of 3.5 inches.

Despite widespread thunderstorm coverage and overnight rainfall, flooding was not reported on Sunday. For rainfall estimates in your neighborhood, scroll down to the State Precipitation Map below.

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