Issue Date: Sunday, September 18th, 2016
Issue Time: 9:00 AM MDT

Summary:

Much of the state remained too dry and unfavorable for the production of showers/thunderstorms, leading to a fairly pleasant day for those locations. The exception to this rule was east of a surface trough, which was oriented northeast-to-southwest from Sterling to Alamosa. Better low-level moisture existed for those locations, resulting in good instability and fuel for isolated thunderstorms. Deep moisture lacked, however, keeping rain rates minimal. A shortwave disturbance aloft helped to kick off this activity, which produced a few reports of strong/severe weather:

Tornado (landspouts): 2 miles N of Cheyenne Wells (Cheyenne County), 1 mile W of Cheyenne Wells (Cheyenne County), 4 miles E of Cheyenne Wells (Cheyenne County)
0.88 inch hail: 1 mile W of Yuma (Yuma County)
0.50 inch hail: Yuma (Yuma County)

For a closer look at rainfall totals in your area, please see the STP map below for a look at 24-hour precipitation totals.

Issue Date: Saturday, September 17th, 2016
Issue Time: 9:00 AM MDT

Summary:

Moisture continued its slight downward trend yesterday, bringing precipitable water values to their lowest points in nearly a week. Due to the lack of moisture and support aloft, most areas remained dry yesterday. However, meager instability over the higher terrain of the Palmer Ridge, Raton Ridge, Front Range, and adjacent lower elevations led to the development of a few isolated showers/thunderstorms. Most activity didn’t produce much more than light rain at the surface. One thunderstorm decided to “buck the trend” and produced brief bouts with heavy rain and small hail across the Denver metro area, causing a delay of the Rockies/Padres game. No flash flooding was reported.

For a closer look at rainfall totals in your area, please see the STP map below for a look at 24-hour precipitation totals.

Issue Date: Friday, September 16th, 2016
Issue Time: 9:00AM MDT

Summary

Rain coverage and intensity continued to decrease on Thursday, compared to Wednesday. This was caused by a sharp drop in moisture levels as measured by surface dew point temperatures and precipitable water values. Nonetheless, several clusters of scattered storms formed over the Northeast Plains where just enough instability remained. Despite the marginal moisture, a few storms were able to maintain very strong updrafts and their tracks spanned several counties. In particular, one cell that formed in southern Washington County tracked for hundreds of miles into Kansas, eventually causing flash flooding and strong winds in addition to big hail. So how big was the hail? A report of 2.75 inches was received in Kit Carson County with numerous other reports in the 0.75 to 1.75 inch range. Needless to say, yesterday’s storms certainly made the most of their marginal environment to produce worst-case scenario type hail.

Aside from the hail aspect, some short-term heavy rainfall was also seen on Thursday though high cloud bases were a mitigating factor. The highest 24-hour rain totals from CoCoRaHS was 0.61 inches in Washington County. Radar estimates suggest that up to 1.25 inches of rain fell in eastern Kit Carson County. However, radar estimates should be accepted with caution due to possible overestimation from hail core scattering.

Elsewhere, it was a pleasant, seasonably mild Thursday across the state. Aside from some isolated showers, gusty winds were also common during the mid-afternoon hours.

Flooding was not reported on Thursday. For rainfall estimates specific to your area, check out our Storm Total Precipitation map below.

Issue Date: Thursday, September 15th, 2016
Issue Time: 8:58AM MDT

Summary

Scattered showers and thunderstorms were once again in bountiful supply on Wednesday across Colorado. The approaching trough providing cool temperatures aloft, while sunshine boosted instability, providing two of the necessary ingredients for convective rainfall. For most, rainfall was of the light to moderate variety with up to 0.5 inches falling across many Colorado locations, save the far eastern border where low clouds stuck around. For some, more active weather was observed in the form of gusty winds, hail and heavier rainfall. The highest rain rates were seen over two areas. First, a storm in Weld County rapidly intensified and produced up to 1.5 inches of rain in about an hour or less. Second, a cluster of storms over the Raton Ridge produced up to 2 inches of rainfall, though this fell between gages over rural areas.

In addition to the rainfall, strong wind shear meant that the most robust cells were capable of producing gusty winds and hail. About half a dozen severe thunderstorm warnings were hoisted during the afternoon and evening hours. The most severe storm was likely that over Crowley County, where hail as big as 1.75 inches was noted from multiple reports. Here are some additional notable hail reports:

• 1.25 inches in Moffat and Weld counties
• 0.88 inches in Mesa County
• 0.25 to 0.5 inch hail across many parts of the western slope

Finally, gusty winds up to 55 mph were observed mainly over the western slope both with and without the presence of thunderstorm activity.

Flooding was not reported on Wednesday. For rainfall estimates specific to your area, check out our Storm Total Precipitation map below. Note that rainfall estimates are likely overestimated under hail cores.