Issue Date: Friday, September 2nd, 2016
Issue Time: 9:00AM MDT

Summary

Thursday represented a transitional day for weather across Colorado. A veteran decaying disturbance gave way to a ridge that dominated the eastern Plains, limiting rainfall activity. Meanwhile, a large-scale trough approached from the west, along with a strong subtropical jet anchoring its southern periphery. The result was scattered to widespread shower and thunderstorm activity mainly west of the Continental Divide. However, instability was limited so rain rates were generally of light to moderate intensity. Highest short-term rainfall likely occurred in the southern parts of the state along with the higher foothills of the Palmer Ridge. Up to 1.25 inches of rainfall fell in rural parts of these area, likely in an hour or two. Farther west, 24-hour rain totals of 0.25 to 0.5 inches were common, with isolated high amounts interspersed.

No official flooding reports were received yesterday. For rainfall estimates specific to your area, check out our Storm Total Precipitation map below.

Issue Date: Thursday, September 1, 2016
Issue Time: 9:10AM MDT

Summary

A notable downtick in rainfall coverage was observed on Wednesday as the long-lived upper-level disturbance that affected Colorado’s weather continued to dissipate. Nonetheless, plenty of residual moisture was found east of the Continental Divide with precipitable water values as high as 1.2 inches along the Kansas border. Highest storm coverage was found across the eastern Palmer Ridge and Southeast Plains. Activity started shortly after noon and slow moving storms dumped torrential rainfall over 30 – 90 minute periods. An areal flood advisory was issued across Kit Carson County in the mid-afternoon for field and road flooding. The highest observation in the area was 1.75 inches in Cheyenne County although radar estimates suggest over 2 inches in the area. This complex of storms slowly moved south during the afternoon though it appears rainfall rates were generally below 1.5 inches per hour. A second group of storms formed farther west over the Southeast Mountains, Central Mountains and San Juans. These storms produced less rainfall, perhaps up to 1 inch, but over the higher terrain this can be impactful. An areal flood advisory was issued over Chaffee County, while a flash flood warning was issued over the Hayden Pass fire scar where about 0.4 – 0.5 inches of rainfall fell.

Elsewhere, it was a seasonably warm and relatively calm day with plenty of sunshine. Certainly a nice break after a string of active weather days.

No official flooding reports were received yesterday. For rainfall estimates specific to your area, check out our Storm Total Precipitation map below.

Issue Date: Wednesday, August 31st, 2016
Issue Time: 9:25AM MDT

Summary

Scattered showers and thunderstorms dotted the landscape across large swaths of northeast Colorado. Activity started early, around noon, along the eastern fringes of the Palmer Ridge as well as farther north. These thunderstorms had narrow updrafts and produced only short-term heavy rainfall to the tune of 0.5 inches in 30 minutes. As the afternoon wore on, the smaller updrafts combined to form more threatening storms over the Northeast Plains. Hourly rainfall rates up to 1.5 inches were observed in mostly rural parts of Weld, Washington, Kit Carson and Cheyenne counties. An areal flood advisory was issued for western parts of Cheyenne County for field and roadway flooding.

Later in the afternoon and into the evening, a secondary surge of activity began around 6PM as a push of very moist air, to the tune of dewpoints near 60F and precipitable water around 1.1 inches, moved westward. Intense thunderstorms formed over the northeast part of the Denver metro area, then sent outflow boundaries southward and westward sparking more activity over the next 3-4 hours. With rainfall falling over the most densely gaged area in the state, some very high rainfall rates were recorded. These include: numerous gages exceeding 0.5 inches in 10 minutes, 1.8 inches in 30 minutes near Cherry Creek Reservoir, and close to 3 inches per hour just west of Boulder. Needless to say, roadway and street flooding was common across the entire metro area. Fortunately, the limited area of the heavy rainfall prevented significant riverine flooding, although some impressive spikes were seen in area stream hydrographs. For example, below is the spike on Clear Creek near the South Platte River confluence: 5 to 1000 c.f.s. in a matter of 30 minutes (provisional data).

For rainfall estimates specific to your area, check out our Storm Total Precipitation map below.

Issue Date: Tuesday, August 30th, 2016
Issue Time: 9:05AM MDT

Summary

A slow moving disturbance was in a position to provide favorable dynamics, moisture and upslope flow that resulted in scattered to widespread showers and thunderstorms mainly east of the Continental Divide. Activity started by late morning with northwestward-moving showers over parts of the Southeast Mountains and Raton Ridge. Shortly after noon, stronger thunderstorms began to form over the Palmer Ridge, especially El Paso County, which was hit hard with heavy rainfall, deep accumulations of hail and flooding. Highest 24-hour totals were around 2.3 inches, with most of that falling over a 1-2 hour period. In fact, many stations received over 1.5 inches of rain, which contributed to very high runoff rates. This was compounded by the antecedent rainfall from the previous day that also targeted the area, causing saturated soils and likely maximized runoff. For example, the time series below is from a USGS precipitation gage that measured 3.5 inches over a 36-hour period. Warnings products issued yesterday afternoon included areal flood advisories, flash flood warnings, flood warnings for Fountain Creek and a severe thunderstorm warning for hail. Street flooding was exacerbated by hail accumulation, leading to a few unlucky folks having to be rescued from cars.

The Palmer Ridge was not the only hot-spot yesterday, as other storms were found farther north and east. Isolated rainfall amounts up to 1.5 inches were found with the strongest storms, prompting a short-term areal flood advisory. Elsewhere, the San Juans continued a string of wet days with up to about 0.75 inches of rainfall falling over favored locations. Above about 12,500 feet, graupel showers were seen that coated the higher peaks with a layer of the white stuff.

For rainfall estimates specific to your area, check out our Storm Total Precipitation map below.