SPM 09-09-2018: Mid-Level Moisture Combined with Passing Disturbance for Scattered Showers/Thunderstorms

Issue Date: Sunday, September 9th, 2018
Issue Time: 9:30 AM MDT

Summary:

A plume of mid-level moisture from the west provided the fuel for an afternoon and evening of scattered showers (and couple thunderstorms) over the High Country. The bulk of the activity occurred over the higher terrain of the Northwest Slope, Northern Mountains, and Grand Valley, and Central Mountains, where moisture coincided best with a passing disturbance. Further south, over the Southwest Slope, San Juan Mountains, and San Luis Valley, conditions remained mostly sunny and dry, with only one or two isolated, gusty showers.

East of the Continental Divide, mainly dry conditions won out during the daylight hours as scattered cumulus clouds bubbled, but resulted in mainly virga and gusty winds. A few showers and thunderstorms moved across the Northeast Plains, Palmer Ridge, and far northern Southeast Plains early this morning as the disturbance worked across the area. Gusty winds and periods of light-to-moderate rainfall were the result.

No flash flooding was reported yesterday. For a look at precipitation estimates in your area, please see 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 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.

SPM 09-08-2018: Scattered Showers and Thunderstorms Dotted Colorado

Issue Date: Saturday, September 8th, 2018
Issue Time: 9:30 AM MDT

Summary:

The meandering upper-level trough shifted across Colorado yesterday, resulting in more sunshine and slightly warmer temperatures across the state as compared to Thursday. The Eastern Plains held on to their cloud cover and fog the longest, thanks to weak, low-level, easterly flow during the morning hours. As temperatures warmed into the afternoon, a few isolated showers/thunderstorms dotted the High Country, with a couple isolated showers east of I-25. Light rain and gusty winds were the main impacts. All shower activity came to an end by 9 PM.

No flash flooding was reported yesterday. For a look at precipitation estimates in your area, please see 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 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.

SPM 09-07-2018: Flash Flooding of Butter Creek Due to Slow Moving, Heavy Rain Producing Storms

Issue Date: Friday, September 7th, 2018
Issue Time: 09:30 AM MDT

Summary:

High low-level moisture and slow steering winds combined for another day of heavy rainfall in the mountains. Over western CO, a bit more dry air had worked its way in from the west, so storms were more isolated on Thursday when compared to Wednesday. The most widespread rainfall was over the San Juan Mountains were radar indicates 0.25-0.4 inches of rainfall fell. In northern Delta County, the Park Reservoir SNOTEL recorded 1.1 inches for the 24-hour period.

Over eastern Colorado, the DCVZ set up, which allowed storms to form over the adjacent plains in addition to the mountains. One inch of rain was recorded over northern Adams County with the heaviest rainfall over western Elbert County. A CoCoRaHS station near Simla recorded 1 inch. Over the Southeast Mountains, the largest observation of the day occurred. A CoCoRaHS station recorded 1.29 inches near Cotopaxi. This storm trigged major flash flooding at Butter Creek likely due to increased runoff over the Hayden Pass burn scar. Thankfully, no injuries or damage were reported.

To see how much precipitation fell over your area yesterday, scroll down to the State Precipitation Map below. Just a reminder that Pueblo’s radar is down for routine maintenance from 8AM on September 5th – 5PM on September 9th. This may affect some of the totals in the SPM below and ground observations are the best estimate of rainfall over the Pueblo forecast area. More details here: Pueblo Weather Radar Outage

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 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.

SPM 09-06-2018: Heavy Small Hail and Rainfall Causes Urban Flooding Issues

Issue Date: Thursday, September 6th, 2018
Issue Time: 10:10 AM MDT

Summary:

Post-frontal moisture return put PW values at Denver and Grand Junction in the 90th percentile for this time of year on Wednesday. Overnight rainfall on Tuesday was a strong indication of the potential for heavy rainfall yesterday. During the morning hours, dew point along the Urban Corridor were in the mid-50Fs. The air itself felt quite humid. By early afternoon, storms began to fire along the higher terrains and were aided with upper-level support of a passing vorticity max. With nearly stationary storms in a high moisture environment, quite a bit of rainfall fell yesterday. Just a reminder that Pueblo’s radar is down for routine maintenance from 8AM on September 5th – 5PM on September 9th. This may affect some of the totals in the SPM below as ground observations were the best estimate of rainfall over the Pueblo forecast area. More details here: Pueblo Weather Radar Outage

A strong storm moved into the Urban Corridor during the afternoon hours and dropped quite a bit of hail with the low top thunderstorms. Guessing this inflated some of the rainfall observations, though quite a bit of rainfall did occur. Flooding was reported at Kipling and 25th Avenue in Lakewood around 4:30 PM with some cars stalled out in the same area. An Areal Flood Advisory was issued for this storm. Radar estimated up to 2 inches of rain fell over Jefferson County in the 1 to 2 hour period. Snow was reported above 13,000 feet with totals in Clear Creek up to 1.5 inches. An Areal Flood Advisory was also issued for this area. The Southeast Mountains also had storm totals over 1 inch as indicated by observations, which are not included on the SPM below. Over the San Juan Mountains totals were just over 0.5 inches with totals in the Central Mountains between 0.3 and 0.4 inches.

To see how much precipitation fell over your area yesterday, scroll down to 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 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.