Issue Date: Thursday, July 23rd, 2020
Issue Time: 10:50AM MDT

Summary:

A couple storms caused some heavy downpours and minor flash flooding over the western part of the state yesterday as moisture moved its way north through the state. A strong thunderstorm impacted the Glenwood Springs area yesterday, which caused muddy runoff to flood local streets and prompted a Flood Advisory by NWS Grand Junction. Two CoCoRaHS rain gauges reported 0.80 inches of rain near town, and one gauge just south of town reported up to 1.16 inches! The QPE map shows this area of heavy rain just south of Glenwood Springs well, with up to 1 inch estimated. A second area of heavy rain along a south-to-north band over San Miguel and Montrose County in southwestern Colorado prompted a Flood Advisory from NWS Grand Junction due to law enforcement reports of debris on route 145 due to “minor runoff.” The QPE map indicates just over 0.5 inches of rain fell over an isolated part of this area just south of the town of Norwood. An ASOS station just northeast of Norwood picked up 0.26 inches of 24-hour rainfall, and a CoCoRaHS report of 0.35 inches came in from the next town southeast (Placerville). A Weather Underground station just north of the town of Norwood picked up 0.76 inch of rain over two hours from 1-3PM MDT as two periods of heavy rain moved over the area. This indicates the QPE may be underestimating rainfall along the northern portion of this heavy rain band. Other locations across western Colorado also picked up some beneficial rainfall, including reports of 0.43 inch of rain near Pagosa Springs in the San Juan Mountains and 0.38 inch of rain in eastern Moffat County along the Northwest Slope. A few strong wind gusts, up to 53 mph, were also reported over the Grand Valley from thunderstorm outflow.

Some storms also formed over the Denver area, producing gusty outflow winds and up to half an inch of rain over the metro area. A CoCoRaHS report of 0.55 inch of rain was submitted just south of downtown Denver, near Washington Park. An ALERT gage just northeast of the area reported 0.43 inch of rain over an hour. This isolated area was picked up on the QPE map, which indicated up to 0.5 inch of rain fell, agreeing with observations. Lighter rainfall was observed along the northern Urban Corridor as storms moved north during the afternoon, generally staying below 0.25 inch. The QPE is indicating an isolated area of heavy rain up to 1.5 inches over eastern Adams County, but the closest rain gauge from a Weather Underground station only reported 0.27 inch of rain. This enhanced QPE is likely over-estimated. No flooding was reported over the Urban Corridor yesterday.

Thanks to the rainfall over the southeastern portion of the state last week, drought conditions have improved slightly (see image below). Unfortunately, drought conditions also degraded over the northern tier of the state. Hopefully this week’s rain over the northeast corner of the state will improve drought conditions for next week’s drought monitor update.

For 24-hour to 72-hour rainfall estimates in your area, check out our State Precipitation Map below.

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Issue Date: Wednesday, July 22nd, 2020
Issue Time: 11:00AM MDT

Summary:

Some storms fired around noon over the Southeast Mountains and remained anchored over the higher terrain for a couple hours. This caused a Flash Flood Warning to be issued by NWS Pueblo over the Spring Creek burn area at 1:50PM MDT. The highest rain gauge accumulation of 0.36” was sent in by a CoCoRaHS observer near the area. The QPE map shows a very small area of rain totals over the 0.25” threshold, which generally agrees with gauge data. No flooding was reported near the Spring Creek burn scar, so these rain totals likely were not enough to cause issues.

As these storms moved off the higher terrain of the Southeast Mountains, one storm was able to generate 1.01” of rainfall (CoCoRaHS report) over Colorado City in southwestern Pueblo County. This prompted another Flash Flood Warning from NWS Pueblo at 5:47PM MDT. However, no flooding has been reported in the area as of this morning. The QPE map shows this isolated heavy rainfall over southern Pueblo County with up to 1 inch indicated, generally agreeing with the limited gauge observations nearby. The QPE map also shows that additional heavy rain fell to the northeast into Crowley and southern Lincoln counties. This was associated with a linear band of thunderstorms that intensified over this area. Unfortunately, rain gauge observations are not available to verify the up to 2 inches of rain indicated by QPE. The closest gauge over southern Lincoln County (CoCoRaHS) picked up 0.20” of rain.

A group of storms also fired over the southern Front Range between Denver and Colorado Springs. An ALERT gage over far southwestern Douglas County reported 0.94” of rain over an hour, with several other gages nearby picking up over 0.5 inch. This storm tracked southeast over Colorado Springs, dropping up to 0.51” of rain (CoCoRaHS) just west of town. The QPE map over this area appears to slightly underestimate rainfall, especially over southern Douglas County. No flooding was reported over this area, but hail up to 1” in diameter was observed.

The heaviest rain fell over the northeastern corner of the state, where several rain gauges reported over 1 inch of rain. The largest gauge total of 1.40” (CoCoRaHS) occurred over Logan County, with several reports of 1.35” just east in Phillips County. The QPE map shows a large swath from northeastern Weld County through Logan and Phillips counties with rain totals over 0.5 inches and up to 2 inches. The highest QPE totals up to 2 inches over northeast Weld County cannot be verified due to its remote location with no rain gauge observations. This significant rain fell over the evening (starting after 5PM MDT) and overnight (ending around 2AM MDT) as multiple clusters of thunderstorms drifted southeast off the Cheyenne Ridge. This beneficial rainfall brings the 3-day rain totals to 1-2.5 inches for much of this area of northeast Colorado, which will help keep the drought conditions from worsening.

For rainfall estimates in your area over the last 72 hours, check out our State Precipitation Map below.

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Issue Date: Tuesday, July 21st, 2020
Issue Time: 10:40AM MDT

Summary:

Severe thunderstorms developed over the eastern plains yesterday, which created strong winds, hail up to 1.5 inch in diameter, and even flash flooding. Two storms prompted Flood Warnings from the National Weather Service. One storm developed over southeast El Paso County around 3PM MDT, which quickly dropped up to 2 inches of rain and prompted NWS Pueblo to issue a Flash Flood Warning at 3:24PM MDT. Unfortunately, this area is quite remote and no rain gauges are available in the area. QPE estimates over this area are largely from radar estimates. No flooding was reported over this remote location as of this morning. The second storm developed over far northeast Larimer County into northwestern Weld County, between Fort Collins and Cheyenne, WY. Storms re-generated and trained over this area between 2PM and 6PM MDT according to radar. This caused NWS Boulder to issue a Flash Flood Warning at 04:18 PM MDT. A flash flood report was sent in near the town of Carr at 4:47PM MDT, near I-25. A surprising 2.63 inches of 24-hour rainfall was reported near Carr by a CoCoRaHS observer. QPE only shows up to 2 inches of rain over this area, suggesting under-estimation of rain totals. Some other Weather Underground and CoCoRaHS stations reported up to 0.71 inches of rainfall near the area, indicating just how isolated these heavy rain totals were. Outside these two isolated storms, a large area of the Northeast and Southeast Plains picked up between 0.25 and 0.75 inches of beneficial rainfall according to QPE and rain gauge reports.

West of the Continental Divide, storms were weak and stayed over the southern half of the state. The Northern Mountains and Northwest Slope saw mainly sunny skies yesterday. The heaviest rain fell over the Southwest Slope and southern San Juan Mountains, but remained below 0.25 inches. The highest rain report came from Montezuma along the Southwest Slope of 0.24 inches by a CoCoRaHS observer.

For rainfall estimates in your area, check out our State Precipitation Map below.

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Issue Date: Monday, July 20th, 2020
Issue Time: 10:40AM MDT

Summary:

A group of severe thunderstorms swept through northeast Colorado yesterday, bringing heavy rain, strong winds, hail, and even a weak tornado in Phillips County. An impressive 1.83 inches of rain was reported by a CoCoRaHS observer just north of Sterling in northeastern Colorado, and a nearby CoAgMET gage also picked up 1.68 inches of rain, so QPE in this area appears to be underestimated. This heavy rainfall was associated with a large severe thunderstorm that dropped 1-inch hail and produced a 71 mph wind gust over the area. Some crop and power pole damage was reported from this gust near the town of Iliff.

The Palmer Ridge also picked up some decent rainfall as storms fired over the southern Front Range and tracked east. Several CoCoRaHS rain reports and ALERT gages exceeded 0.40 inches (up to 0.44”) over the southern Urban Corridor and Palmer Ridge. The QPE map indicates that storms may have dropped a little over an inch of rain over portions of Lincoln, Cheyenne, and Kiowa counties. One of these storms prompted a Flood Advisory from NWS Boulder over Lincoln County from 4-7 PM MDT.

Storms back over the high country produced more wind than rainfall. A 58 mph gust was picked up at a Basalt mesonet site, and QPE was estimated around 0.25 inches for storms near the area. A storm tracked over the Decker burn scar, which prompted a Flash Flood Warning as radar indicated over 0.3” of rain had fallen. NWS ASOS stations near the area only picked up to 0.07” of rain, so this storm was very isolated over the higher terrain. Additionally, radar-derived QPE likely under-estimated sub-cloud evaporation. As of this morning, no flooding was reported.

For 24-hour to 72-hour rainfall estimates in your area, check out our State Precipitation Map below.

Click Here For Map Overview