SPM 07-16-2019: Severe Thunderstorms West of the Continental Divide

July 16, 2019 by ·

Issue date: Tuesday, July 16, 2019
Issue time: 10:40AM MDT

Summary:

Severe thunderstorms where reported all along the Front Range and Urban Corridor yesterday as a shortwave passed overhead around 1PM. Moderate to high levels of surface moisture on the eastern plains were pulled westward throughout the morning to aid thunderstorm generation over the Palmer Ridge and high country east of the Continental Divide. West of the Continental Divide things dried out a bit compared to the weekend, as dry air gradually made its way in from the west-southwest. The main story yesterday was severe thunderstorms over the Urban Corridor and Palmer Ridge. Areal Flood Advisories were issued between 4PM and 6PM between Castle Rock and Colorado Springs, with radar derived measurements of 2.5 inches over the area over a 1.5 hour period. Another Areal Flood Advisory was issued over Lincoln County at 6:30PM, with radar deriving 3 inches of rain over a 75 minute period, which is a 1 in 100 year event! No flooding was reported over the areas. Other notable reports to the NWS include:

1.5 inch diameter hail: 5 miles N of Lyons (Larimer County)
1.25 inch diameter hail: 7 miles NE of Greenland (Douglas County)
60 mph wind gust: near Akron (Washington County)

Surface reports from CoCoRaHS measured 1.30 inches near Karval in Lincoln County, 1.12 inches of rain near Jamestown in Boulder County, 1.15 inches of rain near Akron in Washington County, and 1.03 inches of rain near Larkspur in Douglas County.

For a look at precipitation over your area, please visit 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 vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.
Filed Under: State Precipitation Map ·

SPM 07-15-2019: Another Round of Afternoon and Evening Thunderstorms Produce Heavy Rainfall

July 15, 2019 by ·

Issue Date: Monday, July 15th, 2019
Issue Time: 9:40AM MDT

Summary:

The high pressure ridge remained intact on Sunday, which also controlled Saturday’s weather pattern as well. Flow turned more westerly, which allowed afternoon thunderstorm activity to spill into the adjacent plains and far eastern plains of Colorado. With high moisture still in place, some heavy rainfall was recorded with numerous Flash Flood Warnings and Areal Flood Advisories issued across the state.

Over western Colorado, totals were greatest over the San Juan Mountains and eastern Gunnison County. Highest radar estimated rainfall totals over these areas ranged from 0.50 to 1 inch. The Saint Elmo’s SNOTEL site recorded 1.4 inches for the 24-hour period. A Flood Advisory was issued for this storm, but as of this morning, there was no flooding reported. To the east, numerous CoCoRaHS stations just west of Fort Collins recorded rainfall just over 1 inch with the highest total at 1.23 inches for the 24-hour period. Deeper moisture over the Northeast Plains and slow steering winds allowed storms that formed on a SW to NE oriented boundary to drop 2 inches of rain at the cores of the storms. The storm that radar indicated dropped just over 2.5 inches in north, central El Paso County received a Flash Flood Warning around 4PM MDT. Again, flooding had not been reported to NWS as of this morning, but these were some impressive 1 to 2 hour totals associated with the PW surge.

To see estimated precipitation totals over your neighborhood on Sunday, scroll down 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 vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.

Filed Under: State Precipitation Map ·

SPM 07-14-2019: Hot with Scattered Thunderstorms, Street Flooding

July 14, 2019 by ·

Issue Date: Sunday, July 14th, 2019
Issue Time: 9:10 AM MDT

Summary:

High pressure aloft centered over the southern Rockies yesterday allowed high temperatures to climb to seasonally hot temperatures. Underneath the ridge of high pressure, southwest flow continued to transport good mid-level moisture into the state, which set the stage for a classic Colorado mid-summer thunderstorm day. Scattered storms got an earlier start over the mountains, kicking off by late-morning over the higher elevations. Most storms over the High Country produced light-to-moderate rainfall and gusty winds, but a stronger storm near Montrose produced a few severe reports: (1) 62 mph wind gust (2 miles NW of Montrose, (2) a tree blown over onto a car in Montrose, and (3) minor street flooding in Montrose.

East of the mountains it took a few more degrees of heating to spark activity, and isolated storms began around 1 PM. Initially, they produced light-to-moderate rainfall and gusty winds owing to a relative lack of moisture below cloud bases. However, as the day progressed, outflow boundaries from earlier storms moistened the near-surface layer, and allowed for a couple strong thunderstorms over the Denver metro during the evening, producing gusty winds, heavy rain, and hail. 1.0 inch diameter hail was reported 3 miles ENE of Broomfield, and 0.88 inch diameter hail was reported 2 miles SSW of Buckley AFB. The big story, though, was the heavy rainfall. Street flooding occurred across portions of Denver:

Highway 6 under Federal Boulevard
Intersection of W. Colfax Avenue and Raleigh Street
Iowa Avenue between Santa Fe Drive and Broadway

A few light rain showers were ongoing after sunrise this morning over portions of the Southwest Slope, San Juan Mountains, Grand Valley, and Central Mountains regions. 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 vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.

Filed Under: State Precipitation Map ·

SPM 07-13-2019: Thunderstorms over the Northeast Plains and High Country

July 13, 2019 by ·

Issue date: Saturday, July 13, 2019
Issue time: 10:40AM MDT

Summary:

Widespread rainfall returned to the state yesterday as midlevel moisture returned to the area. A cold front dropped in from the north midday causing enhanced convergence along the Palmer Ridge. A line of moderate to severe thunderstorms formed over the Northeast Plains along the boundary and traveled slowly to the northeast. CoCoRaHS stations near Keensburg in southern Weld County reported 0.65 and 0.51 inches. An Areal Flood Advisory was issued over the area but there were no reports of flooding. Radar derived rainfall of up to 1 inch along I-76 from Brighton to the Nebraska border. Hail of 1 inch diameter was reported to the NWS near Julesburg in Sedgwick County. Dry air below the cloud bases produced gusty winds over the south Urban Corridor, with a report to NWS of 60 mph wind gusts near Colorado Springs Airport. Precipitation over the high country remained light, with most CoCoRaHS stations reporting less than 0.15 inches. A flash flood warning was issued over the Hayden Pass burn area at 4pm with radar deriving 0.5 inches of rain over an hour, but there were no reports of flash flooding.

For a closer look at precipitation over your area, please view 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 vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.
Filed Under: State Precipitation Map ·
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