SPM 06-22-2019: Active Weather Welcomed the First Day of Summer

Issue Date: Saturday, June 22nd, 2019
Issue Time: 9:10 AM MDT

Summary:

Mother Nature brought some fireworks to celebrate the first day of Summer, with showers and thunderstorms rumbling over much of the state. Activity got started before Noon over the High Country, mainly north of I-70, then increasing in intensity and coverage through the afternoon and evening hours across Colorado, minus the San Juan Mountain, Southwest Slope, and San Luis Valley regions. It wasn’t until after 5 PM that a few showers began over the Southwest Slope and San Juan Mountains regions, though dry air prevented anything more than a few scattered sprinkles in those areas.

The main culprits behind yesterday’s widespread active weather were an upper-level disturbance and jet streak, combined with a surface cool front. To the east of the mountains and north of Highway 50, abundant moisture fueled the strongest storms of the day, with scattered strong-to-severe storms rumbling across the area. The following severe reports were submitted to the National Weather Service, including a thunderstorm wind damage report of parts of a house in Arapahoe being stripped to the concrete:

95 mph Thunderstorm Wind Gust: 8 miles S of Cheyenne Wells, 9 miles S of Cheyenne Wells
70 mph Thunderstorm Wind Gust: 4 miles S of Cheraw
63 mph Thunderstorm Wind Gust: 1 mile SW of Firstview
62 mph Thunderstorm Wind Gust: Cheyenne Wells, 4 miles SW of Arapahoe
61 mph Thunderstorm Wind Gust: 6 miles W of Elbert
60 mph Thunderstorm Wind Gust: 1 mile N of Fowler, 8 miles SE of Boone, Hugo, Cheyenne Wells
2.75 inch hail: 3 miles N of Matheson
2.00 inch hail: 1 mile N of Simla, 10 miles S of Limon
1.80 inch hail: 3 miles SE of Simla
1.75 inch hail: 5 miles ENE of Matheson, 1 mile W of Simla, 8 miles ENE of Fondis
1.30 inch hail: 9 miles NNW of Simla (additional report of 1.20 inch hail)
1.25 inch hail: 1 mile N of Kit Carson,
1.00 inch hail: 8 miles SE of Boone, 1 mile E of Ordway, 7 miles E of Kiowa, 5 miles SW of Arapahoe, 7 miles WSW of Firstview, 2 miles S of Cheyenne Wells, Cheyenne Wells

Rainfall and high elevation snow are ongoing across portions of the Front Range, Urban Corridor, Northeast Plains, Central Mountains, and Northern Mountains this morning, setting the stage for what will be a cool and wet day. 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 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.

SPM 06-21-2019: Southwest Flow Increases Moisture with Afternoon Storms over Northern Colorado

Issue Date: Friday, June 21st, 2019
Issue Time: 10:45AM MDT

Summary:

The system over the Pacific Northwest begin to drop south today to our west yesterday, which turned flow aloft from westerly to more southwesterly. A dry air mass was advected over the southern half of Colorado with the wind shift, which kept storms high-based over the Southeast Plains. A cold front over northwest Colorado helped kick off thunderstorm activity in the late afternoon, which lasted overnight. 24-hour totals over the Northwest Slope and Northern Mountains were up to 0.8 inches with isolated totals up to 1 inch over the Northern Mountains. Overall, a large swath of the area received 0.5 inches of beneficial rainfall with the highest CoCoRaHS report in the area at 1.08 inches (Craig). This storm likely pushed these regions to or above climatological rainfall for June. Storms yesterday also produced some strong gusty winds with the jet over the area. Gusts from 50 to 60 mph were reported with the thunderstorms. Rainfall and snowmelt allowed the Elk River (near Milner) gage to reach the Minor flooding stage this morning. Areal Flood Advisories have been issued for the Northwest Slope and Northern Mountains through Saturday as flows in the area will remain elevated from rain and snowmelt.

To the east, a shortwave combined with diurnal flow, a surface trough and moisture to kick off storms and a couple Severe Thunderstorms over the Front Range and Palmer Ridge by 3PM. 1 inch hail and was reported with the storm that tracked across Weld County with rainfall estimated at 1.5 inches in the core. A CoCoRaHS station in the area recorded 1.18 inches, which is very impressive considering the fast storm motion. Another severe storm tracked east from Denver to Yuma County. It produced golf ball sized hail over Yuma County. The quick storm movement kept 1 hour rain rates around 1 inch, so no flooding was reported as of this morning.

To see estimated precipitation totals 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 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.

SPM 06-20-2019: A Break in Rainfall Allows Colorado to Dry Out

Issue Date: Thursday, June 20th, 2019
Issue Time: 10:00AM MDT

Summary:

After a couple days of widespread, heavy rainfall Colorado got a chance to dry out as northwest flow aloft pushed a dry, warm air mass over the state. High temperatures increased statewide with a ~10°F increase over eastern Colorado. Despite a drastic drop off in PW, enough residual moisture remained for some afternoon showers and weak thunderstorms over the western high terrains, Front Range and Northeast Plains. Maximum totals yesterday over the Northern and Central Mountains were just under 0.25 inches with most storms producing between 0.05 and 0.15 inches of rain. The strongest storm of the day was a weak thunderstorm that tracked into northern Weld County from Wyoming. With fast storm motion, only minimal rainfall occurred with radar estimating 0.25 inches of rain under its core. A CoCoRaHS station in Logan County recorded 0.22 inches from the storms and Sterling Airport recorded a wind gust of 24 mph.

The Areal Flood Warnings continued for the San Antonio and Conejos Rivers in southeastern Conejos County, the headwaters of the Rio Grande and in central Saguache County. Emergency management relayed minor flooding of lowland areas to the local NWS offices. Several Areal Flood Advisories also continued for the Central and San Juan Mountains with 10 gages in Action stage. Take a look at the gages here: AHPS Gages. Other than minor lowland flooding from high running rivers, flooding was not reported on Wednesday.

To see estimated precipitation totals 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 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.

SPM 06-19-2019: Another Day of Thunderstorms Statewide, With Continued Flood Warnings in the San Juan Mountains

Issue Date: Wednesday, June 19th, 2019
Issue Time: 10:13AM MDT

Summary:

Another wet day throughout the state yesterday as another shortwave propagated over the state from Utah. Rain began over the Northwest Slope and Grand Valley around 7am yesterday as the disturbance first entered the state, providing additional lift and vorticity to the upper elevations. Heavy rain reports were provided to the NWS in southern Routt County near Toponas and in Garfield County near Glenwood Springs measuring 0.59 and 0.57 inches respectively. Small hail of 0.25 inches and heavy rainfall of 0.54 inches was reported north of Cedaredge in Delta County. Other than these isolated cases, precipitation was light in nature, with showers until 7am today in the northwest quadrant of the state. Over the San Juan Mountains precipitation began midday. The high pressure system to the south perturbed moisture in the lower elevations and kept precipitation to the high country. Heavy rain was reported to NWS in San Miguel County near Telluride and La Plata County near Rockwood measuring 0.57 and 0.54 inches respectively. Due to lack of moisture and insufficient forcing as the low pressure system moved over the Eastern Plains, precipitation ended by 9PM.

Convection began on the Continental Divide around 10:30 as the shortwave began to influence the area. Ample moisture from the Eastern Plains, combined with upslope flow allowing heavy rainfall over the Front Range, with CoCoRaHS reporting 1.35 inches in Larimer County. Convection then moved off of the mountains to the ESE. Precipitation was lighter in the Northeast Plains compared to its southern counterpart due to cool temperatures and morning cloud cover, which lead to weakened convective instability. Convection began around 11:30 on the Palmer Ridge providing light rain to the Metro area. Additional systems developed over the Wet Mountains and progresses to the ESE, spawning reports of hail over Otero and Crowly counties. CoCoRahs stations in Baca County reported 1.05 inches of rain. Rain ended around 10PM last night over the Southeast Plains.

Flood warnings remain in effect for Mineral and Rio Grande Counties, Conejos County along the San Antonio and Conejos Rivers, and the Saguache Creek in Saguache County. No new flooding was reported yesterday.

For a look at yesterday’s precipitation, please see our 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.