SPM 07-04-2020: Heavy Rainfall Coverage Expands Across the Eastern Plains as Steering Flows Slow

Issue Date: Saturday, July 4th, 2020
Issue Time: 10:10AM MDT

Summary:

Higher dew points over the eastern plains yesterday help produce more widespread thunderstorm coverage. Storms had very slow steering winds, so they were able to produce extra rainfall over the areas they tracked across; especially east. Southwest Yuma County got hit again. The same WxUnderground gage from yesterday (south of Joes) showed 1.33 inches, whereas MetStorm had 1.50 inches. So, QPE estimations might be slightly overestimated again. If you’re keeping track, that’s a 48-hour total just over 2 inches for that station! Kit Carson County got hit again, and the coverage of wetting rain was greater than Thursday. There was a Flash Flood Warning issued for the thunderstorm complex just before 8PM as cars were hydroplaning off I-70. Gusts around 60 mph were also recorded with these storms, and hail up to 1.75 inches. There were a couple other Flash Flood Warnings over Yuma and Cheyenne County from NWS Goodland. No Flash Flood Warning was issued for Kiowa County despite storm totals being estimated at 3.50 inches. A WxUnderground station SE of Sheridan Lakes recorded 1.92 inches in the area of 3 to 3.50 inches in the QPE below, so totals were likely overestimated. Still, that’s quite a bit of rainfall!

Back west over the mountains, scattered totals were just under 0.50 inches with a lot of SNOTELS around 0.40 inches. There was a report of 0.54 inches of rain in Leadville for the 24-hour period. It was a bit too dry for much wetting rain in the western high county. More gusts than rainfall were reported with 45 mph gusts recorded over the Grand Valley. Outside of the hydroplaning, flooding was not reported as of this morning.

For precipitation estimates in your neighborhood over the last 24 to 72-hours, scroll down to the State Precipitation Map below. Note that the 72-hour QPE has some errors over the San Luis Valley. However, using the non-bias corrected QPE would really inflate totals from yesterday. Over Yuma and Kit Carson County, 48 and 72-hour totals are likely inflated as I’ve shown QPE was likely overestimated the last couple of days compared to observations in the area.

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 07-03-2020: Heavy Rainfall Over Kit Carson County

Issue Date: Friday, July 3rd, 2020
Issue Time: 10:40AM MDT

Summary:

Storms fired along a moisture boundary over the eastern plains yesterday. It was a battle between instability/moisture and the developing trough, which was mixing the severe weather ingredients eastward. Higher moisture remained over the Northeast Plains just to the north of the surface low. Storms were barely moving, so they produced some heavy rainfall as well as damaging hail. As far as storm reports, there were several tornadoes reported over Washington and Kit Carson County. These were likely weak landspouts as upper dynamics were not great for tornado formation. Additionally, storm chasers reported 2.75 inch hail (baseball size) over Washington County! I can only image the damage that did to crops and property.

The heavy rainfall cores were rather small in size, but some impressive rainfall totals came out of the storms. The COAGMET station near Joes, CO recorded 1.23 inches and another nearby WxUnderground station recorded 0.71 inches. So, the QPE estimates of rainfall over southwest Yuma County are likely overestimated below. Twitter videos and CDOT cams reported some minor flooding in fields and parking lots near Burlington. MetStorm Live shows 2.5 inches of QPE over Burlington, CO. A CoCoRaHS in town recorded 1.9 inches over the same area, so the QPE estimates are likely high over this area as well. Additionally, the COAGMET station in Burlington recorded 0.66 inches in an area that is estimated at 1.5 inches. The Burlington Carson County Airport recorded 3.38 inches for the 24-hour period just south of town, which is likely driving the QPE for MetStorm. There were several hail reports in the area, so I’m wondering if this gage wasn’t contaminated by it? I would have expected a lot more flooding if that was the case as well. QPE from AHPS has between 1.5 and 2.0 inches in this same area and MRMS has about 3 inches. Overall, I think these numbers are bit high after looking at observations, so take the QPE below with a grain of salt.

For precipitation estimates in your neighborhood over the last 24 to 72-hours, 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 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 07-02-2020: Beautiful Day in the Neighborhood

Issue Date: Thursday, July 2nd, 2020
Issue Time: 9:45AM MDT

Summary:

Absolutely gorgeous summer day on Wednesday as temperatures started to rise behind the trough. Below is the satellite imagery for the state at 3PM (source: College of DuPage) – crystal clear conditions with a few fair-weather cumulus over the mountains. Isolated storms may have produced trace amounts of rain (sprinkles, really), but the more likely scenario is just some cloud cover. Fog rolled into the easterly plains overnight with southeasterly surface flow increasing surface moisture. This moisture plume can be seen over Kansas working its way east below. Burlington reported ¼ mile visibility this morning around 5AM. The foggy conditions are continuing to improve with a little day time heating and mixing.

Below is the new drought map that came out this morning, and it is valid as of June 30 (Tuesday). This is the first map with D4 (Exceptional Drought) conditions, which are present over Baca County. The D4 category was last seen in February of 2019 after a dry WY 2018. Unfortunately, rainfall this afternoon will do little to help the worsening situation over the eastern plains. Baca County is about 3 – 3.75 inches below normal precipitation over the last 3 months. The D3 (Extreme Drought) area has also expanded over the Southeast Slope as well. Northern Colorado continues to remain the only area without drought conditions.

For precipitation estimates in your neighborhood over the last 72-hours, 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 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.

Note: The 24-hour, 48-hour and 72-hour total precipitation do not contain bias corrections today due to errors in the CoCoRaHS data. This means there may be underestimations in QPE over the southwest and southeast corners of the state.

SPM 07-01-2020: Rainfall Along the Jet & Scattered Storms for the Northeast Plains

Issue Date: Wednesday, July 1st, 2020
Issue Time: 9:45AM MDT

Summary:

Light rainfall developed along the jet in a north/south oriented band on Monday night, so the Front Range started the morning with some brief showers. Storms generally produced between 0.10 (Boulder) and 0.32 inches (Fort Collins) along with some graupel due to the colder temperatures behind the front. This may have inflated some of the totals in the gages, but these amounts seem reasonable and replicated at more than one site. Light snow was also reported earlier in the morning/Monday night at the highest elevations along this same band. The eastward moving band of showers lifted north with the jet by midday. Additional scattered afternoon storms developed over the Palmer Ridge and expanded in coverage as the moved in the Northeast Plains where a little better moisture remained. Totals just under 0.50 inches were reported in the storm cores. A brief storm also popped up over Morgan County, but observations in the area indicate very little rainfall reached the ground. Overnight lows got chilly with Alamosa dropping to 30F – that is a new daily record low and ties the all time monthly (July) record. Lows were only forecast to drop to 38F.

For precipitation estimates in your neighborhood over the last 24 to 72-hours, 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.