Issue Date: Sunday, August 25th, 2019
Issue Time: 9:25AM MDT

Summary:

Afternoon cloud cover with some light sprinkles were all the passing shortwave and daytime diurnal pattern could muster for rainfall over the mountains yesterday. Better moisture over the Southeast Plains (Baca, Prowers and eastern Las Animas Counties) allowed for the only measurable rainfall of the day. MetStorm estimates just under 0.5 inches of rain fell with these systems with no observations in the area having significant amounts of precipitation recorded. Additionally, 1 inch diameter hail was also reported near Pritchett, CO associated with the severe thunderstorm. At 10:15AM yesterday, NWS Goodland issued an Areal Flood Warning for Cheyenne County with Cheyenne Creek running over County Road 9 at Wild Horse from Friday’s rainfall. An additional heavy rainfall report of 5.75 inches was submitted near Wild Horse after the SPM was published yesterday. The Areal Flood Warning was not renewed, so it’s probably safe to assume the high water has retreated.

High temperatures reached 97°F over Grand Junction and 95°F over Trinidad, which are much warmer than climatology. The Denver Metro region was right around 90°F with the valleys in the mountains nearing 80°F. Dense fog formed over the eastern plains last night, but ASOS stations are already showing the fog thinning over the last hour or so.

To see estimated precipitation totals over your neighborhood over the last 48-hours, scroll down the State Precipitation Map below.

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Issue Date: Saturday, August 24th, 2019
Issue Time: 9:55AM MDT

Summary:

As anticipated yesterday, when storms moved east of the dryline they produced some very heavy rainfall. Upper air dynamics with the passing trough enhanced the area of lift for storms to form, so storms over the eastern plains were very widespread when compared to the previous days. A Severe Thunderstorm Watch was issued around 3:30PM over the eastern plains with storms following shortly after. Storm motion was to the east and decreased as storms moved in this direction, so the heaviest rainfall was over the far eastern plains. Storms were a little pulse-like and back building, so they were able to sit over an area for a longer period, which increased totals. Storms moved east of the state just after midnight.

With the placement of the surface low, high moisture was reinforced over the northern Colorado border, thus as storms moved off the northern Front Range and combined with storms coming off the Cheyenne Ridge, they produced some very heavy rain. Max 1-hour rain rates up to 1.5 inches were estimated by MetStorm and hail up to 2 inches was also reported. The heaviest rain was over Cheyenne and Kit Carson County where radar estimated just over 3.5 inches. There was a report of 2.5 inches of rain in about 2 hours over Aroya and another report of 1.25 inches of rain near Seibert that fell in a 30 minute span. With these severe thunderstorms there was also a brief tornado reported near Kit Carson and hail up to 1.75 inches. Two Flash Flood Warnings were issued after 6PM with a flooding report in Kit Carson as “water ran like a river through the yard and almost up to the porch.”

To see estimated precipitation totals over your neighborhood on Friday, scroll down the State Precipitation Map below.

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Issue Date: Friday, August 23rd, 2019
Issue Time: 10:15AM MDT

Summary:

Another round of isolated severe thunderstorms over eastern Colorado on Thursday. While moisture dropped off near the eastern mountains, due westerly flow aloft mixing out moisture to the east, enhanced lift from the approaching trough caused some cloudy afternoon skies and enhanced storm coverage. Afternoon upslope flow generated storms over the Front Range, Southeast Mountains and western Palmer Ridge around 2PM, which moved into the adjacent plains by mid-afternoon with westerly steering flows. Storms were moving fairly fast, and high-based to the west, but they were still able to drop some decent accumulations. As they moved east, their rainfall rates increased due to the higher moisture content of the atmosphere.

A Flash Flood Warning was issued over the Spring Creek burn area at 4:30 PM with 1-hour rainfall totals estimated at 0.33 inches from MetStorm before the bias correction. There was an observation of 0.36 inches in La Veta, but as of this morning, there was no flooding reported near the burn area. Another storm in El Paso County near Garden of the Gods produced nickel sized hail and storm totals close to 0.2 inches (USGS gage at Douglas Creek). The USGS gage, Cheyenne Creek at Evans, observed 0.67 inches, which is slightly south of the hail report. As these storms moved west, they dropped up just under 1.5 inches over southern Lincoln County with CoCoRaHS stations in the area recording between 0.67 and 0.97 inches. An outflow boundary kicked off an additional storm over southern Yuma County were radar estimated up just over 2 inches fell.

To the north over Weld County, a little better moisture held on near the CO/WY/NE border. A storm that formed over the Cheyenne Ridge merged with another storm coming off of the northern Front Range. This storm ended up dropping an estimated 2.25 inches over a small area, and a MesoWest station near Sterling picked up 0.68 inches from this same storm as it moved east. Note this storm ran into a cap over the northeast corner, so it quickly weakened east of Logan County. Thankfully, no more than 1 inch hail was reported with this storm. Right before the storm merged, a weak tornado was reported near Roggen in Weld County (between Wiggins and Hudson on I-76), which lasted for 6 minutes. NWS will be doing a follow up report to confirm this tornado sometime in the next couple of days.

Back to the west there were a couple of rounds of brief showers over the San Juan Mountains and near the Continental Divide. The approaching trough brought increased lift to the area, so there was a bit more cloud cover to help with the heat over higher terrains. Storms yesterday were once again high-based, so the rainfall remained light. MetStorm indicates most totals over the San Juan Mountains were under 0.1 inches with a couple reports near 0.15 inches. Evaporation of the storms also caused some brief, gusty winds in addition to stronger surface winds from the tightening gradient. Not surprisingly, there was a Red Flag Warning over the Northeast Corner, though it is likely critical fire weather might have been reached over small areas of the high terrains as well. Winds gusts yesterday (thunderstorm and non-thunderstorm) ranged from 45 to 55 mph with sustained winds near 15mph over the Northwest Slope.

To see estimated precipitation totals over your neighborhood on Thursday or for the last 72-hours, scroll down the State Precipitation Map below.

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Issue Date: Thursday, August 22nd, 2019
Issue Time: 10:15AM MDT

Summary:

Quite a bit of moisture in the atmosphere after the passage of a cold front early Wednesday morning. Post frontal upslope flow in this moisture rich environment, with slow steering winds, set the stage for pockets of heavy rainfall. Strongest storms popped up where there was the best break in cloud cover. Rainfall began first to the south over the eastern mountains, then to the north where it took a little longer to erode the cap. Several flood advisories were issued beginning at 1PM and ending at 10:15PM with one Flash Flood Warning issued for Denver at 6:40PM. Storms yesterday were nearly stationary with outflow boundaries and back building storms helping set off more storms over the same area. There were also two flood advisories issued for the Spring Creek and Junkins burn areas, but flooding was not reported. MetStorm indicates just over 0.5 inches and 0.25 inches fell, respectively, which are below known flash flooding rate criteria. A Severe Thunderstorm Warning was issued for the Front Range, Urban Corridor, Palmer Ridge and portions of the Northeast Plains at 4PM, so plenty of warning before the storms struck.

Denver had a whopper of a storm just after rush hour that lasted over an hour, caused intermittent power outages and flooding of low-lying intersections. Quite a bit of lightning with it, too along with 1 inch hail. The highest ALERT gage (I-25 and 6th Ave) indicated up to 1.9 inches of rainfall though this gage may have been slightly contaminated by hail as totals nearby were not this high. The highest area of rainfall looked to be near Wings Over the Rockies where gages had between 1.1 and 1.5 inches of rainfall over a fairly large area. The Cherry Creek gage briefly reach Action Stage (below). To take a look for yourself, click here and change options (top left) to 24-hour rainfall: http://alert5.udfcd.org/LDAD/gmapV3.html

Further south, over Fremont County, there was also some heavy rain where MetStorm indicates up to 1.25 inches fell. The cap never did break over the Southeast Plains, so the anticipated heavy rainfall threat never materialized over this region. Although there were totals up to 1.25 inches over Las Animas County, which was in the Low threat area. Storms also moved in over Yuma County from the panhandle, which dropped between 2 and 2.5 inches in its core. There were no official LSRs (Local Storm Reports) this morning, although flooding was confirmed by several Twitter users.

To see estimated precipitation totals over your neighborhood on Wednesday, scroll down the State Precipitation Map below.

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