Issue Date: Monday, June 22nd, 2020
Issue Time: 9AM MDT

— Flooding is NOT expected today

Northerly flow aloft will be in place over the state today, which will help keep highs a little cooler than they normally would be. Below you can see the mid-level moisture over the state, which is strongest over eastern Colorado. The 500mb High to our southwest is expected to strengthen, which will move the marked jet stream, over eastern Colorado, into Kansas/Nebraska throughout the day. Although it may look moist below, it is much drier at the surface with dew points around and below 30F over western Colorado. This should limit the precipitation chances over the area, but a couple high-based afternoon showers will still be possible over the western mountains near the Divide.

Dew points over eastern Colorado range from mid-40Fs (west) to mid-to-upper 50Fs (east), and it is expected that some of the surface moisture (west) will mix out throughout the day. There should be enough remaining moisture under the building ridge for some weak, high-based showers and thunderstorms to form over the Front Range, Palmer Ridge, and Southeast Mountains with afternoon, upslope flow. The highest coverage is expected to be over the southern Front Range/Palmer Ridge intersect with light rainfall forecast over the mountains/urban corridors and moderate rainfall possible over the Palmer Ridge. As storms move southeast with the steering flow, the will move into higher dew points over the Southeast Plains as a surface low is forecast to develop just south of that area in northern New Mexico. This will intensify the storms and may allow a weak, severe thunderstorm or two to form over the Southeast Plains (Baca and eastern Las Animas Counties). Rainfall rates are expected to remain below the 1.50 inch flood threat criteria, so flooding is not forecast. A couple light, lingering showers are possible tonight east of I-25 and south of I-70 as mid-level energy (shortwave) moves through the northwest flow.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

Southeast Mountains, Front Range, Palmer Ridge, Southeast Plains, Northeast Plains, & Raton Ridge:

It should remain dry over the Northeast Plains this afternoon due to storm motion and low dew points. Best moisture will be over the Southeast Plains, Raton Ridge, and Palmer Ridge. Therefore, moderate rainfall may be possible with max 1-hour rain rates up to 0.60 inches possible over the ridges. Over the far southeast corner, max 1-hour rain rates up to 1 inch will be possible with severe hail under the strongest cores and brief, gusty winds. Over the Front Range and immediate adjacent plains, totals will be closer to 0.25 inches under the stronger storms with lower rain rates for the Southeast Mountains. Therefore, flooding is not anticipated. Reminder that there may be a couple light, lingering overnight showers over the Southeast Plains.

Primetime: 1PM to 12AM

Central Mountains, San Juan Mountains, Northern Mountains, Northwest Slope, Grand Valley, San Luis Valley, & Southwest Slope:

Best chance for rainfall will be near the Divide over the Central and San Juan Mountains. Storms will most likely produce virga with the dry boundary layer promoting evaporation, but light rainfall could reach the ground over the San Juan Mountains. A Red Flag Warning has been issued for the Southwest Slope due to northwest winds in the 10 to 20 mph range this afternoon (gusts to 30) and relative humidity dropping into the teens. See NWS Grand Junction for the latest.

Issue Date: 6/21/2020
Issue Time: 8:15 AM

— Flooding is NOT expected today

Summer-time warmth is the headline of today’s weather act, with high temperatures near yesterday’s highs. Different from yesterday, however, is a disturbance that will scrape across Colorado, providing the opportunity for a few isolated-to-widely scattered thunderstorms this afternoon and evening. Moisture remains limited in the low-levels of the atmosphere, so any storm activity is expected to produce more gusty winds than rain. The best chance for measurable precipitation will be in the High Country regions of the Northwest Slope, Northern Mountains, Central Mountains, and Front Range, as well as near the northern CO border in the Urban Corridor and Northeast Plains regions. For the rest of the Urban Corridor/Northeast Plains, Palmer Ridge, Southeast Mountains, Raton Ridge, and Southeast Plains regions, very little precipitation is expected to reach the surface.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. Hover over the threat areas for more details and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts

Urban Corridor, Palmer Ridge, Northeast Plains, Southeast Plains, and Raton Ridge:

Summertime warmth is the main weather story today, with high temperatures near yesterday’s highs. A few isolated-to-widely scattered thunderstorms will rumble during the afternoon and evening hours, producing more gusty winds than rain. The best chance for measurable precipitation will be along the northern CO border. Rain rates are expected to be less than 0.2 inches/hour.

Timing: 2 PM – 10 PM

Front Range, Southeast Mountains, Northwest Slope, Northern Mountains, Central Mountains, Grand Valley, Southwest Slope, San Juan Mountains, and San Luis Valley:

Isolated-to-widely scattered thunderstorms will rumble today/tonight, with the best coverage over the Northwest Slope, Northern Mountains, Front Range, and Central Mountains regions. Lesser coverage is expected elsewhere, with chances diminishing the further southwest you go. Any storm activity will produce more wind than rain, with the best chance of measurable precipitation over the Northwest Slope, Northern Mountains, Front Range, and Central Mountains regions. Rain rates are expected to be less than 0.15 inches/hour.

Timing: Noon – 10 PM

Issue Date: 6/20/2020
Issue Time: 8:00 AM

— Flooding is NOT expected today

Warmer and drier is the name of the weather game today, as upper-level high pressure builds in across the western United States. High temperatures will be near normal for the first day of Summer, with skies remaining mostly sunny throughout the day. There exists a *small* chance (less than 10%) for an isolated thunderstorm or two near the eastern CO border during the afternoon hours, but even in the event one forms, it will quickly leave the state, providing almost no impact to Colorado. As the afternoon turns toward the evening hours, a pocket of upper-level moisture will move into the state from the northwest, increasing cloud cover for the overnight hours, especially over the High Country.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. Hover over the threat areas for more details and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts

Urban Corridor, Palmer Ridge, Northeast Plains, Southeast Plains, and Raton Ridge:

Sunshine and warmer temperatures will mark the first day of summer, with highs in the 80s for most and into the 90s for portions of the Southeast Plains. There is a less than 10% chance for an isolated thunderstorm or two near the eastern CO border this afternoon, but little-to-no impacts are expected from any activity.

Front Range, Southeast Mountains, Northwest Slope, Northern Mountains, Central Mountains, Grand Valley, Southwest Slope, San Juan Mountains, and San Luis Valley:

Mostly sunny and warmer conditions will usher in the Summer season, with high temperatures ranging from the 80s and near-90 degrees for lower valleys to the 50s and 60s for higher elevations. Increased cloud cover will build in from the northwest during the late afternoon/evening, sticking around for much of the overnight hours.

Issue Date: Friday, June 19th, 2020
Issue Time: 9:45AM MDT

— A MODERATE flood threat has been issued for the Southeast Plains and portions of the Northeast Plains, Urban Corridor, Palmer Ridge

— A LOW flood threat has been issued for the northern Southeast Mountains and eastern Raton Ridge. This includes the Decker burn area.

Another cool start to the day with most of the state waking up to cloudy conditions. As of 7:30AM, snow was being reported at La Veta Pass! There were also reports of rain and fog over the mountains, which is due to mid-level lift out in front of the base of the trough and an upper level jet. Behind this area of lift, drier conditions are forecast, which can be seen by the cloud free conditions over western Colorado. Rainfall is not forecast behind the vorticity maximum (orange “X”). The visible imagery also shows how moist it is over eastern Colorado with a large cloud deck in place. PW over Denver was measured at 0.60 inches, but higher values are present over Southeast Colorado.

Today, the area of lift/storms (orange “X”) will move eastward and intensify as they move into the moisture rich environment just off the foothills (southwesterly surface flow). It looks like a little moisture may scour out westward over Northeast Colorado, but heavy rainfall is still anticipated over the eastern portion of the metro area due to lower storm motions (10 to 15 mph to the west) and trailing thunderstorms. A few breaks in the cloud cover east will also help intensify the storms, so a Moderate flood threat has been issued for the eastern metro area/Palmer Ridge.

Storms will likely become severe as they move into regions with more widespread, cloud-free conditions due to better instability being able to build. This is most likely to happen over the Southeast Plains where the cloud deck isn’t quite as thick, and there are already breaks in the cloud over this area (see image above). Severe thunderstorm threats include large hail and strong winds. Dew points over southeast Colorado will be just over 50F, so heavy rainfall is also anticipated with the severe thunderstorms that form. Most of the thunderstorms that form today will roll into Nebraska and Kansas by 9PM, but a few lingering overnight storms are possible over the far Southeast Plains border counties. This is why the Moderate flood threat has been extended south.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

Southeast Mountains, Southeast Plains, & Raton Ridge:

Over the Southeast Mountains, storm coverage won’t be quite as widespread as the Front Range. Max 1-hour rain rates up to 0.50 inches will be possible near the Decker burn area, so the Low flood threat has been extended back to capture this. A couple storms will likely form on the Raton Ridge as well. Rain rates will increase as storms move off the mountains and reach the I-25 corridor with max 1-hour rain rates up to 1.1 inches possible, so a Low flood threat has been issued. A severe storm or two is possible in areas where cloud’s break, which will likely be further east over the Southeast Plains. Paired with high moisture, max 1-hour rain rates up to 1.75 inches will be possible, so a Moderate flood threat has been issued. Additional overnight storms are possible over Baca and Prowers Counties, and in a moisture rich environment, 24-hour totals could reach values greater than 2 inches. Thus, the Moderate threat has been extended south.

Primetime: 12:30PM to 3AM

Front Range, Northeast Plains, Urban Corridor, & Palmer Ridge:

Storms are not expected to be as severe over these regions due to higher cloud cover and cooler temperatures (lower instability). Max 1-hour rain rates up to 0.75 inches will be possible over the southern foothills and western metro area. A quick 0.50 inches in 30 min could cause flooding issues over the impervious surfaces, so a Low flood threat has been issued. Up north, max 1-hour rain rates drop off a little more due to slightly lower moisture in the area, but a good wetting rain is still coming your way. Dew points looks to increase just east of the I-25 corridor in the southern Urban Corridor, so trailing storms and increased convergence on the higher elevation of the Palmer Ridge could produce 1 to 2-hour totals up to 1.25 inches in the moisture rich environment. Thus, the Moderate flood threat for the area. Storms should exit the Moderate flood threat region by late afternoon. Out east, totals will generally be between 0.75 and 1.25 inches.

Primetime: 12:30PM to 9PM

Central Mountains, San Juan Mountains, Northern Mountains, Northwest Slope, Grand Valley, San Luis Valley, & Southwest Slope:

After this morning’s mountain rainfall, these regions will move into the dry slot, and that will be the end of the rainfall for this system. Highs over the valleys will reach into the 80Fs, so it should be a pleasant day. An Air Quality Alert remains in place over the southwest corner, and the approaching trough will likely increase surface winds over this area. Thus, a Red Flag Warning is issued for westerly winds in the 10 to 20 mph range (gusts to 30 mph) and relative humidity dropping into the teens and single digits.