Issue Date: Thursday, September 16th, 2021
Issue Time: 9:25AM MDT

— Flooding is NOT expected today

The water vapor image, below, shows that very dry air has overtaken a majority of the Four Corners region. This morning’s Precipitable Water (PW) at Denver and Grand Junction were at 0.38 and 0.42 inches, respectively, with a deep mixed layer residing above a very dry boundary layer. Additionally, winds have increased in the mid-levels of the atmosphere and with strong heating today, some of this momentum will mix down to the surface. The takeaway is, for the majority of the state, we expect temperatures to run well above normal with breezy/windy conditions and no precipitation. With drying soils, this recipe equates to an enhanced threat for wildfire generation, and a Red Flag Warning and Fire Weather Watch have been posted for the higher terrain of central and northern Colorado.

The lone region that could experience some meaningful precipitation is the far northeast corner of the state. As a strong trough to the north guides a cool front into Colorado overnight, the synoptic-scale lift will overcome the modest moisture to produce a line of broken showers and storms. A few storms could even become severe (mainly strong wind threat). However, with the relatively swift storm motion, flooding is NOT expected today.

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:

Northeast Plains:

Sunny and hot through the late afternoon, then isolated to scattered showers and storms possible especially towards the NE/KS border. Max 1-hour rainfall up to 0.8 inches, along with a threat of severe weather. However, flooding is NOT expected today.

Primetime: 7PM through Midnight

Palmer Ridge, Front Range, Urban Corridor, Southeast Plains, Northern Mountains, Northwest Slope, Southwest Slope, Grand Valley, Central Mountains, San Juan Mountains, San Luis Valley, Raton Ridge and Southeast Mountains:

Becoming partly cloudy and very warm with breezy conditions developing in the afternoon. A Red Flag Warning has been posted for the Northwest Slope and Northern Mountains, along with a Fire Weather Watch for parts of central Colorado.

A cool front overnight could trigger an isolated rain or snow shower over the highest peaks of the Northern Mountains.

Flooding is NOT expected today.

Issue Date: Wednesday, September 15th, 2021
Issue Time: 9AM MDT

— Flooding is NOT expected today

Outside of some fog and cloud cover over the eastern border counties, it’s a clear and cool start to the morning. North and northwest flow has pulled in a dry air mass across the state, which is helping to produce the clear skies seen in the visible satellite imagery below. As anticipated, PW over Grand Junction and Denver has dropped to under a half inch with the dry air overhead. With subsidence behind the departing trough and a very dry atmosphere, rainfall is not expected today. The sinking air will also help to increase high temperatures when compared to yesterday, so expect above average temperatures to return. Flooding is NOT expected today.

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:

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

Afternoon temperatures will be on the rise, and highs in the upper 80Fs to low 90Fs are forecast for the lower elevations. Over the mountain valleys, highs should reach into the upper 70Fs to low 80Fs. Rainfall is not anticipated today, so be sure to get out and enjoy the blue skies and limited smoke over the state.

Northeast Plains, Southeast Plains, Urban Corridor, Raton Ridge, San Luis Valley, Front Range, Southeast Mountains & Palmer Ridge:

Even with the cool down yesterday, temperatures are expected to quickly rebound this afternoon. Highs over the I-25 Corridor will reach into the upper 80Fs and possibly reach 90F. Over the plains, 90Fs are forecast south with upper 80Fs over the central and northern plains. Mountain locations should reach into the uppers 70Fs with low 80Fs forecast for the SLV. Rainfall is not anticipated today, and the cloud cover and fog over the plains should dissipate with a little daytime heating.

Issue Date: Tuesday, September 14th, 2021
Issue Time: 9:50AM MDT

— A LOW flood threat has been issued for the Northeast Plains, Palmer Ridge, Southeast Plains and Raton Ridge

A cold front passed through the state last night, which lead to much cooler morning temperatures across the northern tier of the state this morning. There is still a little bit of upper-level lift helping to generate some weak showers just east of Denver and over Yuma County. Today, post-frontal upslope flow is expected to generate a batch of afternoon storms over the eastern mountains and Palmer Ridge, which should track east and southeast into the adjacent plains by early afternoon. PW, behind the front, has increased to 0.77 inches in Denver with an increasing gradient eastward, over the plains. The higher surface moisture, marked below, should be reinforced by easterly surface winds on the north side of the surface Low. This should allow storms to grow in coverage and intensity as they track into the eastern plains. With decent shear in place from northwesterly flow aloft, a couple severe thunderstorms will be possible with the main threats being large hail and strong outflow winds. These would most likely occur along and south of I-70 and east of I-25 over the Southeast Plains and eastern Palmer Ridge; however, an isolated storm could break the cap over the far Northeast Plains as well with enhanced lift over the area. Steering flows should be just quick enough that widespread flooding issues should be avoided, but local, heavy rainfall may still be possible in the stronger storm cores that can develop. For this reason, a LOW flood threat has been issued.

Over western Colorado, flow aloft will turn more northwesterly throughout the day, which will begin to pull in a dry air mass from western Wyoming and northern Utah. Between this, the already dry boundary layer and an increase in stability behind the passing trough, rainfall is not anticipated for the lower elevations. A couple isolated, high-based storms will still be possible over the Central and San Juan Mountains near the Continental Divide, but flooding is not expected over these regions.

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:

Front Range, San Juan Mountains, Southeast Mountains & Central Mountains:

Scattered weak storms should develop over the mountains this afternoon favoring the southern Front Range and Southeast Mountains for development. With a dry boundary layer, storms should be rather weak in nature and may produce some strong outflow winds. Max 1-hour rain rates up to 0.25 inches will be possible, but most storms are expected to produce under 0.15 inches of rainfall. Flooding is NOT expected.
Primetime: 1PM to 9PM 

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

Better moisture, lift and instability are forecast over these regions, although it looks like most of the Urban Corridor will be capped as well as areas north of the front (Northeast Plains). A couple severe thunderstorms will be possible this afternoon with the main threats being damaging outflow winds and large hail. Local, heavy rainfall will be possible in the storm cores, so a LOW flood threat has been issued. Max 1-hour rain rates up to 1.10 inches (west) and 1.75 inches (east) are possible. This could cause road flooding, local creek/stream flooding as well as field ponding.
Primetime: 2PM to 11:30PM

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

Flooding is NOT expected today, nor is any rainfall. Cooler temperatures are forecast, especially north where valley locations should stay in the upper 70Fs to low 80Fs. Over the Grand Valley and south, lower elevations should be in the mid to upper 80Fs.

Issue Date: Monday, September 13th, 2021
Issue Time: 9:55AM MDT

— Flooding is NOT expected today

Whenever there are morning clouds across Colorado during the warm season, chances are something interesting is occurring weather-wise. As shown in the visible satellite image, below, such is the case today. A strong jet streak is positioned just west of Colorado, embedded within a nearly zonal flow aloft. A pronounced shortwave disturbance was noted along the WY/CO border on the eastern edge of the jet streak. This disturbance will move quickly eastward today, while the jet streak will continue to act as a wave-maker and produce other weaker disturbances in the atmosphere overhead. Despite the favorable dynamics, the main limiting factor to rainfall generation today is moisture. Precipitable Water (PW) was a meager 0.51 inches in Denver, but a bit higher at 0.73 inches at Grand Junction this morning. However, the moisture profile today once again suggests a boundary layer that will be too dry to produce heavy rainfall. Nonetheless, the strong dynamics will be able to generate some thunderstorms today mainly over northern Colorado, where the better dynamics are located. However, coverage will be lower than observed on Sunday. A few severe storms will once again be possible mainly over northeast Colorado, even later into the evening as surface winds are expected to turn easterly in response to a diurnal surface low pressure expected to develop over the Arkansas River basin. Ultimately though, the lack of moisture coupled with strong steering winds will limit point rainfall, and flooding is NOT expected today.

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:

Palmer Ridge, Front Range, Urban Corridor, Northeast Plains, Southeast Plains, Northern Mountains and Northwest Slope:

Partly to mostly cloudy, breezy and slightly cooler with isolated to scattered showers and storms possible, beginning early afternoon and lasting through the early overnight hours (mainly over the Northeast Plains). Max 1-hour rainfall up to 0.4 inches (west of I-25), and 0.7 inches (east of I-25). Flooding is NOT expected today. However, severe weather, mainly in the form of strong straight-line winds, is possible this afternoon with stronger storm cells.

Primetime: 1PM through 2AM

Southwest Slope, Grand Valley, Central Mountains, San Juan Mountains, San Luis Valley, Raton Ridge and Southeast Mountains:

Sunny to partly cloudy, breezy and hot today with an outside chance of a stray shower or weak storm across northern parts of the area. Max 1-hour rainfall up to 0.2 inches. Flooding is NOT expected today.

Primetime: 1PM through 9PM