Issue Date: Monday, August 29th, 2022
Issue Time: 10:30 AM MDT

— Flooding is NOT expected today

A ridge of high pressure is currently situated over western Utah this morning and is continuing to wrap drier air into Colorado with northwest flow. A few weak impulses are noted in the flow and are marked by the “X’s” in the visible satellite image below. The southeastern impulse that is responsible for this morning’s light showers over the plains will continue to move out of the state, and will be followed by another weak impulse to the north. As the northern impulse moves through the flow, it may trigger an isolated storm or two over the high terrain south. However, rising pressure across the state should promote subsidence, helping to limit rainfall chances. Moisture is also expected to be quite limited today, as in prior days, with Grand Junction measuring PW of 0.67 inches and Platteville measuring PW of 0.56 inches this morning. Dew points are typically in the mid-30s in the mountains and upper 40s°F across lower elevations, with low to mid-50s°F noted over the far eastern plains this morning. Later today, instability is forecast to be highest across the southeastern border counties with values ranging from 750-1000 J/kg of CAPE forecast this afternoon. With northerly steering flow and warmer temperatures aloft, along with marginal boundary layer moisture, any storms that can develop should be of low intensity. In addition to producing brief rainfall, storms may produce lightning and gusty winds. NO flooding is 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:

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

Slightly cooler temperatures are forecast today behind the passage of a weak cold front. This afternoon, isolated storms may develop over the southern Southeast Mountains and adjacent plains producing light to moderate rain rates up to 0.25 inches over a 30-to-45-minute span. Over the far southeast border counties of the Southeast Plains, where slightly higher moisture may exist, rain rates up to 0.6 inches over the same time span may be possible. However, subsidence is strong today, so storm potential is low and those that can develop shouldn’t last long. Elsewhere, clear skies and mainly dry conditions should be predominant for eastern Colorado today and NO flooding is expected.

Primetime: 2PM to 7PM

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

A few stray high clouds were noted across portions of the Southwest Slope and mountains this morning, otherwise the clear and dry conditions should continue. Given the negligible moisture and increasing subsidence, storms are unlikely for western Colorado and NO flooding is expected today.

Issue Date: Sunday, August 28th, 2022
Issue Time: 10:35 AM MDT

— Flooding is NOT expected today

A weak disturbance currently located in the central part of Colorado is expected to exit the state today, followed by another disturbance moving in from the west from Utah, which is marked by the “X” in the water vapor image below. These mid-level dynamics are expected to trigger isolated to widely scattered storms across the western half of the state today. The most notable change in the forecast today from prior days, and the greatest hindrance to storms, is the sharp decrease in moisture throughout Colorado.

Grand Junction measured PW was 0.80 inches, a slight moistening from yesterday, while Platteville measured a significant drop in column moisture with a PW of 0.46 inches; this indicates a very sharp moisture gradient from west to east across the state. Additionally, surface dewpoints in the upper 30s to low 40s°F indicate boundary layer moisture has also dropped significantly from yesterday over eastern Colorado. Given negligible instability over eastern Colorado, most storms should be confined to the mountains west of the Continental Divide this afternoon. However, with weak forcing from the aforementioned disturbance, some elevated showers and weak storms may drift into the eastern plains this afternoon and produce primarily gusty winds with only limited rainfall accumulation.

Further west, both column and boundary layer moisture are slightly higher with surface dew points averaging in the mid-40s°F. Instability values are forecast to reach between 500-1000 J/kg of CAPE this afternoon across parts of western Colorado. Combined with the added energy from the incoming mid-level dynamics, this will provide enough added lift to trigger widely scattered storms over primarily higher elevations of western Colorado this afternoon. The combination of greatest depth of moisture and instability is forecast to be over the central and southern San Juan Mountains and is thus where the isolated heaviest downpours will be possible with the stronger storms this afternoon. Still, rain rates are expected to remain below flood thresholds 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:

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

Some scattered clouds and a few isolated weak rain showers are ongoing across portions of western Colorado this morning. By early afternoon, isolated to widely scattered storm development is likely along and west of the Continental Divide. This rainfall is expected to be mostly light to moderate in intensity except over portions of the higher elevations of the Central Mountains, San Juan Mountains, and eastern Southwest Slope. Isolated max 30-to-45-minute rain rates up to 0.4 inches will be possible for the Northern Mountains and Northwest Slope, and up to 0.6 inches will be possible for the Central Mountains, Southwest Slope, and San Juan Mountains. Gusty winds, lightning, minor field ponding, and light runoff over steep terrain may occur, but NO flooding is expected today.

Primetime: 1PM to 9PM

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

Skies are mostly clear this morning for eastern Colorado aside from a few stray high clouds. By early to mid-afternoon, a few isolated to widely scattered rain showers or weak storms are expected to develop over the Front Range and Southeast Mountains and drift into the adjacent foothills. Max 30-to-45-minute rain rates up to 0.4 inches will be possible for the southern Urban Corridor and Palmer Ridge, and up to 0.6 inches for the southern Front Range and the northern Southeast Mountains. These storms should be quicker moving relative to the western half of the state due to faster steering speeds east, and given weak instability and limited moisture, they should be short-lived. Therefore, NO flooding is expected today.

Primetime: 2PM to 11PM

Issue Date: Saturday, August 27th, 2022
Issue Time: 10:25 AM MDT

— Flooding is NOT expected today
— Fire-Burn Forecast Summary: 3 burn areas under LOW threat, click HERE for more info 

This morning, midlevel dynamics associated with the upper trough continue to move out of eastern Colorado, with drier air and subsidence pulling in behind it. Meanwhile, a weak disturbance in the flow is forecast to move into western Colorado with some subtle midlevel dynamics this afternoon, as noted by the furthest west “X” in the water vapor image below. Moisture throughout the column and boundary layer has dropped notably since yesterday for central and western Colorado, with Grand Junction measuring a PW value of 0.78 inches this morning, and Platteville measure a PW value of 0.75 inches. At the surface, dewpoints in the mid-40s°F are common over western Colorado except for some low-50s°F noted over the far southwest portions of the state near the New Mexico border. Dewpoint depressions are small for much of western Colorado and resulted in valley fog this morning across some lower elevations that is beginning to erode.

As the weak midlevel impulse enters western Colorado this afternoon, it will combine with the diurnal upslope circulation to trigger isolated storms over some of the higher elevations west of the Continental Divide. With surface moisture forecast to mix out significantly today, these storms should produce primarily gusty winds north and west of the Continental Divide, with the heavier rainfall chances focused over the southwest portions of the state where more residual surface moisture should remain. Additionally, instability values between 800-1200 J/kg of CAPE are forecast for these areas. Given steering speeds forecast in the 5 to 10mph range, these storms could potentially anchor to the high terrain and produce relatively brief, but locally heavy rainfall within a few hours window before instability drops and drying increases. However, rain rates are expected to remain just below flood thresholds so NO flooding is expected today.

Over far eastern Colorado, dew points in the mid and upper 50s°F and even low 60s°F were noted with PW above 1 inch. Though some continued drying is expected statewide, some areas in the far southeastern plains may be able to hold onto some surface moisture. An isolated storm or two may drift across this area and produce brief, locally moderate to heavy rainfall due to higher instability values forecast to reach between 1200-1800 J/kg of CAPE. However, forcing for storms in this area should be weak and thus preclude a greater rainfall threat. NO flooding is 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: 

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

Early morning valley fog across some lower elevations is eroding, leading to mainly clear skies for the western half of the state. This afternoon, isolated to widely scattered storms are expected to develop over primarily the higher terrain west of the Continental Divide. These storms will be capable of producing 30-to-45-minute rain rates of up to 0.8 inches, along with lightning and gusty winds for mainly the Southwest Slope, western San Juan Mountains, and the Grand Valley. Further north, isolated storms are also possible over the Northwest Slope and Northern Mountains, but given the forecast dry boundary layer, 30-to-45-minute rain rates up to 0.5 inches are anticipated. Aside from isolated light runoff over the steeper terrain and perhaps some minor road and field ponding at lower elevations under the isolated stronger storm cores, NO flooding is expected today.

Primetime: 1PM to 9PM

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

Clear skies and temperatures slightly cooler than yesterday are expected for eastern Colorado today. With some surface moisture forecast to remain in place over the far Southeast Plains, a few isolated storms may be possible over the southeastern border counties. Forcing is lacking, but given the forecast moderate instability and a fairly deep layer of southerly flow, a storm or two may be able to stall out and produce 30-to-45-minute rain rates up to 0.8 inches, along with gusty winds and perhaps some small hail. A few stray weak showers may also be possible over the Front Range and Southeast Mountains, as well as over the far Northeast Plains, but moisture and instability are much more lacking in these areas. NO flooding is expected today.

Primetime: 2PM to 8PM

Issue Date: Friday, August 26th, 2022
Issue Time: 10:05AM MDT

— A LOW flood threat has been issued for the Southwest Slope, Raton Ridge, Southeast Plains, and portions of the Palmer Ridge, Southeast Mountains and Northeast Plains
— Fire-Burn Forecast Summary: 1 burn area under MODERATE threat, 8 burn areas under LOW threat; click HERE for more info

The water vapor imagery below shows the breakdown of the ridging pattern as several shortwaves continue to move through the flow. A weaker shortwave (smaller orange “X”), which helped produce the more numerous showers and storms yesterday, is forecast to move eastward into the plains today. Currently, it is helping to produce lots of cloud cover across the state and showers over the mountains. In response to the shortwave, a surface trough is forecast to develop over the adjacent plains, which should pull in a decent amount of moisture over the eastern plains with southerly surface flow. As the storms spillover into the adjacent plains with the eastward movement of the mid-level dynamics, upscale growth of the storms is expected with enhanced lift and higher instability over the area. Thus, an uptick in rainfall activity is anticipated today. It should be a bit quieter of over the northern portion of the state (north of I-70) with only isolated mountain storms forecast later this afternoon and evening thanks to increased subsidence behind the departing trough and slight drying of the atmosphere.

PW at Grand Junction was measured at 1.07 inches this morning and 0.83 inches at Platteville with values estimated around 1 inch across the southern border and the far eastern plains. So, it’s clear that the monsoon moisture is still overhead, which will be recycled today and potentially produce some higher rainfall rates. One limiting factor to the heavy rainfall threat, especially over the mountains, is the ongoing showers and cloud cover. It’s likely that this will limit the amount of instability that can build causing storms to be more stratiform in nature, which will reduce the flood threat. Visible satellite shows some drier air moving across portions of the southwest border, which will likely allow for moderate instability to build by early afternoon and increase the threat for convective storms over the high terrain in this area. A LOW flood threat has been issued. There has also been a LOW flood threat issued for portions of the eastern plains where convective storms will be more likely to develop this afternoon and evening. With the low-level jet kicking in this evening, it’s likely that rainfall will continue overnight for the plains.

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

Over the mountains more scattered storm activity is forecast today with max 30-minute rain rates up to 0.4/0.6 inches (north/south) and isolated storm totals up to 0.9 inches (south) possible. Numerous to widespread showers are forecast by afternoon and into the evening as storms move off the higher terrain into the adjacent plains. Isolated max 1-hour rain rates up to 2.25 inches will be possible, so a LOW flood threat has been issued. In addition to heavy rainfall, the more intense thunderstorms will likely produce strong outflow winds and perhaps isolated hail. Rainfall will likely continue overnight, but the flood threat should end just after sundown.

Primetime: 12PM to 1AM 

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

Widespread, stratiform rainfall is expected over the central/southern mountain zones with totals up to 1.6 inches possible. Isolated convection could develop over the southwest high terrain near the western border by this afternoon. Max 30-minute/1-hour rain rates up to 1/1.3 inches will be possible if stronger storms develop where there are breaks in cloud cover, so a LOW flood threat has been issued.

Primetime: 12PM to 9PM