Issue Date: Saturday, July 16^th, 2022
Issue Time: 9:55AM MDT

— A MODERATE flood threat has been posted for parts of the Palmer Ridge, Central Mountains, San Juans and Southeast Mountains
— A LOW flood threat has been posted for parts of the Front Range, Southeast Plains, Southwest Slope, Raton Ridge and San Luis Valley
— Fire-Burn Forecast Summary: 4 burn areas under MODERATE threat; 5 burn areas under LOW threat; click HERE for more info

As shown in the visible satellite image, below, a relatively persistent monsoonal upper-level flow pattern continues over Colorado and the Four Corners today. However, it is the moisture content that is most noteworthy, and will once again drive an elevated flood threat today. With this morning’s Grand Junction PW coming in at 1.22 inches (~95^th percentile), very efficient rainfall rates are expected once again today. Further east, Denver’s PW was once again unfortunately missing due to the nationwide helium shortage, but soundings at North Platte, NE (PW 1.42 inches; 90^th percentile) and Dodge City, KS (PW 1.26 inches; 75^th percentile) all suggest well above normal moisture content across all of Colorado. Surface moisture also continues to be very impressive with morning dewpoint temperatures in the 50s F over central and western Colorado, while readings up to 70F were noted over the Northeast Plains agricultural belt this morning!

In terms of forcing today, we have clearing skies this morning as the departing cloud deck and associated disturbance from yesterday’s storms continues to move out of the state. Subsidence is notable on the western side of this feature (see “X” in visible image below) and will affect northern Colorado today, limiting storm activity to just the preferred higher elevation areas around the Continental Divide. Further south, with plenty of sunshine, weak steering flow and abundant moisture: we all know the drill. Instability up to 900 J/kg CAPE will fuel scattered to numerous will spark by early afternoon over mainly the southern Front Range, Palmer Divide, Central Mountains and San Juan Mountains. With a large cloud warm layer expected (i.e. tropical-style raindrop generation), very heavy rainfall will be possible over the 30-60 minute duration today, warranting a general LOW flood threat. Over parts of the Central Mountains, Palmer Divide and San Juan Mountains, higher coverage of storms warrants a MODERATE flood threat as multiple storm passages could occur over the same location.

Further east, storms will form another complex today as they head east-southeast off the Palmer Divide later this afternoon. With marginal instability, heavy rainfall should be limited to the 60-minute duration but a LOW flood threat is warranted all the way to the KS border as there is a sufficient chance that isolated storm cores will produce rain rates exceeding Flash Flood Guidance for the area.

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 Plains, Front Range, Northern Mountains, Central Mountains, San Juan Mountains, Southwest Slope, San Luis Valley, Palmer Ridge, Southeast Mountains & Raton Ridge:

Becoming partly to mostly cloudy with scattered to numerous showers and storms developing by early afternoon over the higher terrain. Max 30-min rain rate up to 1.8 inches (east) and 1.5 inches (west) with max 60-min rain rates up to 2.5 inches (east) and 2.2 inches (west). Highest storm coverage will occur over the Palmer Ridge, northeast San Juan Mountains and Southeast Mountains, where a MODERATE flood threat is warranted. Flash flooding, debris slides and mud flows will be possible especially over steeper terrain. Small creeks and streams will also be prone to riverine flooding. Elsewhere a LOW flood threat is in place for mainly isolated flash flooding, with debris slides and mud flows also possible.

Primetime: 12PM to 9PM (west), 2PM to midnight (east)

Northeast Plains & Urban Corridor:

Partly cloudy then isolated to widely scattered showers and storms possible this afternoon. Max 30-min rain rate up to 0.7 inches possible. Outside of nuisance field and road ponding of rainwater, flooding is NOT expected today.

Primetime: 12PM to 8PM

Grand Valley & Northwest Slope:

Mostly sunny early then isolated showers and storms possible this afternoon, especially over the foothills. Max 30-min rate up to 0.5 inches possible but flooding is NOT expected today.

Primetime: 11AM to 7PM

Issue Date: Friday, July 15th, 2022
Issue Time: 10:25AM MDT

— A MODERATE flood threat has been issued for the Northern Mountains and portions of the Northwest Slope and Front Range
— A LOW flood threat has been issued for the Central Mountains, San Juan Mountains, Urban Corridor and Northeast Plains
— Fire-Burn Forecast Summary: 3 burn areas under HIGH threat, 4 burn areas under MODERATE threat, 3 burn areas under LOW threat; click HERE for more info

A very active rainfall day is on tap for Colorado with an abundance of monsoon moisture forecast across the state (blue and white in the water vapor imagery below). PW at Grand Junction was measured at 1.2 inches, which is right around the maximum moving average for peak monsoon season. Currently, some mid-level lift is combining with the copious amount of moisture to produce some scattered showers and weak storms over western Colorado. Additional mid-level lift (orange “X’s”) is forecast to move clockwise around the High over the next couple of days, which paired with daytime heating will help to spark scattered to numerous thunderstorms over western Colorado, the mountains and Northeast Plains today.

As mentioned above, surface moisture is quite high over the state this morning with an increase in dew points between 3-5°F. There wasn’t a sounding at Denver, but dew points along the I-25 Corridor are in the 50°Fs with mid to upper 50°Fs over the eastern plains. While some of this moisture may mix out along the Urban Corridor, there should still be plenty for scattered rainfall as storms roll off the mountains and develop over the ridges. A LOW flood threat has been issued for areas near the elevated ridges with isolated, heavy rainfall possible.

Ongoing cloud cover this morning will likely help to limit the instability that can build over the Central Mountains and western high terrains, but pockets of moderate instability could still develop and numerous rounds of rainfall are anticipated. A LOW flood threat has been issued for this reason. Better chance for heavy rainfall today is over the Northern Mountains and Front Range where more instability can form with clearer skies. There should be just enough shear that a couple stronger thunderstorms are possible with the main threat being outflow winds and hail. A MODERATE flood threat has been issued. The flood threat should end by this evening over the mountains, although some overnight precipitation is likely across the Northern Mountains.

One last area of concern for flooding is the Northeast Plains tonight where a couple of stronger thunderstorms are possible as storms move into the area with WSW steering flow. It looks like the low-level jet could kick in, which would help fuel these storms and possibly grow them into a MCS if they can reach the area around sunset. A LOW flood threat has been issued with the storms likely winding down after a couple hours with instability dropping off with the setting sun.

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

Numerous storms are forecast over the northern high terrains today with max 30-minute rain rates up to 1.25 inches and isolated 1 to 2-hour storm totals up 2 inches possible. This could cause mud flows and debris slides over steeper terrains as well as local road flooding. A MODERATE flood threat has been issued. In addition to heavy rainfall, stronger thunderstorms may produce moderate sized hail and wind gusts up to 60 mph. Further south, storms should be more scattered with isolated max 30-minute rain rates up to 1 inch and isolated storm totals up to 1.5 inches possible. A LOW flood threat has been issued. The flood threat should begin to wind down this evening although some overnight showers are possible over the Northern Mountains as additional mid-level energy moves over the area.

Primetime: 11AM to Ongoing

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

Best chance for heavy rainfall across the Urban Corridor will be near the elevated ridges. Isolated areas of max 30-mintue rain rates up to 1.1 inches will be possible. This could cause road and low-lying area flooding as well as field ponding. As storms move into the Northeast Plains, upscale growth is anticipated with hail and strong winds also likely to develop if this occurs. Max 1-hour rain rates up to 2 inches will be possible this evening, which could cause some road flooding and field ponding. A LOW flood threat has been issued. Thunderstorms over the plains should begin to dissipate by midnight.

It should remain relatively dry further south, but some widely scattered storms will be possible over the Southeast Mountains. Max 30-minute rain rates up to 0.5 inches will be possible, so flooding is NOT expected for this area.

Primetime: 1:30PM to 12PM

Issue Date: Thursday, July 14^th, 2022
Issue Time: 10:35AM MDT

— A LOW flood threat has been posted for parts of the Northern Mountains, Front Range and Central Mountains
— Fire-Burn Forecast Summary: 6 burn areas under MODERATE threat; 2 burn areas under LOW threat; click HERE for more info

A persistent monsoonal pattern continues across Colorado with an upper level ridge importing fresh moisture into the state from the southwest (see visible satellite image below). While the pattern seems similar from the big picture, on a local level, we continue to look closely at slight changes in moisture, cloud cover and steering flow to understand the flood threat. This morning, Grand Junction’s PW measured 1.02 inches, a slight increase from yesterday’s 0.96 inches and well above the seasonal normal of 0.75 – 0.8 inches. Dewpoint temperatures are also 3-8F higher over north-central and northwest Colorado suggesting the continued potential for heavy rainfall there. With instability up to 1,000 J/kg CAPE expected again this afternoon, a LOW flood threat is warranted for portions of the Central and Northern Mountains as well as the Front Range along the Continental Divide. Isolated maximum 30-60 minute rain rates are expected to exceed flash flood guidance over this steeper terrain. The main caveat today is the presence of cloud cover and ongoing light showers/sprinkles associated with a weak mid-level disturbance (see “X” in the satellite image below). This is expected to limit instability over the Northwest Slope and parts of the Northern Mountains, keeping moderate/heavy rain rates limited to the 15-30 minute duration that is unlikely to produce flooding.

Further east, the moisture profile is not as threatening with more dry air expected in the sub-cloud layer reducing the max rain rates and promoting the threat of gusty winds. To the south, wind shear will be so weak that storm updrafts are unlikely to sustain themselves long enough to produce a flood threat.

Finally, over southeastern and eastern Colorado, very hot temperatures are expected once again as little cloud cover is anticipated.

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:

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

Partly cloudy early then mostly cloudy with scattered to numerous showers and storms expected early this afternoon, lasting into the evening. Max 30-minute rain rates up to 1.0 inch and max 1-hour rain rates up to 1.4 inches warrant a LOW flood threat for mainly higher elevation locations (7,500ft+) of the northern and central parts of the region. Isolated flash flooding, mud flows and debris slides will all be possible, especially over the steeper terrain. Further south, max 30-minute rain rates up to 0.7 inches are possible, but flooding is NOT expected.

Primetime: 12PM through 8PM

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

Mostly sunny early then partly cloudy with isolated to widely scattered showers and thunderstorms expected this afternoon and evening. Highest coverage will be closer to the mountains and over the Northeast Plains, with little activity expected further southeast over the plains. Max 30-minute rain rates up to 0.7 inches are possible with max 1-hour rainfall up to 1.5 inches over parts of the Northeast Plains. Some nuisance ponding of rain water could occur, but flooding is NOT expected today. Gusty winds up to 40mph are also possible especially later in the afternoon over the Northeast Plains as storms grow into a larger complex.

Primetime: 2PM through 10PM

Issue Date: Wednesday, July 13^th, 2022
Issue Time: 10:45AM MDT

— A LOW flood threat has been posted for parts of the San Juan Mountains, Central Mountains, Northern Mountains and Northwest Slope
— Fire-Burn Forecast Summary: 4 burn areas under LOW threat; 3 burn areas under MODERATE threat; click HERE for more info

A typical mid-summer monsoonal pattern is seen in the atmosphere this morning over our state. However, as has been the theme since mid-June, one with plenty of moisture. A weak upper-level “monsoon ridge” continues to hang around the Four Corners, with ebbs and flows of moisture rotating clockwise around it. This morning, PW has increased notably in Grand Junction from 0.75 to 0.96 inches, though the boundary layer is only marginally moist (for lower elevation locations, that is). Overall, PW has increased into the 0.7 – 1.0 inch range across western Colorado, and was underestimated by 10-15% in this morning’s weather model initialization. Further east, some subtle drying was noted with PW falling by a few tenths of an inch into the 0.5 – 1.0 inch range across eastern Colorado. Closer to the surface, dewpoint temperatures in the 43-52F range were noted across western and southwestern Colorado. This is about 2-3F higher than yesterday morning (for a 1 degree increase in the dewpoint, CAPE instability can go up 100-200 J/kg depending on the moisture profile!). Moisture will remain steady or slightly increase over western parts of the state as a weak import of monsoon moisture is expected from the southwest.

With nearly clear skies statewide this morning, we expect a quick warm up this morning with scattered to locally numerous showers and storms developing over most of our western higher terrain. With the aforementioned above normal moisture, slow steering flow and CAPE instability of up to 900 J/kg, locally heavy rainfall will be possible mainly above about 7,500 feet. A LOW flood threat is warranted for 30-60 minute heavy rainfall capable of producing flash flooding, debris slides and mud flows over the steeper terrain. Rainfall from storms will likely have a hard time making it down into the lower elevations. Thus, the flood threat is distinctly limited to higher elevation locations today.

Further east, some drying of the atmosphere and a lack of dynamics will reduce precipitation chances. However, isolated storms are still expected to come off the higher terrain to produce short-term moderate/heavy rainfall along with gusty winds. With higher flash flood thresholds though, flooding is not anticipated over the lower elevations of eastern Colorado 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:

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

Mostly sunny early then partly to mostly cloudy and warmer with scattered to numerous showers and storms developing by early afternoon. Highest coverage will be over the higher terrain above 7,500 feet. Max 30-minute rainfall up to 0.9 inches is possible, with max 1-hour rainfall up to 1.2 inches. A LOW flood threat has been posted for most of the higher terrain for isolated flash flooding, debris slides and mud flows.

For lower elevations, gusty winds of 30-40 mph could also accompany the storms.

Primetime: 1PM to 9PM

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

Mostly sunny and warmer today with isolated to widely scattered storms possible mainly near the foothills. Max 30-minute rainfall up to 0.7 inches (west) and 1.0 inches (east) with max 1-hour rainfall up to 0.9 inches (west) and 1.4 inches east. Some nuisance ponding of rain is possible today but flooding is NOT expected. Gusty winds up to 40mph could accompany the strongest storms.

Primetime: 1PM to 10PM