Issue Date: Sunday, July 24th, 2022
Issue Time: 10:30AM MDT

— The flood threat persists into the overnight hours
— A HIGH flood threat has been issued for the Northeast Plains, Southeast Plains and Palmer Ridge
— A MODERATE flood threat has been issued for the Front Range, Southeast Mountains and Urban Corridor
— A LOW flood threat has been issued for the Northern Mountains, Central Mountains, San Juan Mountains and portions of the Grand Valley and Raton Ridge

— Fire-Burn Forecast Summary: 2 burn areas under HIGH IMPACT, 4 burn areas under HIGH threat; 3 burn areas under MODERATE; 2 burn areas under LOW threat; click HERE for more info

A very active rainfall day is on tap with a solid increase in monsoon moisture over the state as an incoming Low begins to the push the center of the High to the east. This will create WSW flow aloft, and this moisture combined with robust mid-level lift moving through the flow should help to produce numerous to widespread storms across the state. PW at Grand Junction has risen to 1.08 inches, and rainfall has already begun this morning over portions of the Northern Mountains, Grand Valley and Southwest Slope. Over eastern Colorado, a post-frontal upslope flow pattern will help to hold high dew points (mid-50°Fs and 60°Fs) in place. With steering flows decreasing across the state, very heavy rainfall will be possible under the stronger storm cores that develop. In addition to this threat, as storms move into the eastern plains, the threat for a couple severe thunderstorms increases with the main threat being damaging outflow winds.

With rainfall already beginning over northwest Colorado, a little more morning heating should expand the showers and weak storms fair quickly. It will be unlikely then that much instability can develop, so the heavy rainfall threat should be more limited over this area. Better instability is likely to build over the eastern and southern mountains, so as upslope flow and the mid-level lift combine, stronger thunderstorms and heavy rainfall are more likely. A LOW/MODERATE flood threat has been issued. As storms move into the adjacent plains, heavy rainfall is anticipated with slower steering flows, a couple rounds of rainfall and high dew points banked up against the high terrains. The one exception will be over the northern Urban Corridor where downsloping winds set up from the Denver cyclone. Upscale growth and a couple severe storms are anticipated as the storms move into deeper moisture over the far eastern plains. A MODERATE/HIGH threat has been issued that lasts into the overnight hours due to a few hours of widespread rainfall forecast. Flood threats today include mud flows/debris slides (steeper terrains), road flooding, heavy field and low-lying area ponding and flooding along local streams and creeks.

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:

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

Scattered to numerous storms are forecast to develop over the mountains by early afternoon with a couple stronger thunderstorms possible. These could produce small hail as well as strong outflow winds. Max 1-hour rain rates up to 1.75 inches (south) and 30-min rain rates up to 1.5 inches (north) are possible under the stronger storms that develop. This could cause mud flows and debris slides over the steeper terrains as well as road flooding and excessive runoff. A MODERATE/LOW flood threat has been issued. Storms should begin to end this evening (north), but rainfall will likely linger over the San Juan Mountains into tomorrow morning.

Primetime: 11:30AM to ongoing

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

Heavy rainfall is anticipated this afternoon and tonight with the scattered to numerous storms that develop. Max 1-hour rain rates up to 1.75 inches and storm totals up to 2.25 inches will be possible over the immediate adjacent plains. Over the far eastern plains, max 1-hour rain rates up to 2 inches are forecast under the stronger storm cores. Where storms linger for a few hours (border counties), isolated 3-hour totals around 4 inches will be possible. Flood threats today include the potential for heavy field ponding, road/low-lying area flooding and rises on local streams/creeks. In addition to heavy rainfall, damaging wind gusts will be possible over the far eastern plains where an MCS is likely to develop. Light rainfall may linger over the plains into tomorrow morning. A HIGH/MODERATE flood threat has been issued.

Primetime: 3PM to 3AM

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

Rainfall has already started over northwest Colorado. Max 1-hour rain rates up to 0.25 inches and storm totals up to 0.75 inches will be possible for the area. Over the central and southern high terrains isolated 30-minute rain rates up to 0.5 inches are forecast. A couple storms may make it into the interior of the San Luis Valley with the WSW steering flows, and isolated totals up to 0.4 inches will be possible. Light showers may linger overnight for the high terrains (central/south). Flooding is NOT expected today.

Primetime: Ongoing to Midnight

Issue Date: Saturday, July 23rd, 2022
Issue Time: 9:55AM MDT

— A LOW flood threat has been issued for the Front Range, Central Mountains, Northern Mountains and San Juan Mountains
— Fire-Burn Forecast Summary:  4 burn areas under MODERATE threat; 2 burn areas under LOW threat; click HERE for more info

Several disturbances north of the state can be seen in the water vapor imagery below. These will begin to break down the ridge, which has dominated our weather pattern over the past week+ bringing on and off storm activity to the state. As northwesterly flow begins to take over, cooler statewide temperatures are anticipated; however, the ridge will still be the dominating weather feature through this afternoon helping to produce one more day of hot temperatures. As far as rainfall, the High is pulling in a nice moisture plume over the state (blue shades) and a cool front dropping through eastern Colorado this afternoon should also help increase moisture over the plains. This should keep scattered to numerous showers in the forecast. Small disturbances (smaller orange “X”) embedded in the flow are already helping to produce some light showers and cloud cover over the state this morning, and these should also help produce an uptick in storm coverage this afternoon and evening.

PW at Grand Junction has increased to 0.9 inches with values slightly increasing towards the southern border. Over eastern Colorado, PW is estimated around a quarter of an inch with increasing values towards the eastern border. Surface moisture, outside of the far eastern plains, has increased from this time yesterday, and the cool front should help these eastern Colorado dew points somewhat recover by later in the day. One limiting factor to the heavy rainfall potential today will be faster westerly steering flows, mostly over the northern portion of the state. However, training and multiple rounds of storms along with a nice warm layer helping to increase efficiency should help boost local accumulations over some areas. A LOW flood threat has been issued for areas that this is most likely to occur within the high terrains. In addition to heavy rainfall, the scattered to numerous storms that develop today may also produce lightning, isolated small hail and strong outflow winds.

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:

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

Numerous to widespread storms are forecast to develop by early afternoon favoring areas near and along the Continental Divide for accumulation. While faster steering flows should somewhat limit the flood threat from any given storm, multiple rounds of storms and isolated areas of training may develop. Max 30-minute rain rates up to 1.25 inches and localized totals up to 1.75 inches will be possible. This could cause isolated mud flows and debris slides as well as road flooding and ponding in low-lying areas. In addition to heavy rainfall, isolated strong storms may produce brief outflow winds, lightning, and small hail. A LOW flood threat has been issued. Lingering showers and weak storms may persist overnight, but the flood threat should end a few hours after sundown as instability drops off.

Primetime: Noon to 11PM

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

Increasing westerly steering flows should push storms off the mountains and into the adjacent plains by early afternoon with scattered to numerous storms forecast. Additional storms may fire over the eastern plains along the cool front. With a drier boundary layer or limited surface moisture, storms may produce some gusty outflow winds despite some moisture return along the front. Max 30-minute rates up to 0.6 inches (west) and 1-hour rain rates up to 0.9 inches (east) will be possible. In addition to strong winds, isolated hail may be possible, but the severe storm potential remains low. Showers and weak storms may linger through the night with extra lift overhead. Flooding is NOT expected.

Primetime: 1PM to 4AM

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

Isolated to widely scattered storms should stick to the high terrains today with limited spillover into the valleys. Max 30-minute rain rates up to 0.4 inches and isolated storm totals just over 0.5 inches will be possible. Therefore, flooding is NOT expected. A Heat Advisory remains in effect for the Grand Valley, so be sure to drink plenty of water and limit outdoor activities.

Primetime: 1PM to 10PM

Issue Date: Friday, July 22nd, 2022
Issue Time: 9:50 AM MDT

— Flooding is NOT expected today

The drying trend continues statewide today, and temperatures are expected to soar into the triple digits for lower elevations. The high pressure has shifted just slightly back to the northeast, as shown in the water vapor image below, and is expected to continue a slight northeastward shift throughout the day. This should result in northwesterly steering flow turning more westerly as the day progresses. Overall column moisture continues to decrease from yesterday with Grand Junction measuring PW of 0.72 inches, which is near climatological average. Of note, high dewpoint depressions indicate a dry boundary layer, which should limit the rainfall threat overall today.

While surface moisture has recovered overnight some from yesterday’s drying, additional mixing out of moisture is expected for most of Colorado once again this afternoon. However, increasing upslope flow across southeastern Colorado should help hold some moisture in place across the higher elevations of southern Colorado this afternoon. Due to the robust surface heating expected today, instability is forecast to increase to 800-1000 J/kg of CAPE across portions of southern Colorado this afternoon. Widely scattered storms are expected to develop across the high terrains primarily west of the Continental Divide by early afternoon, although a few stray storms may drift over eastern foothills, Palmer Ridge, and eastern plains later this afternoon and evening. Brief heavy downpours, small hail and gusty winds will be possible; however, 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:

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

Skies are mostly clear this morning except for some stray high clouds, with pleasantly warm temperatures to start the day. Beginning early afternoon, widely scattered storms are expected to develop primarily over the higher elevations. The highest precipitation chances are expected over the San Juan Mountains where 30-minute rain rates up to 0.5 inches and 1 hour storm totals up to 0.75 inches are possible. Over the Central and Northern Mountains where moisture is forecast to be more limited, isolated 1 hour rain rates up to 0.25 inches are possible. Lightning and gusty winds are possible with any storms that develop. Hot temperatures are expected for the lower elevations and a Heat Advisory remains for portions of the Grand Valley through this evening. NO Flooding is expected today.

Primetime: Noon to 10PM

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

A few stray clouds are noted on visible satellite across these zones this morning, otherwise clear skies and warm temperatures are expected to quickly soar into the 90s and low triple digits this afternoon, particularly for the eastern plains. A Heat Advisory has been issued over the Northeast Plains this morning through this evening.

While ample surface heating is expected today, moisture is forecast to be quite limited until later this evening as upslope flow advects more moisture into the Southeast Plains region. A few isolated storms may develop later this afternoon over the eastern Southeast Plains and produce 30-minute rain rates of up to 0.25 inches. Further west, a few stray storms may develop over the high elevation ridges, but given the more limited moisture and instability forecast, precipitation with these storms is expected to be relatively light with virga showers and gusty winds likely. NO Flooding is expected today.

Primetime: 2PM to 9PM

Issue Date: Thursday, July 21st, 2022
Issue Time: 10:25 AM MDT

— Flooding is NOT expected today

Drier conditions are expected statewide today as compared to yesterday, with temperatures slightly cooler but still increasing across much of Colorado as the High builds northward. While the upper air pattern remains largely unchanged over the past several days, the High has moved slightly south and west over Arizona, as shown in the water vapor image below. With increasing northwesterly flow, there should be a decrease in overall moisture statewide as the day progresses. PW in Grand Junction was measured at 0.90 inches this morning, a slight decrease from yesterday but still above climatological normal. Near the surface, dew point temperatures range from the low to mid-40s°F for most of western Colorado, to low 50s° for central Colorado and up to the low 60s°F for eastern Colorado, which is slightly down from yesterday except over the eastern plains. This residual boundary layer moisture is forecast to mix out fairly substantially across most of northern Colorado by early this afternoon as dry air is advected into the region from Utah.

Widely scattered storms are expected to develop mainly over the higher terrains where enhanced convergence in the presence of instability of 500-800 J/kg of CAPE is forecast this afternoon. In addition, some isolated to widely scattered storms may make their way into the eastern plains, where deeper surface moisture and instability of 1200-1500 J/kg of CAPE is forecast. A couple of these storms may produce small hail, strong winds, and briefly heavy downpours. Outside of some minor field ponding, 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

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

This morning, temperatures are pleasant and skies are mostly clear aside from a few stray high clouds. By mid-afternoon, scattered storms are expected to develop initially over the higher terrains favoring areas south as well as over the elevated ridges. Isolated max 30-minute rain rates up to 0.75 inches will be possible. As storms move into the eastern plains with increasing northwesterly steering flow aloft and upslope flow at the surface, max 1-hour rain rates up to 1 inch will be possible along with strong outflow winds, small hail, and lightning. Outside of some minor ponding, flooding is NOT expected today.

Primetime: 2PM to 10PM

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

Some high clouds and a few isolated showers are occurring over the Northwest Slope this morning, otherwise skies are mostly clear. This afternoon, isolated to widely scattered storms are expected to develop primarily over the higher terrains mainly south. Due to the forecasted drier boundary layer moisture, these storms are expected to produce primarily gusty winds. A few briefly heavy showers may be possible particularly over the southern San Juan Mountains. Here, max 30 minute rain rates up to 0.6 inches and isolated storm totals just under 1 inch over 2 to 3 hours are possible. Flooding is NOT expected today.

Primetime: Noon to 9PM