Issue Date: Sunday, September 18th, 2022
Issue Time: 8:55AM MDT

— Flooding is NOT expected today

The visible satellite image below shows a mostly clear start to the day with some clouds and fog across the northeast corner of the state. The disturbance and moisture that is causing this will continue weaken throughout the morning, and conditions should become sunny by lunchtime. Dry WSW flow continues to scour out the remaining moisture, and as a result, PW at Grand Junction and Platteville have plummeted to 0.38 inches and 0.41 inches, respectively. With High pressure continuing to build over Texas and Oklahoma today, rising heights across should cause an increase in afternoon high temperatures when compared to yesterday. Between the lack of moisture and increasing subsidence, the state is expected remain dry this afternoon and evening. Best chance for a little bit of rainfall will be over the San Juan Mountains overnight where increasing southwesterly flow may bring a little moisture and mid-level lift to the area. However, only very light rainfall is forecast, so flooding is NOT expected.

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

It will likely get a bit breezy this afternoon with southeast winds forecast in the 15 to 22 mph range. Afternoon temperatures are expected to increase and should reach between 3-6°F above normal. With dry air overhead, rainfall is not anticipated this afternoon, but light rainfall may be possible overnight for the San Juan Mountains. Due to totals remaining under 0.1 inches, flooding is NOT expected, and the increase in cloud cover will likely keep overnight temperature a little warmer.

Primetime: 9PM to 6AM

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

It’s going to be hotter today with afternoon temperatures reaching into the 90s °F across the lower elevations. Some fair weather cumulus are possible this afternoon, but rainfall is NOT expected. Westerly winds may get a bit breezy over the higher elevations of the mountain zones this afternoon.

 

Issue Date: Saturday, September 17^th, 2022
Issue Time: 8:55AM MDT

— Flooding is NOT expected today

Little change in the overall weather pattern has occurred over the past 24 hours. As shown in the visible satellite image, below, WSW flow aloft continues overhead. However, the flow has increased in strength as a developing jet streak forms over the Great Basin. Moisture has stayed essentially steady since yesterday morning, with Grand Junction PW measuring 0.76 inches and Platteville coming in at 0.64 inches. However, some drier air is continuing to advect in from the south. Dynamics-wise, a weak, poorly organized mid-level disturbance was draped across Utah, stretching into southwest Colorado. As this disturbance moves across the northwest quadrant of the state, sufficient moisture will allow for widely scattered thunderstorms mainly along the Wyoming border. Additionally, a few convergence boundaries should result in the flare up of isolated to widely scattered storms over the Northeast Plains. In both areas, however, with the strong steering flow exceeding 20mph and limited instability, only 30-45 minutes of moderate intensity rainfall is expected. Thus, there is NO flood threat 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, Central Mountains, Front Range, Urban Corridor & Northeast Plains:

Partly cloudy with isolated to widely scattered showers and storms expected, beginning around noon. Max 30-min rain rates up to 0.3 inches (west of I-25) and up to 0.6 inches (east of I-25). Gusty winds up to 40 mph will also accompany the storms. Flooding is NOT expected today.

Primetime: Noon through 7PM

San Luis Valley, Grand Valley, San Juan Mountains, Southwest Slope, Southeast Mountains, Raton Ridge, Palmer Ridge & Southeast Plains:

Mostly sunny and seasonably warm with an isolated shower or storms possible over northern portions of the area. Max 30-min rain rates up to 0.2 inches. Gusty winds are expected this afternoon. Flooding is NOT expected today.

Primetime: Noon through 6PM

Issue Date: Friday, September 16th, 2022
Issue Time: 9:05AM MDT

— Flooding is NOT expected today
— Fire-Burn Forecast Summary: 5 burn areas under LOW threat; click HERE for more info

The moisture plume and mid-level lift that was responsible for the rainfall over the last couple of days has moved east of the state, as shown by orange “X” in the water vapor imagery below. A drier WSW flow filled in behind it, which is reflected in this morning’s PW values. PW at Platteville has dropped to 0.65 inches, and PW at Grand Junction was measured at 0.75 inches. The slightly higher value at Grand Junction is due to a little moisture from a weak incoming shortwave, which is marked by the dashed orange line below. This area of lift is already producing some weak thunderstorms over the northwest corner of the state. As this area of mid-level lift moves ENE throughout the day, it is expected to spark additional storms over the northern tier of the state. Scattered storms are anticipated to develop over the northwest and northern high terrain by midday with more isolated storm coverage forecast over the adjacent plains (north of I-70). Fast steering flows associated with a jet streak should keep storms moving pretty darn quick, so only brief rainfall is anticipated from the storm cores. Additionally, drying in the mid-levels should help reduce rainfall rates. Therefore, 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, Grand Valley, Northern Mountains, Central Mountains, Front Range, Urban Corridor & Northeast Plains:

Additional storms are forecast to develop over the northern high terrain by midday with more isolated storms over the adjacent plains later this afternoon and evening. Max 30-minute rain rates up to 0.75 inches (west/plains) and 0.5 inches (Urban Corridor) will be possible. With fast storm motion and only moderate rainfall rates, flooding is NOT expected today. In addition to brief rainfall, storms may produce some stronger outflow winds (~45 mph) and lightning. Additional light showers are possible over the northwest corner overnight.

Primetime: Ongoing to 9PM

San Luis Valley, San Juan Mountains, Southwest Slope, Southeast Mountains, Raton Ridge, Palmer Ridge & Southeast Plains:

Very isolated storms may be possible over the high terrain this afternoon, but the drying trend will help produce more virga than wetting rainfall. It will likely get a little breezy over the mountains by this afternoon with gusts up to 30 mph possible across the higher peaks. High temperatures should be slightly cooler than average over western CO with temperatures reaching a few degrees above average over the plains and SLV.

Issue Date: Thursday, September 15^th, 2022
Issue Time: 10:25AM MDT

— A LOW flood threat has been posted for parts of the Palmer Ridge and Northeast Plains
— Fire-Burn Forecast Summary: 3 burn areas under LOW threat; click HERE for more info

One does not have to live in Colorado for a long time to know that morning clouds during the warm season are unusual. As seen in the visible satellite image, below, an expansive cloud deck resides over the western and central parts of the state. Ongoing showers and weak storm activity is noted over the Northern Mountains, Central Mountains and Northwest Slope. The supporting feature is a mid-level disturbance, of modest intensity, draped from northwest Colorado through the New Mexico border. This feature is well juxtaposed with a moisture maximum: this morning’s PW at Grand Junction continued to run high at 0.91 inches, while Platteville came in at 0.80 inches.

As the disturbance moves across the state, PW is expected to stay elevated over central and eastern Colorado, while falling slightly over far western areas. This will support scattered to widespread showers and storms today, mainly over the northeastern quadrant of the state. Most activity over the higher terrain will be benign, with only brief moderate to (very briefly) heavy rainfall expected. Instability will be a key uncertainty as the expansive cloud deck will limit heating in its vicinity. However, over parts of the Front Range, Palmer Ridge and Northeast Plains, instability up to 1,200 J/kg CAPE is expected to develop this afternoon. Additionally, with low-level flow backing to have a notable southerly component by early afternoon, a Denver Cyclonic Vorticity Zone is expected to develop. This will promote enhanced convergence over the climatologically favored Palmer Ridge area. In this region, 30-60 minutes of heavy rainfall will be possible during a 2-3 hour window this afternoon. A LOW flood threat has been posted for isolated flash flooding in this region. Storms are expected to weaken into showers by early evening as instability wanes. Nonetheless, very welcome rainfall is expected for parts of the Northeast 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:

Northeast Plains, Urban Corridor & Palmer Ridge:

Increasing clouds with scattered to widespread showers and storms developing by early afternoon. Max 30-min/60-min rain rates up to 1.2/1.6 inches possible especially over parts of the northern Palmer Ridge. A LOW flood threat has been posted for this area.

Elsewhere, brief moderate to heavy rainfall is possible especially during the afternoon, with max 30-min accumulation up to 0.6 inches (west) and 1.0 inches (east). However, flooding is NOT expected.

Primetime: 1PM to 9PM

Northwest Slope, Northern Mountains, Central Mountains, Front Range & Grand Valley:

Mostly cloudy with scattered showers and embedded storms expected through mid-afternoon, then some clearing is possible. Cool conditions with temperature 5-10F below normal today. Max 30-min rain rates up to 0.5 inches possible. Some ponding of runoff may occur, but flooding is NOT expected today.

Primetime: 10AM through 5PM

San Juan Mountains, Southwest Slope, Southeast Plains, Southeast Mountains, Raton Ridge & San Luis Valley:

Mostly sunny early, then partly cloudy with isolated to widely scattered showers and weak storms possible. Max 30-hour rain rates up to 0.7 inches (far eastern areas towards KS border) and 0.4 inches (west of I-25). Flooding is NOT expected today.

Primetime (west): 10AM through 4PM
Primetime (east): 1PM through 9PM