Issue Date: Thursday, May 27th, 2021
Issue Time: 8:25AM MDT

— Flooding is NOT expected today

The Low that brought a couple severe thunderstorms to the Northeast Plains yesterday also dropped a weak cold front across eastern Colorado. There was some surface moisture return behind the front, which is helping produce fog and cloud cover over the eastern central plains this morning. As the Low/trough continues to move eastward throughout the day, subsidence and northwesterly flow from a transient ridge will move over the state. This northwesterly flow will be dry and help to mix out this morning’s moisture return over eastern Colorado. With PW expected to drop from 0.57 inches at Denver and 0.43 inches at Grand Junction, storms that develop this afternoon will be sparse and high-based making more of a wind threat with only light rainfall forecast. This is especially true across the San Juan and southern Southeast Mountains where some mid-level energy working through the flow will help spark some high-based storms. Best chance for measurable rainfall will be over the southern high terrains and along the Palmer and Raton Ridge this evening, but only light accumulation is forecast. Therefore, flooding is not forecast 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:

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

Temperatures will remain above average across all regions today and the valley locations may reach up to 10F above average today (central, north). Surface winds will pick up over the higher terrains again this afternoon but are not forecast to be widespread or as high as yesterday. This should help limit fire danger. Weak mid-level energy will move across the southern border this afternoon, which will likely help to spark some high-based showers over the San Juan Mountains. More wind than rainfall is forecast, but areas near and along the Continental Divide could see isolated totals up to 0.15 inches. Flooding is not forecast.

Primetime: 1PM to 8PM

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

Temperatures should be around normal this afternoon thanks to the weak cold front that moved through yesterday. More cloud cover and wind, rather than rainfall, is expected with storms that develop today due to moisture being confined to the mid-layers of the atmosphere. Best chance for accumulation and storms will be across the elevated Ridges and Wet Mountains. Isolated totals up to 0.20 inches will be possible.

Primetime: 3PM to 9PM

 

Issue Date: Wednesday, May 26th, 2021
Issue Time: 9:30AM MDT

— Flooding is NOT expected today

As shown in the visible satellite image, below, a potent trough is centered over the Great Basin and will race eastward across Colorado through the day today. An accompanying surface low pressure is located over far northwest Colorado and will intensify while moving eastward through the day as well. This will also drag a cool front across the state later today, mostly noticeable with a wind shift as opposed to precipitation. Although dynamics are impressive, moisture is lacking. This morning’s PW at Grand Junction was a measly 0.32 inches, and even most of that was in the mid and upper levels of the atmosphere. Denver’s PW was 0.54 inches, close to normal for this time of year. However, much drier air was located across southwest Colorado and will overtake most of the state once again throughout the day.

The only area of concern today is the Northeast Plains, where a moist, low-level flow will contribute to push PW near 1.0 inch by this evening. In fact, this is already noticeable this morning with elevated convection causing large hail just across the KS border. With the aforementioned cool front boundary in place this afternoon, severe thunderstorms are likely along the NE and KS borders. Large hail, damaging winds and tornadoes will be possible with the strongest cells. Short-term heavy downpours will be likely as well, but prolonged heavy rainfall is unlikely given the relatively fast steering flow along with winds turning more westerly with time. Thus, flooding is NOT expected today.

Switching topics, it appears that the Purgatoire River has crested overnight near Las Animas. A Flood warning is still in effect, but without precipitation, the river will quickly fall below flood stage.

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.
A NWS Flood Warning is ongoing for the Purgatoire River near Las Animas through Wednesday afternoon. However, the river has crested and flow should quickly recede later today.

Zone-Specific Forecasts:

Northeast Plains, Southeast Plains

Isolated to scattered showers and thunderstorms this afternoon and into early evening. The biggest threat will be large hail, damaging winds and tornadoes as opposed to heavy rainfall. Max 1-hour rain up to 1.3 inches will be possible. Isolated nuisance street and field flooding will be possible.

Primetime: 12PM through 9PM

Front Range, Urban Corridor, Southeast Mountains, Raton Ridge, Palmer Ridge:

Variable cloudiness with an isolated shower or weak storm possible for northern areas. Max 1-hour rainfall up to 0.4 inches. Flooding is NOT expected today.

Primetime: 12PM through 6PM

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

Partly cloudy with gusty winds developing this afternoon. Isolated to scattered rain and high-elevation snow showers are possible this evening and overnight mainly in the Central and Northern Mountains. Flooding is NOT expected today.

Issue Date: Tuesday, May 25th, 2021
Issue Time: 8:50AM MDT

— Flooding is NOT expected today

Lingering cloud cover and a little fog remains over the far eastern plains from the storms that fired last night. The surface Low from yesterday is currently located over the southeast corner of the state and is forecast to move eastward throughout the day. As it exits, a few light showers may be possible on its north side over the plains. The exiting Low combined with dry, westerly flow aloft means that remaining moisture over the eastern portion of the state is forecast to decrease throughout the day. With PW values measured at 0.35 and 0.31 at Denver and Grand Junction, respectively, measurable rainfall is not forecast today. A couple sprinkles may be possible over the southern Front Range/Palmer Ridge this evening, but with high-cloud bases, the more likely scenario is virga. Flooding is not forecast.

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.

A NWS Flood Warning has been issued for the Purgatoire River near Las Animas through Wednesday afternoon. The river is forecast to crest at 9 feet, which is in the Minor flood stage.

Zone-Specific Forecasts:

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

High temperatures across the lower elevations should increase into the mid-70Fs with low 80Fs over the Southeast Plains. Mountain locations should reach the mid-60Fs. Scattered cloud cover will likely develop over the mountains and Palmer Ridge this afternoon. Best chance for a sprinkle or two will be across the southern Front Range and Palmer Ridge, but the more likely scenario is virga. Flooding is not forecast. Cloud cover begins to fill in overnight as the next trough approaches, so expect overcast conditions in the morning.

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

Warming up today with mid-70Fs to 80Fs for the valley locations. Over the mountain valleys upper 60Fs to low 70Fs are forecast. Rainfall is not forecast today, and blue skies should be plentiful. By this evening mid and upper level cloud cover should move over the western portion of the state as the next trough approaches, so except less sunshine tomorrow morning.

Issue Date: Monday, May 24th, 2021
Issue Time: 9:35AM MDT

— Flooding is NOT expected today

The dry air that was over western Colorado yesterday has been entrained into the eastern portion of the state with the continued southwesterly flow aloft. This can be seen by the shades of yellow over the state in the water vapor imagery below. PW at Grand Junction was measured at 0.27 inches, and over Denver PW has dropped to 0.23 inches. The remaining energy from the trough that brought storms to Colorado the last couple of days will move through the state today (orange line in Utah). With a dry and stable airmass in place, only a few fair weather cumulus are expected this afternoon over the high terrains. So, the forecast is plenty of sunshine statewide with temperatures over the eastern portion of the state similar to yesterday and a slight cool down over the western half of Colorado.

Late tonight, there is a chance for some thunderstorms over the central, eastern border counties. It is likely that moist outflow boundaries from storms over KS will push back west across the border with low-level moisture also being reinforced on the north side of a surface low. This moisture could mix with a low-level jet (left exit) and mid-level energy to produce an isolated line of thunderstorms. Although storms would be isolated in nature, nearly stationary movement could produce brief local, heavy rainfall. At this time, it does not appear that flood threat thresholds will be met, but if necessary, a PM update will be issued. Flooding is not forecast.

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, Northeast Plains & Palmer Ridge:

Clear conditions are forecast today with highs in the 80Fs (south) and 70Fs (north/west). Overnight, a line of thunderstorms may develop along the eastern border where high moisture and favorable dynamics will be in place. Although brief, heavy local rainfall will be possible with the nearly stationary storms, instability looks to be a limiting factor for widespread heavy rainfall. Isolated rainfall totals up to 1.25 inches will be possible. If the flood threat increases throughout the day, a PM update will be issued.

A Flood Watch has been issued for the Purgatoire River near Las Animas from Tuesday evening to Wednesday afternoon. Action stage was reached at the Arkansas River at La Junta gauge on Sunday (high flows had retreated here as of 9AM).

Primetime: 11PM to 5AM 

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

Plenty of sunshine with a few fair weather cumulus forecast over the mountains this afternoon. Although there is plenty of fog this morning, this should burn off rather quickly with the mixing out of the shallow surface moisture. Stable conditions and the dry air mass will keep rainfall out of the forecast today. Highs are forecast to be in the 80Fs (south), 70Fs for the Urban Corridor and 60Fs for the mountain valleys. Rainfall is not forecast.

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

Cold start to the morning, but clear skies and plenty of sunshine will help warm up the temperatures. Highs today are forecast in the 70Fs for the lower elevations and valleys. Over the mountain valleys, temperatures are forecast to be in the 60Fs. Rainfall is not forecast today.