Issue Date: Saturday, May 21st, 2022
Issue Time: 9AM MDT

— Flooding is NOT expected today

The late season winter storm will continue today, but the good news is that it should be winding down in both intensity and coverage after this morning. The base of the trough and accompanying jet are located over the Colorado and New Mexico border producing very cold air on its north side. Below is the 24-hour temperature change from yesterday (as of 5AM), and you can see even colder temperatures across the state behind that second front that came through.

Not much change in the general synoptic pattern throughout the day, which means the best dynamics and moisture will be over southeast Colorado through this afternoon. So, expect the scattered rain/snow mix to continue for this area. Precipitation begins to wind down further north and west with a bit of a drier air mass moving in and weaker dynamics; however, lingering snow over the central mountains is likely. Precipitation is expected to temporarily pause statewide this evening before another round of snow develops over the southern Front Range/northern Southeast Mountains overnight. Due most precipitation accumulating as snow today and only gradual rainfall forecast, there is NO flood threat issued. One other quick thing to mention, this was a widespread event with a large area receiving at least 0.75 inches of liquid precipitation equivalent. As this begins to melt later today and into tomorrow, it will likely cause a spike in local streams/creeks. At this time flooding is not expected, but we do anticipate a rise in streamflow over the next couple of days.

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, Southeast Mountains, Palmer Ridge, Raton Ridge & Southeast Plains:

Best coverage of precipitation today will be over these zones, which includes the southern portions of the Front Range and Palmer Ridge. Snow will begin to turn over to a cold rain across the Southeast Plains as the freezing line rises this morning. Max liquid equivalent totals up to 0.60 (adjacent eastern plains), 0.30 (east), 1.0 (ridges) and 1.5 (SE mtns) inches will be possible. Flooding is NOT anticipated today with a brief pause in precipitation forecast this evening. Overnight snow should generally be light over the southern Front Range/northern Southeast Mountains with up to 0.2 inches of liquid equivalent possible translating to a couple more inches of snow during this period. Light showers may linger over the far eastern Palmer Ridge into the morning hours.

Primetime: Ongoing to 4AM

Central Mountains, Northern Mountains, Northwest Slope, Northeast Plains, San Luis Valley, Urban Corridor, Southwest Slope, Grand Valley & San Juan Mountains:

Precipitation will continue to decrease over the Urban Corridor as the morning progresses. Only a couple more inches of snow are forecast. Isolated snow may be possible over the Central Mountains and San Juan Mountains as well as the elevated plateaus of the Grand Valley this morning/afternoon near the Continental Divide. Otherwise, it will remain dry for these zones with highs returning to the 60Fs across the lower elevations west. Highs in the mid-40Fs to low 50Fs are forecast for the lower elevations east, which will kick off the melting.

Issue Date: Friday, May 20th, 2022
Issue Time: 10:05AM MDT

— Flooding is NOT expected today

A robust trough has set up over the western US with a strong jet stream and cold temperatures accompanying it. Snow has already begun over the northern mountains and precipitation is spilling into the northern Urban Corridor this morning, which is aligned with the strong upper-level winds. The right entrance of a jet streak is anticipated to set up over the northern mountains and adjacent eastern plains today, which will help to provide enhanced lift to the area this afternoon into tonight. PW at Denver and Grand Junction was just over 0.50 inches, which means there’s plenty of moisture with the dynamic set up for widespread precipitation chances through tomorrow. For today, expect the current area of precipitation to expand in coverage over the Urban Corridor, western Northeast Plains and Palmer Ridge, and then tonight into the Southeast Mountains. A secondary push of cold air from the north should help drop the snow line by late this afternoon into the early evening hours over the Palmer Ridge and Urban Corridor. It will also push out the lingering warm air that is currently over the southern border later tonight.

Due to how warm it has been, there should be plenty of melting at the lower elevations, which will somewhat limit snow accumulation. Slick roads are also anticipated during this storm, especially as the temperatures begin to drop off overnight. Heavy, wet snow on the foliage could also mean downed branches and power outages, so be sure to remove the snow if you’re able to. Due to the gradual nature of the rain/snow mix today and transition to snow tonight, flooding is NOT expected. Expect the widespread precipitation over northern Colorado to become more widely scattered by late tomorrow morning. However, the rain/snow mix will likely linger over the Southeast Mountains and immediate adjacent plains through midnight on Saturday.

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, Northeast Plains, Palmer Ridge & Urban Corridor:

It’s going to be a big storm for the area with the best accumulation anticipated over the Front Range, southern Urban Corridor and Palmer Ridge. Storm total liquid equivalent up to 3 inches will be possible over the southern Front Range/Urban Corridor/Palmer Ridge intersect (Jefferson/Douglas Counties), and if there’s a quick crossover to snow with these higher amounts, snow totals could reach up to 2 feet. As for the Urban Corridor, there will likely be a strong gradient from north to south. Areas up north could see up to 1-3 inches, while on the south and west sides of Denver totals should generally be between 2-8 inches. Palmer Ridge is also expected to see higher precipitation with general snow totals in the 12 to 18 inches range. Again, how quickly the turnover from rain to snow occurs late this afternoon into the early evening hours and where the jet sits (should sag south) will help determine the final snow accumulations.

Generally, snow totals over the mountains should be between 12-20 inches over the Front Range, 8-12 inches over the Central Mountains and 3-6 inches over the Northern Mountains. Isolated areas of the Front Range, near the Continental Divide, could just receive over 30 inches of snow.

Northeast Plains and Northwest Slope could see up to 0.8 inches and 0.4 inches of liquid equivalent, respectively.

Primetime: Ongoing

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

Forecast the best precipitation accumulation for these zones to be over the Southeast Mountains, adjacent Southeast Plains and to a lesser extent, the Raton Ridge. Behind the frontal passage tonight, precipitation should set up along the southward sagging jet stream, so oriented from the southwest to northeast. Over the immediate adjacent plains, up to 0.25 inches of liquid equivalent is possible, but over the northern Southeast Mountains and Wet Mountains, up to 1.3 inches of liquid equivalent will be possible. The San Juan Mountains may see 1 to 2 inches of snow by Saturday morning, along with the elevated plateaus of the Grand Valley and Southwest Slope.

Ironically, it’s going to be hot, dry and windy day over the Southwest Slope and San Luis Valley, and a Red Flag Warning has been issued. The secondary push of cold air arrives this evening, which should drop temperatures into the 30Fs overnight.

Primetime: 1PM to Ongoing

Issue Date: Thursday, May 19^th, 2022
Issue Time: 9:45AM MDT

— Flooding is NOT expected today
— Widespread Red Flag Warnings in effect for most of Colorado

A common saying goes “If you do not like the weather [insert location here], just wait a few minutes”. On a day like today, this saying will be right on point for all of Colorado. As shown in the visible satellite image, below, a strong cold front is currently draped across the Northern Rockies. It will quickly move southward today and enter Colorado early this evening. Behind it, substantial moisture and vigorous dynamics will couple with our unique terrain to provide a powerful May snowstorm for most of the higher terrain and adjacent foothills. However, before we get there, with dry, downsloping winds increasing in strength today, afternoon high temperatures will hit their highest mark of the season for many locations east of the Continental Divide. Now add into the mix very low humidity values, and you guessed it: Red Flag Warnings are widespread today for all but northwest Colorado.

Precipitation will begin as rain below about 11,000 feet today but quickly change to snow. Snow levels will drop all the way to about 6,000 feet by morning. By tomorrow morning, up to 2.25 inches of liquid equivalent is expected over the Northern Mountains! Flooding is NOT expected today.

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 & Northwest Slope:

Increasing clouds and warm today with temperatures 5-12F above normal. Windy conditions will develop by afternoon ahead of the strong incoming cold front, and Red Flag Warnings are in effect for parts of the region. Rain and snow will quickly develop shortly after sunset. Max 1-hour rainfall up to 0.4 inches possible very early in the event before the transition to snow occurs. By tomorrow, up to 2.25 inches of liquid equivalent is expected over the Northern Mountains. However, flooding is NOT expected today.

A few streams in the Northern Mountains (especially the Elk River) are running high. Flows are expected to drop quickly tonight as snowmelt pauses for a few days.

Primetime: 6PM continuing into tomorrow morning

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

Partly cloudy with very warm temperatures today, running 10-20F above normal. Windy conditions will develop this afternoon and Red Flag Warnings are in effect. Late in the evening, rain and snow will develop over northern areas and spread south quickly during the overnight hours. Max 1-hour rainfall up to 0.4 inches is possible. Up to 1.4 inches of liquid equivalent is possible over the higher terrain by morning. However, flooding is NOT expected today.

Primetime: 9PM continuing into tomorrow morning

Issue Date: Wednesday, May 18th, 2022
Issue Time: 10AM MDT

— A LOW flood threat has been issued for the Southeast Plains

The best moisture and dynamics for storm development will move into southeast Colorado today, and a few severe storms will be possible over the far Southeast Plains late this afternoon and evening. Storms are forecast to develop with upslope flow and a little mid-level energy (orange “X”) over the southern Front Range, Palmer Ridge and Southeast Mountains by early afternoon. As they move off these elevated regions, an incoming trough over the Pacific Northwest will help steering flows gain a bit more of a northerly component. So, expect storms to move ESE at a moderate rate and initially only produce lighter rainfall, wind and a little lightning.

As far as moisture, after the passage of yesterday’s cold front, PW has bounced back to 0.59 and 0.61 inches at Denver and Grand Junction, respectively. At Dodge City, PW was measured just under an inch at 0.92 inches, so a nice gradient, as one would expect, as you move east. There also seems to a weak surface High circulation developing over the eastern border, that will help to produce dry, westerly winds on its north side, and moist, easterly and southeasterly winds on its south side. This should keep dew points in the low 50Fs over the far corner (green dashed line), and may help pull in slightly higher moisture, especially as the diurnal flow kicks in.

As the storms move into this deeper moisture, upscale growth is anticipated, and there is a greater threat for severe thunderstorms to develop. Strong winds will be possible as this occurs along with severe hail and local heavy rainfall. Although the flood threat is on the lower end today, minor road flooding and field ponding will be possible as the storms roll through the far Southeast Plains this evening. Therefore, a LOW flood threat has been issued.

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, Southeast Mountains, Palmer Ridge, Raton Ridge & Southeast Plains:

Storms will kick off over the southern Front Range, Palmer Ridge, Southeast Mountains and to a lesser extent the Raton Ridge by early afternoon. As storms move into the adjacent plains, they should encounter more moisture, which is when upscale growth is anticipated. Large dew point depressions back to the west mean more of a wind than rain threat, and this wind threat will grow as storms move to the southeast. Severe storms will be likely over the far corner with hail up 1 inch in diameter and gusts up to 65 mph possible, if the storms begin to bow. Max 1-hour rain rates up to 1.75 inches are forecast for the Southeast Plains, which could cause local flooding issues such a minor road flooding and field ponding, so a LOW flood threat has been issued. Over the mountains, isolated totals up to 0.15 inches and over the adjacent plains, max 1-hour rain rates up to 0.50 inches will be possible. So, flooding is not anticipated for these regions.

Primetime: 1PM to 8PM (west); 5PM to 10:30 PM (east)

Northeast Plains, San Luis Valley, Central Mountains, Northern Mountains, Northwest Slope, Southwest Slope, Grand Valley, San Juan Mountains & Urban Corridor:

Isolated storms may develop over the eastern San Juan Mountains and southern Central Mountains with isolated totals up to 0.40 inches (south) and 0.10 (north) possible. Elsewhere, it should remain dry today with 80Fs for the lower elevations and upper 60Fs to low 70Fs for the mountain valleys. Flooding is NOT expected.

Primetime: 1PM to 8PM