Issue Date: Sunday, May 29^th, 2022
Issue Time: 9:30AM MDT

— Flooding is NOT expected today
— Fire-Burn Forecast Summary: 9 burn scars under LOW flood threat; click HERE for more info
— Red Flag Warnings in effect for parts of southern Colorado

As expected, significant changes have occurred over most of our state since Saturday with the approach of a strong upper-level trough. The trough axis is currently centered over the Great Basin and will move into Colorado through the day. Rain and high-elevation snow showers as well as isolated thunderstorms are ongoing over the Northern Mountains and Northwest Slope as of this writing. With solar heating expected through the breaks in the clouds, instability will approach 1,200 J/kg across mainly central and western Colorado today, fueling widespread to numerous shower and storm activity.

There are two main limitations to the heavy rainfall threat today: moisture and wind speed (and shear). Starting first with moisture, this morning’s PW measured 0.55 and 0.54 inches at Grand Junction and Denver, respectively. While this is certainly respectable, there will be little additional moisture advection into the state today. In fact, there will be some eroding of moisture by drier air especially over southern Colorado (more on that below). Thus, any increase in moisture will have to come from the “top down”. That is, from rain itself. This is a slow process, and PW is expected to top out in the 0.6 to perhaps 0.7 inch range, which is generally on the low side to support heavy rainfall intensity. The other mitigating factor today is the steering flow and wind shear. West-northwest storm steering winds today will exceed 30 mph, which is very high. Moreover, wind shear, by any measure, will be very strong. With only moderate instability available, storms will have a hard time building vertically, which will favor lower storm height and more practically: lower rain intensity. So, to summarize, we certainly expect multiple rounds of moderate to perhaps briefly heavy rainfall (hence, the flood threat over burn areas, see headline link). But the limited duration of high rain intensity does not support flooding today. Thus, flooding is NOT expected.

Lastly, over southern Colorado, the aforementioned dry air and very windy conditions will continue to support Red Flag Warnings. Please use caution with outdoor fires.

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, Northwest Slope, Grand Valley, Front Range, Urban Corridor, Palmer Ridge, San Juan Mountains & Northeast Plains:

Partly to mostly cloudy and cooler with multiple rounds of shower and thunderstorm activity expected, especially this afternoon and evening. However, isolated to scattered storms are expected even into the overnight hours. The snow level will vary between 8,000 and 9,500 feet. Max 30-minute rainfall up to 0.8 inches (east) and 0.5 inches (west). Max 1-hour rainfall up to 1.0 inches (east) and 0.7 inches (west) with widespread total precipitation over 1.0 inch expected over the Northern Mountains by tomorrow morning. Flooding is NOT expected today.

A few storms could become severe, especially over the Northeast Plains. The main threat will be damaging winds.

Primetime: Ongoing through the overnight hours

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

Partly cloudy, cooler and very windy with isolated to widely scattered showers and thunderstorms possible this afternoon. Max 1-hour rainfall up to 0.4 inches. The snow level will range between 9,000 and 10,500 feet. Flooding is NOT expected today.

There are ongoing Red Flag Warnings in effect due to the wind and low humidity expected this afternoon and evening.

Primetime: 12PM through 7PM

Issue Date: Saturday, May 28^th, 2022
Issue Time: 8:30AM MDT

— Flooding is NOT expected today
— Red Flag Warnings in effect for southern Colorado

The first day of the Memorial Day weekend will bring about a major change to our weather pattern, swapping out heat for cooler, wetter (and whiter) weather beginning late this afternoon. As shown in the visible satellite image, below, the driver of the pattern change will be a strong Pacific-origin cold front that is currently draped to the north and west of Colorado. Supported by another strong jet streak, the mid and upper-level dynamics will cause lee-side cyclogenesis this afternoon, deepening a low pressure over southeast WY and eastern CO. While morning PW at Grand Junction and Denver was a paltry 0.40 inches, higher PW can be seen on the visible satellite image over the Great Basin. By late afternoon, PW will increase to near 0.7 inches over northwest Colorado causing a notable uptick in rain showers and isolated storms initially, then transitioning to rain and snow showers. Instability of up to 400 J/kg could briefly exist this afternoon over parts of the Northern Mountains, Northwest Slope and Central Mountains. However, with unidirectional steering flow exceeding 25 mph, any storms that do form will be short-lived, quick moving and more of a gusty wind threat, compared to rainfall. Thus, flooding is NOT expected today.

Speaking of wind, has anyone missed the gusty winds? Well, if you have, you are in luck because the strong jet stream and deep boundary layer will cause a 6-8 hour period of very gusty winds across almost the entire state this afternoon. With very dry air still anchored over mainly southern Colorado, the wind + low humidity + heat combination will cause a potent situation for spreading any wildfires. Thus, Red Flag Warnings are in effect across mainly the drier southern half of our state. Please be cautious with outdoor fires.

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, Northwest Slope & Grand Valley:

Partly cloudy early then mostly cloudy, cooler and very windy with scattered to widespread rain showers along with a few thunderstorms. Max 1-hour rainfall up to 0.4 inches an hour is possible. Flooding is NOT expected today, but up to 0.9 inches of liquid equivalent is expected to accumulate over the higher terrain of the Northern and Central Mountains by tomorrow morning.

Primetime: 2PM through the overnight hours

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

Partly cloudy, hot and windy today with high temperatures 5 – 18F above normal (hottest anomalies over the eastern plains). Isolated showers and weak storms are possible over the San Juan Mountains later this afternoon. An isolated weak storm cannot be ruled out over the Northeast Plains right along the NE/KS/CO tri-border area. Max 1-hour rainfall up to 0.3 inches. Thus, flooding is NOT expected today.

Red Flag Warnings are in effect for large parts of the area for this afternoon and evening, and even through Sunday for southeast Colorado.

Issue Date: Friday, May 27th, 2022
Issue Time: 9:10AM MDT

— Flooding is NOT expected today

Today will be our statewide peak in heat for the week. With the ridge axis still overhead, afternoon high temperatures are expected to be 4°F to 10°F warmer than yesterday. An incoming cold front is marked by an orange “X” in the water vapor imagery below with a nice dry slot defined behind it. This won’t quite reach western Colorado today, but increasing winds aloft and weak mid-level energy out in front of this feature are expected to move over the state by early this afternoon. This should result in a weakening of the ridge, a little lift and stronger westerly and southwesterly surface winds.

As far as moisture availability, PW has risen slightly to around 0.40 inches at both Grand Junction and Denver. Morning soundings showed most of the moisture was still located in the mid and upper levels. So with the dry sublayer remaining, only isolated, high-based storms are forecast today. With more of a wind than rainfall threat today, especially as storms are steered into the adjacent eastern plains, 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:

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

It’s going to get hot this afternoon with 80Fs and 90Fs forecast for the lower elevations. Mountain valleys should reach into the upper 60Fs and 70Fs. Isolated, weak storms are forecast to develop over the central and northern high terrains by midday through the afternoon. Isolated locations may see up to 0.20 inches of rainfall, but most storms are expected to produce brief windy conditions and totals under 0.05 inches. As storms are steered east into the adjacent plains, high bases should keep rainfall totals light (under 0.15 inches) with gusts up to 40 mph possible. Flooding is NOT forecast.

Primetime: Noon to 9PM

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

It’s going to be hot, dry and windy this afternoon for these zones. High temperatures are forecast to reach into the 80Fs for the lower elevations and will likely hit 90F for the Grand Valley. It is likely still too dry for any measurable rainfall north of I-70, but do expect an increase in afternoon cloud cover across all zones. Flooding is NOT forecast.

Flow has increased along the Green River due to releases at Flaming Gorge Reservoir (northwest CO). A Flood Advisory has been issued until next Thursday with minor flooding in low-lying areas possible.

Over southwest Colorado, including the San Luis and Grand Valley, southwesterly surface winds are forecast to reach the 20 to 30 mph range today due to mixing with the increase in winds aloft. Relative humidity will likely drop into the low teens to single digits for this area, so a Red Flag Warning has been issued. Be sure to tune into your local NWS office for more details.

Issue Date: Thursday, May 26th, 2022
Issue Time: 10:20AM MDT

— Flooding is NOT expected today

Aside from some light, high cloud cover over the mountains this morning, clear skies to start the day. As the upper ridge builds over the state today, expect dry, calm conditions over Colorado with above-average temperatures nearly statewide. Given that the axis of the ridge will progress eastward throughout the day, as shown by the yellow arrow in the water vapor image below, subsidence and calm surface winds are also forecast. Observed PW values were 0.31 and 0.37 inches in Grand Junction and Denver this morning, respectively, so not much change from yesterday. Lack of moisture and weak upslope flow translates to a nearly zero chance for precipitation today. Therefore, NO 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, Urban Corridor, Palmer Ridge, Northeast Plains, Southeast Plains, Raton Ridge & Southeast Mountains:

Aside from some fair-weather cumulus today, it is expected to be warm, clear, and pleasant over the eastern half of the state. No precipitation is forecast, so NO flood threat has been issued.

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

Increasing high temperatures and another day of dry conditions can be expected. Incoming mid and upper-level clouds are forecast to cross over the western border later this afternoon. Outside of a few sprinkles being possible over the eastern San Juan Mountains late this afternoon, rainfall is not forecast. NO flood threat has been issued.