Issue Date: Saturday, July 10th, 2021
Issue Time: 8AM MDT

— Flooding is NOT expected today

The departing trough to the east (orange X’s) dropped a cold front across the state overnight, so it’s a cooler start to the day for the northern tier of the state. There was also a slight uptick in dew points behind the front over eastern Colorado. PW at Denver rose to 0.82 inches, but this morning’s sounding also shows a strong inversion (cap) at 600mb. This should help to keep rainfall chances close to nil this afternoon and evening over the area. Best chance for a sprinkle or two will be over the Southeast Mountains near the southern border.

It’s a smokey start over the lower elevations of western Colorado. Near surface smoke is forecast to increase across the Northern/Central Mountains this afternoon due to the location of High (northerly surface winds). As the High moved slightly to the west over the last 24-hours, a much drier air mass has moved into the region. PW at Grand Junction has dropped to 0.30 inches, which means rainfall is not expected this afternoon. Although weaker than yesterday, there’s still a small pocket of weak moisture across the southern border. This may allow for an isolated, weak storm or two to develop over the southern San Juan Mountains near the border. 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:

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

Another Heat Advisory has been issued, but this time it’s for the lower elevations of the Southwest Slope (SW corner of the state). High temperatures are expected to reach just over 100F over this region, which is also true of the Grand Valley. Slightly cooler highs in the low to mid-90Fs are forecast over the Northwest Slope and mountain valleys. So, it remains hot over these regions. A stray storm or two could pop over the southern San Juan Mountains near the border, and rain rates up to 0.25 inches per hour would be possible. Flooding is NOT forecast.

Primetime: 2PM to 7PM

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

The mid-level inversion should keep a lid on the chances for convection this afternoon. Some afternoon cloud cover is forecast over the mountains, which will help provide a little relief from the heat. These cloud bases may produce a sprinkle or two (south), but virga is the more likely scenario. A stray storm way wander into the Northeast Plains from Nebraska, but the likelihood of this happening is low. Max 1-hour rain rates up to 0.40 inches would be possible. Overall, it should be a beautiful day over eastern Colorado and the San Luis Valley. Flooding is NOT forecast.

Issue Date: Friday, July 9th, 2021
Issue Time: 9:15AM MDT

— Flooding is NOT expected today

It’s going to be a scorcher today with the 5940m height over the state. High temperatures across the lower elevations of the Grand Valley are forecast to reach 100-105F, so a Heat Advisory has been issued. Also noticeable in the visible satellite imagery below are lots of smoke plumes from the ongoing fires across the west. Guidance indicates some modest near surface smoke will move into the Northwest Slope and Grand Valley this evening and overnight.

A shortwave, currently located over Idaho, is expected to rotate around the High today, which will push the High west but will also help provide some extra lift for thunderstorm development out in front of it. As far as rainfall chances, PW at Grand Junction and Denver was measured at 0.80 and 0.70 inches, respectively. Much of this moisture is in the mid-levels of the atmosphere, so with a large spread between dew points and temperature near the surface, the main threat from the high-based storms that fire this afternoon and evening will be strong outflow winds again. With PW increasing to 1.11 inches over North Platte, NE, more measurable rainfall is anticipated for storms as they move into the Northeast Plains and far eastern border counties. A jet, accompanying the shortwave, should keep storms moving at ~20 mph to the southeast, which will limit the flood threat today. Additionally, the extra dynamics over the Northeast Plains may help produce an isolated severe thunderstorm or two late this afternoon into this evening. Flooding is NOT expected today.

Overnight a cold front drops in from the north over eastern Colorado, which could produce some very strong gusts over the foothills and I-25 Corridor as it moves south.

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, Palmer Ridge & Southeast Plains: 

Scattered storms are expected to move into these areas by mid-afternoon (north) and early evening (south) as the shortwave makes it way east. The earlier storms, to the north, are expected fire over the Cheyenne Ridge and move across the border with the northwest steering flow. With the jet and shortwave overhead, an isolated, low-end severe thunderstorm or two may be possible over the far northeast corner of the state. Faster steering flow should limit the heavy rainfall threat today with max 1-hour rain rates up to 1 inch possible. Further south, storms will move into the area later this afternoon into this evening. There is less of a risk for any severe thunderstorm development, but storms could produce some very strong outflow winds. Max 1-hour rain rates up to 0.75 inches will be possible. Due to the faster steering flows, flooding is NOT forecast today. Strong winds could develop late tonight as the cold front drops south through eastern Colorado.

Primetime: 3:30PM to 11PM

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

Daily high temperature records may be broken today, so be sure to carry water with you if you’re outside. Scattered storms should fire over the elevated ridges and eastern mountains by early afternoon. Better coverage of storms looks to be south over the Southeast Mountains and across the southern Front Range. High storm bases will limit the rainfall potential with max 1-hour rain rates up to 0.20 inches forecast. The main threat from storms that develop this afternoon is expected to be gusty outflow winds again. Flooding is NOT forecast. Strong wind gusts overnight (up to 55mph) will be possible across the I-25 Corridor and foothills as the next cold front drops south.

Primetime: 1:30PM to 8:30PM

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

A Heat Advisory has been issued for the lower elevations of the Southwest Slope and Grand Valley today. Hot temperatures, low relative humidity and increasing surface winds will also cause an uptick in fire danger north. A Red Flag Warning has been issued for the Northwest Slope. Best chance for measurable rainfall will be over the San Juan Mountains again where a little better moisture can hang on. Storms are expected to be scattered in nature and only produce isolated rain totals around 0.15 inches, so flooding is NOT anticipated.

Primetime: 1PM to 8:30PM

Issue Date: Thursday, July 8th, 2021
Issue Time: 8:55AM MDT

— Flooding is NOT expected today

Gradual drying of the atmospheric column continues over Colorado today with PW dropping to 0.63 and 0.66 inches at Grand Junction and Denver, respectively. More importantly, the boundary layer continues to dry with dewpoint temperatures falling about 2-5F compared to yesterday morning. As shown in the visible satellite image, below, a deck of mid-level clouds was noted along the UT border from a weak disturbance. However, with mid-level temperatures continuing to warm today, instability will be limited with rainfall having a difficult time making it to the ground. The best chances for light showers and isolated weak storms will be over the higher terrain, especially over southern Colorado. Gusty winds will likely accompany any stronger storm that does manage to form. However, flooding is NOT expected today.

The big story today will be the return to much above normal temperatures, pushing above 100F below 5,000 feet. For reference, the record high temperature today in Grand Junction is 104F, while Denver’s is 103F. Both sites have very long periods of record dating back to the late 1800s, so any records would be impressive.

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, San Juan Mountains, Southeast Mountains, Front Range and Palmer Ridge:

Isolated to widely scattered showers and thunderstorms this afternoon and evening. Max 1-hour rainfall up to 0.3 inches north of I-70 and 0.6 inches south of I-70 especially towards the New Mexico border. Gusty winds will accompany the strongest storms. Flooding is NOT expected today.

Primetime: 12pm to 9pm

Urban Corridor, Northeast Plains, Southeast Plains, Raton Ridge and San Luis Valley:

Very hot with isolated showers and perhaps a weak storm possible this afternoon and evening. Gusty winds will be possible with any stronger storm. Max 1-hour rainfall up to 0.3 inches. Flooding is NOT expected today.

Primetime: 2pm to 10pm

Northwest Slope, Grand Valley and Southwest Slope:

Very hot today with mostly dry conditions. An isolated shower or storm cannot be ruled out especially in the foothills. Max 1-hour rainfall up to 0.2 inches. Winds will pick up this afternoon, and a Red Flag Warning has been posted for parts of the region.

Issue Date: Wednesday, July 7th, 2021
Issue Time: 9:10AM MDT

— Flooding is NOT expected today

High surface moisture and cool temperatures over the far eastern plains are helping to create some dense fog this morning. This should burn off by late morning with a little heating from the strong July sunshine. While dew points are still greater than 55F to the east of the green dashed line below, the morning sounding at Denver shows much drier conditions above ~700mb. That means that as the day continues, the surface moisture should have an easier time mixing out of the boundary layer. PW was measured at 0.74 inches and 0.66 inches at Denver and Grand Junction, respectively, which are lower than yesterday. So, with this drier air mass establishing itself over the state, a break from heavy rainfall is anticipated today. The eastward moving ridge will also aid in supporting subsidence (sinking) and warming temperatures.

Best chance for measurable rainfall today will exist along the southern border over the higher terrains. Isolated storms may drop small pockets of rainfall up to 0.25 inches. Weaker storms will also be possible along and near the Continental Divide, although accumulations should stay under 0.10 inches and most storms will only produce cloud cover and virga. This break in rainfall is very welcome as it will allow soils over the mountains to dry out, which have received quite a bit of precipitation over the last week or so. As anticipated, 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:

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

Highs over the lower elevations will reach into the upper 80Fs and low 90Fs with mid 80Fs forecast for the elevated ridges. Mountain valleys will reach into the upper 70Fs and low 80Fs. With plenty of sunshine and only a few isolated, weak storms forecast, it’s going to be a beautiful day ahead. Best chance for measurable rainfall will be over the Southeast Mountains/Raton Ridge intersect where isolated rain totals up to 0.25 inches will be possible. Flooding is NOT forecast today.

Primetime: 3PM to 7PM

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

Hot temperatures are again forecast over the lower elevations of the Southwest Slope and Grand Valley, and highs could reach 100F. Other lower elevation valleys are expected to reach up to 90F with upper 80Fs forecast for the mountain valleys. Best chance for isolated, weak storm or two will be over the southern San Juan Mountains. A quick 0.25 inches could fall with the fast-moving storms, but flooding is NOT forecast.

Primetime: 2:30PM to 9PM