Issue Date: Sunday, June 14th, 2020
Issue Time: 8:55AM MDT

— Flooding is NOT expected today

Sunny, hot, windy, and mostly dry conditions are expected over Colorado today. The majority of the state has already moved into the dry slot portion of the current system, which can be seen by the yellow shade over the state in the water vapor imagery below. There is still a bit of moisture and lift over eastern Colorado, so it’s pretty cloudy over the border counties this morning. High surface winds are expected today, which means high fire danger when paired with the dry mass across the state. This increase in wind is due both to the upper level jet over western/central Colorado and a developing lee trough over the northeast plains. Therefore, a majority of the moisture over the eastern plains is expected mix out east (green arrow) by early afternoon with the dry southwesterly flow. One or two weak thunderstorms or quick rain showers may develop over the eastern plains with the minimal residual moisture as some mid-level vorticity (lift) passes overhead this afternoon. However, storms are expected to be high-based and produce little rainfall, so flooding is not forecast. The main threat from the few storms that are able to develop will be very strong outflow winds (45 to 55 mph).

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

One or two dry thunderstorms will be possible this afternoon over the Southeast Mountains and western Raton Ridge. However, chances won’t be great for storm development with the fast winds and low moisture environment. Best chance for a storm or two will be over the far eastern plains where temperatures will near 100F. The best chance for any rainfall will be over the Southeast Plains. Max 1-hour rain rates up to 0.15 inches (south) and 0.10 inches (north) will be possible, but most storms will produce only virga. Strong outflow winds will likely develop with any thunderstorm that can form, so 45 to 55 mph gusts will be possible over the eastern plains. A Red Flag Warning has been issued for the Southeast Plains and portions of the Northeast Plains and northern Southeast Mountains. Tune into your NWS office for the latest on today’s fire danger.

Primetime: 2PM to 10PM

Front Range, Central Mountains, San Juan Mountains, Northern Mountains, Northwest Slope, Grand Valley, San Luis Valley, Southwest Slope, Urban Corridor, & Palmer Ridge:

Dry, hot, and windy conditions are expected by midday for these regions. Highs will reach the upper 80Fs to low 90Fs over the lower elevations and valleys, and highs over the mountain valleys will be in the mid-70Fs.  A large portion of these regions are placed under a Red Flag Warning due to increasing southwesterly surface winds that are forecast today. Surface winds are forecast to be in the 15 to 25 mph range with gusts up to 40 to 50 mph possible. Be sure to tune into your NWS office for the latest on the fire weather front. Decoupling with the upper atmosphere will occur around sundown, so that’s about the time the surface winds will relax.

Issue Date: Saturday, June 13th, 2020
Issue Time: 9:25AM MDT

— A LOW flood threat has been issued for the 416 and Decker burn areas

We’ll start this forecast by taking at a look at the mid-level atmospheric set up below (500 mb). Today, the Low that has been in the Gulf of Alaska moves inland and merges with the shortwave that was off the coast of California. As this joining happens over the Pacific Northwest, vorticity and faster wind speeds (purple oval) will move into western and central Colorado, which will help provide upper dynamic support (lift) for storms this afternoon and evening favoring the high terrains. Flow aloft, which helps set the steering winds for storms, will be increasingly southwesterly over western/central Colorado and gain a slight westerly component over the foothills and adjacent plains in eastern Colorado. Moisture has also been making its way into the state, and PW values this morning we measured at 0.57 and 0.63 inches in Grand Junction and Denver, respectively. This moisture is expected to increase throughout the day, which is something we are already seeing near the southwest border.

This set up will help spark fairly widespread showers and thunderstorms over the high terrains this afternoon with storm movement towards the northeast. As the storms move off the Southeast Mountains and Front Range, they will start to gain a westerly component. This should bring some rainfall to the Urban Corridor and adjacent plains as well, but at that time, storms will likely become outflow driven and produce more wind and less rainfall. Trailing storms over the mountains will likely help increase 24-hour totals over Central and San Juan Mountains, but only up to moderate rainfall is forecast for the individual storms. Therefore, no flood threat is forecast with the exception of a couple burn areas.

The first threat is for the 416 burn area as isolated totals by morning near the area have the potential to reach 0.75 inches. While this atmospheric set up will likely have that area of higher precipitation closer to the Continental Divide, a Low flood threat has been issued. The second Low threat is issued for the fresh Decker burn area. Although storms will be less widespread over the Southeast Mountains, storms will have the ability to produce rain rates up to 0.50 inches. This could cause flash flooding issues over the burn area if a storm tracks overhead.

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, Central Mountains, San Juan Mountains, & Northern Mountains:

Best chance for storms this afternoon and evening will be over the mountains. Higher rain rates and totals are expected over the San Juan Mountains, Central Mountains and Front Range near and along the Continental Divide. Wetting storms are forecast to be more widespread over the San Juans and Central Mountains. Max 1-hour rain rates up to 0.50 inches will be possible over the higher terrains with totals up to 0.75 inches by morning in the Central and San Juan Mountains. Stronger thunderstorms will also likely produce some gusty outflow winds/small hail, and more wetting rainfall is forecast later this afternoon and evening. A Low flood threat has been issued for the 416 and Decker burn area. The flood threat will end later this evening with a couple light showers lingering into the night over the San Juans.

Primetime: 1PM to 11PM

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

A few weak storms will be possible over the Southwest Slope and San Luis Valley due to better moisture and lift in the area as storms move in from the south. However, storms will likely produce gusty outflow winds (around 40 mph) as they move into these lower elevations. Max totals up to 0.10 inches will be possible with most areas only receiving a few sprinkles. As storms move into the adjacent eastern plains this afternoon and evening the main threat will be strong winds. Max 1-hour rain rates up to 0.20 inches (north) and 0.15 inches (south) are forecast. Rainfall should come to an end around midnight.

Over the lower elevations of extreme western Colorado and the Southeast Plains increasing surface winds and low relative humidity will combine for critical fire weather. Please tune into your local NWS office for the latest on the Red Flag Warnings that have been issued.

Primetime: 1PM to 1AM

Issue Date: Friday, June 12th, 2020
Issue Time: 9:05AM MDT

— Flooding is NOT expected today

To our west you can see the lift and moisture associated with the next system, which will start to progress eastward today. Over Colorado, mid-level moisture and energy will begin to make its way northward around the High marked below (green “X”). From today into tomorrow, expecting that moisture to increase, which will bring afternoon storms back to the mountains and immediate adjacent plains. However, for the time being, moisture still remains limited. That means only high-based showers and weak, dry thunderstorms are forecast over the southern high terrains this afternoon and evening. With the boundary layer still being quite dry, storms are expected to produce strong winds and limited rainfall.

As the storms rotate clockwise around the high, a storm or two may be able to survive over the western Palmer Ridge due to enhanced convergence over the area. A couple additional storms may form along and south of the Raton Ridge with the southerly surface flow, but storms are expected to move south of the border with the steering flow. Most activity should end a couple hours after the sunsets (decreasing instability), but a weak shower is possible over the San Juan Mountains tonight or early tomorrow morning with mid-level energy rotating around the High. 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, Central Mountains, San Juan Mountains, Raton Ridge, & Palmer Ridge:

A couple high-based, dry thunderstorms will be possible this afternoon over the San Juan and southern Central Mountains. With instability a bit higher over the area and a large dew point depression, some strong outflow winds will be possible with storms that form (up to 45 mph). Very isolated max 1-hour rain rates up to 0.25 inches will be possible with most storms producing totals between 0.10 and 0.15 inches. Moisture over the mountains won’t be quite as high east of the Continental Divide, so max 1-hour rain rates will drop to 0.15 inches and coverage will decrease. Gusty winds will still be possible as storms dissipate, but chances for severe winds drop when compared to western high terrains. Storms that form over the western Palmer Ridge and Raton Ridge will be able to produce totals up to 0.25 inches. Flooding is not forecast.

Primetime: 12:30PM to 10PM

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

It’ll be another hot, dry day with temperatures increasing once again. Highs are forecast to reach the upper 80Fs to mid-90Fs over the valleys and the mountain valleys should reach the mid-70Fs. Rainfall is not forecast, but cloud cover will increase from the west with the next system moving east.

Urban Corridor, Southeast Plains, & Northeast Plains:

A dry, hot day is in store for these regions as well with very little cloud cover forecast this afternoon. Highs will reach the upper 80Fs to 90F along the Urban Corridor with mid-90Fs possible over the Southeast Plains.

Issue Date: Thursday, June 11, 2020
Issue Time: 9:15AM MDT

— Flooding is NOT expected today

Folks across the state awoke to a cloud-free morning on this Thursday, a preview for the rest of the day. As shown in the water vapor image, below, a ridge axis is in place over the Four Corners region. This ridge will intensify notably today, with 500-mb heights rising by roughly 60 meters over the next 12-18 hours. As such, mid-level subsidence will occur statewide. In combination with low moisture, this implies a mostly sunny day for almost everyone. The only exception will be in the far southeast corner of the state, where slightly higher moisture content could result in an isolated storm. With dewpoint depressions approaching 60 degrees F (!), anyone who sees even a drop of rain should consider themselves lucky. More likely would be gusty downdraft winds, as downdraft CAPE is expected to exceed 1,000 J/kg should a storm hang around long enough.

Elsewhere, the very low humidity levels will combine with gusty afternoon winds to elevate the wildfire threat yet again over the San Luis Valley, Southeast Mountains and Raton Ridge.

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, Front Range, Palmer Ridge, Urban Corridor, Central Mountains, Northwest Slope, Grand Valley, Northwest Slope, Southwest Slope, San Juan Mountains:

Sunny and warmer today with temperatures near seasonal normal. Flooding is NOT expected today.

San Luis Valley, Southeast Mountains, Raton Ridge, Southeast Plains:

Sunny and warmer today with temperatures slightly above seasonal normal. An isolated thunderstorm is possible over far southeast areas, towards the Kansas and Oklahoma borders. Max 1-hr rainfall up to 0.20 inches along with gusty winds possible. Gusty winds are also expected to develop over the higher terrain this afternoon, which will cause an elevated fire threat. Flooding is NOT expected today.