Issue Date: Wednesday, May 13th, 2020
Issue Time: 8:25AM MDT

— Flooding is NOT expected today

WSW flow aloft continues to pull in a very dry air mass as indicated by PW measurements in Grand Junction and Denver – 0.26 inches. Visually, this dry air can be seen by the cloud free conditions in the satellite image below. There is cloud cover east of the Continental Divide and some dense fog being reported over the far eastern plains, but this is expected to mix out rather quickly. Westerly flow aloft will produce a surface low over eastern Colorado, which will help increase surface speeds and produce Red Flag conditions across southern Colorado. Outside of scattered, light rainfall over the northwestern Colorado border late this afternoon (passing shortwave to our north), rainfall is not forecast today. A weak cold front drops through the state overnight, and will increase moisture behind it. That should set the stage for storms to return tomorrow afternoon over northwestern and eastern Colorado.

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:

Northwest Slope, Northern Mountains, & Central Mountains:

Temperatures will reach around 70F for the lower elevations of the Northwest Slope and 60F over the mountain towns. A passing shortwave to the north of the state may produce some light showers over the northern border. Best chance for accumulation will be the Northern Mountains (Routt and Jackson County) where very isolated totals up to 0.20 inches may be possible. Expect lower amounts and some wind over Moffat County. Flooding is not forecast.

Primetime: 2:30PM to 9PM

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

A Red Flag Warning has been issued through this evening for most of the regions mentioned above. The only exception is the San Juan Mountains where surface winds won’t quite meet warning criteria. Over western Colorado, southwest surface winds are forecast to reach 15 to 25 mph with gusts up to 35 mph. Forecasting similar winds for southeast Colorado, but lower relative humidity values (single digits); thus, increased danger. With temperatures in the 80Fs and plenty of dry fuels, fires will be able to spread quickly. Please use caution with anything that can cause a spark, and tune into your local NWS office for more information.

Urban Corridor, Northeast Plains, & Palmer Ridge:

Starting to heat up once again with highs in the 80Fs forecast. Broken cloud cover this afternoon should help provide a little respite from the heat. With a dry air mass in place and downsloping winds, rainfall is not forecast.

Issue Date: Tuesday, May 12th, 2020
Issue Time: 8:40AM MDT

— Flooding is NOT expected today

The water vapor imagery below shows a dry air mass over the Desert Southwest that will start to move into the state from the west today. PW at Grand Junction has already dropped to 0.45 inches, which is about a quarter inch below yesterday morning. As this dry flow moves west across the state, it will help to mix out the cloud cover and fog over eastern Colorado by midday. It may be slow to reach the far eastern plains, so expecting cooler temperatures east when compared to the Urban Corridor.

Today is expected to be a quiet weather day when compared to yesterday with the main center of lift (orange “X”) staying north and west. Embedded in the westerly flow are some weak shortwaves, so late afternoon cloud cover is forecast for the state. However, it will be too dry for clouds to produce more than shade and a sprinkle or two. The one exception is over the Palmer Ridge where there may be some residual moisture. Surface convergence may allow for a couple, very weak storms to form this afternoon, but storms are expected to be high-based and produce more gusts than rainfall. 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:

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

Lots of fog and cloud cover to start the morning with light rainfall being reported at Colorado Springs (8AM). This should burn off (west) by noon and temperatures are expected to reach the 70Fs with higher temperatures south. It will be a bit cooler out east with highs in the low 60Fs, which will nix chances for afternoon storms. A couple, weak storms may pop up over the Palmer Ridge with max 1-hour rain rates up to 0.15 inches possible. The more likely scenario is gusty outflow winds and a little lightning.

Primetime: 1PM to 8:30PM

Grand Valley, San Luis Valley, & Southwest Slope:

A Red Flag Warning has been issued from noon today through 9PM tonight. Southwest wind gusts are forecast to exceed the 25 mph mark and the dry air entrainment will produced relative humidity values around and just under 15%. This makes conditions favorable for fire spread and growth, so use caution with open flames and avoid burning. Tune into you local NWS office for more information. Highs this afternoon are forecast to be in the 80Fs for the valleys and around 70F elsewhere.

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

Increasing cloud cover is forecast this afternoon, but rainfall is not forecast. Temperatures be more seasonable when compared to yesterday. Surface winds will pick up from the southwest this afternoon, so elevated fire conditions are forecast for the Northwest Slope. Brief gusty winds can be expected over the high country. Overall it’s shaping up to be a gorgeous spring day.

Issue Date: Monday, May 11th, 2020
Issue Time: 9:30AM MDT

— A LOW flood threat has been issued for the Lake Christine burn area

Moisture from the south has returned to the state, which can be seen by the abundant cloud cover in the image below. Precipitable Water was measured at 0.68 inches in Grand Junction this morning, which is very much above normal for this time of year. This moisture, paired with a vorticity maximum (lift) moving through the ridge pattern, helped produce some overnight rainfall for western Colorado and the mountains. Expecting this rainfall to continue throughout the day with increased intensity due to the stronger moisture in place. A couple thunderstorms are also possible over western Colorado and the mountains as instability increases with day time heating. Mountain valleys will likely see no to light accumulations and brief windy conditions.

As storms move off the Southeast Mountains and Front Range, expecting accumulation to favor the Palmer and Raton Ridges. Southeast surface flow will also help pond higher moisture over the Southeast Plains, so if storms make it into this area, a couple strong storms can be anticipated. The Northeast Plains will remain capped (no rainfall) with much below average temperatures.

Overall, this is a classic Colorado spring weather system with an assortment of precipitation types. Not too worried about saturated soils over western Colorado due to the recent dryness, spring green up, and low accumulations from yesterday. Also, the more stratiform nature of the general rainfall pattern should keep the flood threat low statewide. With the warmer temperatures, a lot of the low elevation snow pack has melted out, so rain on snow isn’t a huge concern either. However, there is the possibility for afternoon thunderstorms to spring up over the Central Mountains, and one of these stronger storms tracking over the Lake Christine burn area. A Low flood threat has been issued for this burn area for this reason.

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:

Urban Corridor, Northeast Plains, Palmer Ridge, Southeast Plains, & Raton Ridge:

Cold start to the morning with the Northeast Plains reaching near freezing values. This area should remain rain free today with below average high temperatures. Increasing southeast surface winds will help pull some higher moisture values into the Southeast Plains. Expecting storms to favor the Palmer and Raton Ridges as the move off the mountains. A stronger thunderstorm or two may be possible over the far Southeast Plains. One to two hour totals up to 0.6 inches (west) and 1 inch (east) are forecast, but flooding is not expected.

Front Range, Northern Mountains, Central Mountains, Southeast Mountains, San Juan Mountains, & San Luis Valley:

Expecting rainfall coverage to grow throughout the day with intensity increasing from yesterday. Mountain valleys should remain dry, which includes the San Luis Valley. Brief gusty winds may also be possible in these areas. The snow line is forecast between 10K to 11K with 2-4 inches expected by morning. Generally, more stratiform rain is forecast with totals by morning between 0.5 and 0.75 inches. Isolated totals up to 1 inch may be possible over the Front Range and Northern Mountains near the Continental Divide. Over the western high terrains spotty afternoon thunderstorms are anticipated with max 1-hour rain rates up to 0.6 inches. If one of these storms tracks over the Lake Christine burn area, flash flooding, mud flows and debris slides will be possible. A Low flood threat has been issued for this reason.

Northwest Slope, Grand Valley, & Southwest Slope:

Coverage of rainfall and afternoon storms will be more spotty over these regions. Max 1-hour rain rates up to 0.6 inches will be possible over the high elevations in these regions under the stronger storms. Overall, totals will be between 0.10 and 0.25 inches with brief gusty winds possible. Flooding is not forecast.

Issue Date: 5/10/2020
Issue Time: 8:10 AM

— Flooding is NOT expected today

The northwesterly flow aloft that has controlled the forecast the last few days will begin to give way to more westerly flow today. This will allow mid-level moisture to return from the west this afternoon/evening (green arrows in image below), and then south/southwesterly flow in the low-levels will start to bring in moisture from the south tonight and tomorrow. Today’s moisture return will mainly prime the atmosphere for tomorrow, but there will be enough to fuel scattered high-based showers, and perhaps a thunderstorm or two.

Generally speaking, the scattered showers/weak thunderstorms will remain over the High Country, especially west of the Continental Divide, where the moisture will be first to return. The activity will be high-based, with low-level moisture still lacking, resulting in mainly gusty winds and light, if any, rainfall reaching the surface. Bigger changes come overnight and tomorrow morning, when a better surge of moisture reaches western Colorado and the added instability brings a few more claps of thunder and better rainfall. Still, not enough to result in a flood threat during this forecast period.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. 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

Urban Corridor, Palmer Ridge, Northeast Plains, Southeast Plains, and Raton Ridge:

Sunshine and warmer temperatures will dominate the forecast today, with clouds increasing overnight and tomorrow morning as the moisture returns. There is a chance for an isolated thunderstorm or two over the Raton Ridge and far Southeast Plains this afternoon/tonight as surface moisture tries to cross the Raton Ridge into southern Colorado. Rainfall rates from any activity will be less than 0.25 inches/hour.

Timing: 3 PM – 9 PM

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

Today begins on a mostly sunny note, but moisture is making its return today, and clouds will increase along with it as the day goes on. Scattered, high-based showers/weak thunderstorms will rumble across the region, especially west of the Continental Divide, beginning early this afternoon and continuing into tomorrow. Rain rates will generally be light, as moisture will still be lacking in the low-levels during this forecast period. The main impacts from any activity will be gusty winds and lightning. Rain rates will be less than 0.2 inches/hour this afternoon/evening, with better rainfall to the tune of 0.2-0.4 inches/hour tomorrow morning as the better moisture surge arrives.

Timing: 1 PM – 11 AM for the Southwest Slope, San Juan Mountains, and San Luis Valley; 3 PM – 11 AM for Grand Valley and Central Mountains, 4 PM – 11 AM for the Northwest Slope and Northern Mountains; 3 PM – 10 PM for the Southeast Mountains; 4 PM – Midnight for the Front Range