FTB 09-26-2020: Expanding Fire Danger

Issue Date: Saturday, September 26th, 2020
Issue Time: 8:45AM MDT

— Flooding is NOT expected today

Zonal flow will continue over the state today, and increasing westerly flow is forecast as a stronger and larger jet streak sets up to our north. This will expand the elevated fire weather danger across the state to the area in pink below. In the visible satellite imagery, you can also see a lot of mid and high-level cloud cover over the state and to our north from this system. However, outside of some light showers over Montana and northwest Wyoming, no precipitation is occurring. This is a testament to how little moisture is linked to this system, and PW solidifies this statement at it was measured slightly below 0.40 inches. That means that it’s too dry for any rainfall to develop today, and additionally, there will be no upper level dynamics to help with lift. Without these two key ingredients for rainfall, expect only increasing cloud cover throughout the today.

Wind speeds have already picked up over the northern Front Range and gusts up to 40 mph are being observed. The highest gust over the last hour was at always windy Berthoud Pass (~65 mph). A Red Flag Warning is in place for the majority of the state, and full details for your area can be found from your local NWS office with limited information below. Gusty conditions may affect ongoing fires, especially the Cameron Peak fire, so stay tuned to your local emergency management.

Tonight, a cold front will drop through the state, which will be marked by a shift to northerly winds. Best chances for higher gusts along the front will be over the far Southeast Plains (up to 45 mph). A few sprinkles may occur along the front, but measurable rainfall is not forecast. Cooler conditions are expected for tomorrow for the majority of the state.

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, Palmer Ridge, Northern Mountains, Central Mountains, Grand Valley, Northwest Slope, Urban Corridor, & Northeast Plains:

The regions will be dealing with most of the Red Flag Warnings issued today. It’s going to be breezy with stronger gusts forecast for the mountains. More or less, west winds between 15 and 25 mph are forecast (gusts between 40 and 50 mph possible) for the higher elevations and Grand Valley. Slightly lower winds are expected over the Urban Corridor and Northeast Plains with northwest winds forecast in the 10 to 20 mph range (gusts up to 30 mph). As far a high temperatures this afternoon, it’s a repeat forecast of yesterday. Precipitation is not forecast.

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

Pockets of elevated fire conditions are forecast today, so be sure to tune into your local NWS office to see if your area has one issued. Over the Southeast Mountains, westerly winds between 20 and 30 mph are forecast with gusts up to 45 mph possible. Over the SLV, west winds between 15 and 25 mph are forecast with gusts up to 35 mph possible. It’s too dry for any rainfall to develop, and high temperatures will be similar to yesterday. As the front passes over the Southeast Plains late tonight, strong northerly wind gusts may be possible.

FTB 09-25-2020: Critical & Elevated Fire Conditions

Issue Date: Friday, September 25th, 2020
Issue Time: 9:20AM MDT

— Flooding is NOT expected today

The 500mb High and associated ridge have been pushed south and flow has become more zonal across the state. Increasing, dry westerly flow throughout the day is anticipated as a jet streak establishes itself to our north. This will create downsloping winds, which will help increase high temperatures to the east, and it will also cause an uptick in surface winds. Increased southwest/west surface winds paired with low moisture and above average temperatures will cause critical and elevated fire conditions, making this is the main weather concern today (pink dashed area below). A Red Flag Warning has been issued for the northern mountains and northern half of the western slope for winds in the 15 to 25 mph range and gusts up to 40 mph. Strong vertical mixing will reduce any remaining moisture out of the lower half of the atmosphere, so rainfall 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:

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

Northerly surface winds associated with the trough to our east (shown by the current cloud cover over the eastern plains) will help push out near surface smoke this morning over northeast Colorado. Throughout the day the surface winds will become more easterly, so an increase in smoke is anticipated again late this afternoon. Without much moisture, and further drying with the downsloping winds, rainfall is not forecast. High temperatures are expected to slightly increase this afternoon as the westerly flow will cause adiabatic compression, so another 90F degree day is possible. Please follow your local NWS office for the latest on Red Flag Warnings issued for these regions as they may cause the ongoing fires to flare up.

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

The main weather story today is increased fire weather concerns for these northern regions as the jet dips across the northern border. A Red Flag Warning has been issued, and you can follow the latest details from your local NWS office. High temperatures should be similar to yesterday, but breezy conditions may make it feel a bit cooler. With strong vertical mixing, any remaining boundary layer moisture will perish, so rainfall is not forecast. As the next trough moves onshore, lift out in front of it (orange “X”) will cause an increase in cloud cover late this afternoon.

FTB 09-24-2020: Dry Conditions & Above Average Temperatures

Issue Date: Thursday, September 24th, 2020
Issue Time: 9AM MDT

— Flooding is NOT expected today

Behind the departing trough on Wednesday, a much drier air mass filled in over the state as the ridge began to build (yellow in the image below). PW values corroborate this change and have dropped off since this time yesterday, measuring 0.45 and 0.53 inches at Denver and Grand Junction, respectively. As the High begins to move eastward throughout the day, Colorado will remain under its influence. So, this means dry conditions and above average temperatures.

The incoming shortwave (orange “X”) is providing some lift and increased moisture in a bit of a dirty ridge pattern, but the majority of this upper level cloud cover is north of the state and is producing no rainfall. The tail end of this feature is dipping into the northwest corner of the state and producing some cloud cover, but it’s already beginning to break up with a little heating. This feature will slowly track southeast today, which provide nothing more than broken cloud cover over the mountains. With the dry air mass well intact and subsidence around this feature continuing, rainfall 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:

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

Outside of broken, upper level cloud cover from the aforementioned feature, clear conditions are forecast today. Temperatures will also continue to be above normal with highs likely reaching 90F over the lower elevations. Over the mountains, temperatures will be about 10-15F cooler than that, so still warm. With upper level steering flow becoming more northerly, near surface smoke may increase over the Northeast Plains and Urban Corridor as well. Rainfall is not forecast.

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

It’s going to stay warm today with highs in the valleys reaching the upper 80Fs and mountain valleys reaching the 70Fs. The dry air mass and building High means there is no rainfall forecast. An upper level jet associated with the incoming trough may help produce some stronger winds over the northwest corner of the state. Wind speeds between 15 and 20 mph should be expected this afternoon with gusts slightly higher. Expect near surface winds to continue to increase and expand in coverage over the next couple of days. No rainfall is forecast today.

FTB 09-23-2020: Weak Convective Showers for Southern Mountains

Issue Date: Wednesday, September 23rd, 2020
Issue Time: 09:55AM MDT

— Flooding is NOT expected today

Today Colorado is between large-scale drivers of weather as the mid-level high pressure dome is centered along the southern California coast and post-tropical cyclone Beta swirls over southeastern Texas (see image below). An elongated area of clouds & showers associated with some mid-level lift stretches from central Colorado northeast into the Dakotas. This does not appear to be associated with a well-defined Low pressure system, but rather just mid-level convergence in the upper-level flow. Mid-level winds are more northwesterly/northerly to the west of this elongated feature, whereas southwesterly winds exist within it. This bit of energy is moving its way eastward out of the state, and it will create some weak showers over the northern plains regions this morning and afternoon. Mid- and upper-level moisture remains over the state as PW from the Denver (Grand Junction) morning sounding shows 0.63 (0.66) inches, similar to yesterday. Surface dew points are near 40F for most low-elevation locations across the state, increasing to the mid 40Fs along eastern Colorado. Daytime heating will allow some weak instability to build, which will initiate some convective showers and maybe a thunderstorm over the mountains south of I-70. This convective precipitation should remain weak and high-based, so mainly gusty winds are expected. No flooding is expected today.

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:

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

Some morning showers and clouds will begin the day for the northern half of the plains regions, but little rainfall is expected. Some convective showers could drift off the higher elevations this afternoon into the adjacent plains, but limited moisture will keep rain rates below 0.2 in/hr. Temperatures will again climb well above average into the mid and upper 80Fs, which will keep surface relative humidity low (10-20%) and favor plenty of evaporation for any showers that do move over the area. This evaporation will allow gusty winds up to 40 mph to be generated from showers as they dissipate. No flooding is expected today.

Some smoke from the active Mullen, Middle Fork, and Cameron Peak wildfires may be transported into the northern Urban Corridor and Northeast Plains today. The NWS has an Air Quality Alert in place over this area. See your local NWS for more information.

Primetime: 10AM to 8PM

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

Convective showers are possible for most mountain regions, but chances for accumulating rainfall largely exists south of I-70. Rain rates should stay below 0.2 in/hr with these showers due to the limited moisture and high-bases, which will favor plenty of evaporation and gusty winds up to 40 mph. The southern Front Range and Southeast Mountains have the highest chances for showers and possibly a weak thunderstorm. Some moderate 20 mph mid-level north/northwest flow should keep showers moving, limiting total rain accumulations to under 0.3 inches by morning. No flooding is expected today.

The valley locations along western Colorado should stay dry and warm today, with high temperatures reaching into the low 80Fs. Smoke levels may increase as westerly/northwesterly winds transport west coast wildfire smoke into the state.

Primetime: 12PM to 8PM