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.