FTB 09-30-2020: Dry with Ample Sunshine to End the FTB Season

Issue Date: Wednesday, September 30th, 2020
Issue Time: 9:50AM MDT

This is the last scheduled Flood Threat Bulletin for the 2020 season. Once again, it has been a pleasure to serve you! The next Flood Threat Bulletin season begins on May 1, 2021.

— Flooding is NOT expected today

A very dry air mass has worked its way over the western US and Colorado under an impressive dual High pressure ridge (yellow/orange shades below). Under this set up, northwesterly flow aloft will continue with the core of the jet to our northeast. The jet may nose into the far Northeast Plains, so surface winds in the 15 to 20 mph range will be possible over the border counties.

A shallow cold front is currently moving through eastern Colorado, so more seasonable temperatures are expected over the lower, eastern elevations today. Surface winds in the 15 to 20 mph range are possible as the front passes through before it stalls out over the Palmer Ridge area. There is very little moisture return with this front, as shown by dew points increasing from ~25F to 35F. However, that will increase relative humidity values enough that critical fire weather conditions are not forecast. The lack of moisture return also means another day with precipitation chances close to zero. The northerly surface flow behind the front has transported smoke south over the Front Range and I-25 Corridor, so lower air quality is expected. With clear skies and ample sunshine, there is no flood threat issued.

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

Breezy conditions are expected over the plains this morning and today as another cold front passes through. The front is rather shallow, so high temperatures will only be affected over the lower elevations to about the Palmer Ridge. Highs will be in the mid 70Fs to lower 80Fs, and temperatures over the eastern mountains will reach the mid 60Fs (north) and lower 70Fs (south). It will be too dry for any rainfall or clouds to develop with the upslope flow, so no flooding is forecast. Although skies will be clear, smoke from the fires will travel southwards and lower air quality. Ash is being reported across the I-25 corridor this morning.

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

Above average temperatures are forecast along with clear skies. High temperatures are forecast to reach 4F to 8F above normal. So, highs will reach into the 80Fs over the lower elevations with 70Fs for most of the mountain valleys. No rainfall is forecast with PW measured at 0.25 inches in the Grand Junction sounding this morning, which is a new daily record low value.