FTB 09-30-2015: FTB Season Ending with Unsettled Weather

Issue Date: 9/30/2015
Issue Time: 9:03 AM

**THIS IS THE FINAL FTB OF 2015. THANK YOU ALL FOR READING, AND WE LOOK FORWARD TO ANOTHER SUCCESSFUL SEASON IN 2016.**

NO FLOOD THREAT IS FORECAST.

In a slightly poetic end to a drought-busting season, Mother Nature is sending the FTB into the offseason with isolated-to-scattered showers/thunderstorms. Apparent in the water vapor imagery below is the west-northwest flow aloft over Colorado, with good moisture and embedded disturbances earmarked for the state. The result will be another day of unsettled weather, but no flood threat is warranted.

WV_09302015

A general lack of instability across most of the state will keep rain rates well below flood threat thresholds. The only regions that will hold the threat of bouts with moderate-to-heavy rain will be the Raton Ridge and Southeast Plains regions, namely the counties of Las Animas, Baca, Bent, Prowers, and Otero Counties. In that corner of the state, a pocket of instability will coincide with favorable low-level moisture, weak surface convergence, and a slight upsloping wind across the Raton Mesa to produce isolated-to-widely scattered thunderstorms. A couple will become strong-to-severe, with the main threats being wind gusts of 40-60 mph, hail 0.75-1.5 inches in diameter, and brief periods with moderate-to-heavy rain. For more information on rain rates and timing, be sure and check out the zone-specific discussions below.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below (hover over threat areas for more details). For Zone-Specific forecasts, jump below the map.

Flood Threat Legend

Zone-Specific Forecasts

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

Isolated-to-scattered showers/weak thunderstorms are expected today, favoring the higher terrain. Steering winds will help push showers over adjacent valleys during the afternoon and evening hours. Rain rates will generally be low, with most showers producing less than 0.25 inches/hour. The exception will be over the San Juan Mountains, San Luis Valley, and Southeast Mountains, were maximum rain rates will be 0.4-0.75 inches/hour.

Timing: Currently, a few isolated showers are ongoing across the Northern Mountains, Northwest Slope, and Central Mountains regions. Overall, the timing of today’s activity will be 11 AM – 8 PM, with a few showers lingering until 10 PM.

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

Isolated showers/weak thunderstorms expected, with the best coverage over the Front Range, Southeast Mountains, and Palmer Ridge regions. Much of the Urban Corridor and Northeast Plains north of I-70 will be too stable today to support precipitation. Rain rates will be low, with most activity producing 0.15-0.3 inches/hour. Across the Palmer Ridge, a thunderstorm will hold the potential to produce 0.4-0.7 inches/hour rain rates.

Timing: Noon – 10 PM

Southeast Plains and Raton Ridge:

Isolated-to-widely scattered thunderstorms expected, with a couple becoming strong-to-severe. Damaging wind gusts (40-60 mph), hail (0.75-1.0 inches in diameter), and periods of moderate-to-heavy rain are the main threats. Maximum rain rates will be 1.2-1.6 inches/hour, but storm motions will mitigate the heavy rain threat to any one location.

Timing: 2 PM – 11 PM