Time: 1205 PM Mon September 21, 2020 Forecaster: Justin Brooks

Heavy Precipitation Outlook
Flash Flood Prediction Program

WARM TODAY WITH A VERY SLIGHT CHANCE FOR A HIGH BASED AFTERNOON RAIN/ISOLATED THUNDERSTORM (FIX MSG POTENTIAL)
-Not much change in the overall pattern as Westerly upper-level flow continues to dominate over the region today. Another very slight chance for a high-based shower or weak thunderstorm this afternoon and early evening. Surface moisture remains minimal which will keep most areas on the dry side with any showers and weak thunderstorms favoring the higher terrain along the foothills and Palmer Divide. Best chances for storm activity today will be between 2pm and 8pm.
-Temperatures will continue to be above average with highs in the low to mid 80's along the plains with mid to upper 70's along the foothills. The smoke/haze is expected to continue to be lighter today around the Denver area, with smoke/haze increasing towards the Wyoming border. Mostly sunny skies early with clouds increasing this afternoon before clearing out this evening.
-Overnight dry conditions are expected as lows drop into the mid to upper 50's on the plains with upper 40's to low 50's along the foothills.
STORM RAINFALL POTENTIAL AND DURATION: Isolated high-based rain showers and possibly a weak thunderstorm will have the potential to produce a trace to 0.1". Supplemental QPF is available at https://qpf.udfcd.org

A LOOK AHEAD: A small uptick in moisture and a stronger disturbance will move through the region Tuesday resulting in a better chance for afternoon and early evening rain/isolated thunderstorms. High-pressure starts to build Wednesday resulting in dry conditions through the rest of the week with high temperatures jumping back into the upper 80's Thursday and Friday.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 200 PM TO 800 PM
Trace (20%) to 0.1" (10%) NONE
Arapahoe 200 PM TO 800 PM
Trace (20%) to 0.1" (10%) NONE
Boulder 200 PM TO 800 PM
Trace (20%) to 0.1" (10%) NONE
Broomfield 200 PM TO 800 PM
Trace (20%) to 0.1" (10%) NONE
Denver 200 PM TO 800 PM
Trace (20%) to 0.1" (10%) NONE
Douglas 200 PM TO 800 PM
Trace (20%) to 0.1" (15%) NONE
Jefferson 200 PM TO 800 PM
Trace (20%) to 0.1" (10%) NONE
Foothills above 6500ft      
Boulder 200 PM TO 800 PM
Trace (20%) to 0.1" (15%) NONE
Douglas 200 PM TO 800 PM
Trace (20%) to 0.1" (15%) NONE
Jefferson 200 PM TO 800 PM
Trace (20%) to 0.1" (15%) NONE
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.