Time: 819 AM Tue September 22, 2020 Forecaster: Justin Brooks

Heavy Precipitation Outlook
Flash Flood Prediction Program

WARM TODAY WITH ANOTHER CHANCE FOR SCATTERED HIGH-BASED RAIN/ISOLATED THUNDERSTORMS THIS AFTERNOON & EARLY EVE
-Today is officially the first day of Fall, although the current pattern across the region will feel more like extended summer! Temperatures today will remain in the low to mid 80's across the plains with mid to upper 70's along the foothills.
-Partly cloudy skies currently as clouds increase into the afternoon. Rain/isolated thunderstorms will initiate over the high country around midday today and will begin to move across the District between 1-3pm with additional weaker rounds of showers possible into the evening. Best chance for precipitation will remain along the foothills and Palmer Divide this afternoon as dry conditions aloft will limit the amount of precipitation making it to the ground east of the foothills. Isolated rain/thunderstorm chances will continue through sunset before chances taper off after 8pm this evening before skies gradually clear into the overnight.
-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

WORST CASE SCENARIO: A moderate thunderstorm has the potential to produce 0.1-0.3" of rain in 30-45min.

A LOOK AHEAD: High-pressure starts to build Wednesday leading to dry conditions through the rest of the week. Temperatures will remain above average with highs in the low to upper 80's Wednesday and Thursday with around 90 degrees possible on Friday.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Arapahoe 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Boulder 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Broomfield 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Denver 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Douglas 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Jefferson 200 PM TO 900 PM
Trace (50%) to 0.1" (20%) to 0.3" (5%) NONE
Foothills above 6500ft      
Boulder 100 PM TO 800 PM
Trace (60%) to 0.1" (30%) to 0.3" (10%) NONE
Douglas 100 PM TO 800 PM
Trace (60%) to 0.1" (40%) to 0.3" (15%) NONE
Jefferson 100 PM TO 800 PM
Trace (60%) to 0.1" (30%) to 0.3" (10%) NONE
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.