Time: 1148 AM Thu August 26, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT - Message 1's have been issued for the entire District and will be valid until 10pm this evening. An upper level disturbance will move through this afternoon and is expected to produce isolated to widely scattered showers and thunderstorms into the evening. Strong thunderstorms will be capable of producing brief heavy rainfall. - Showers and thunderstorms will move from SW to NE at around 20mph helping to limit point rainfall amounts from a single storm. Outflow boundaries from storms outside the District may help to anchor or slow down a stronger storm resulting in an extended period of heavy rainfall which may lead to excessive runoff. - Best chances for thunderstorm activity will be through 9 or 10pm this evening. Beyond 10pm additional rain showers and weaker thunderstorms remain possible until about midnight. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3" of rain. Moderate to strong thunderstorms will have the potential to produce 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: Moisture levels remain higher than anticipated resulting in moderate to strong thunderstorms with the potential to produce heavy rainfall of 0.5-1.5" in 10-30 minutes and up to 2.5" in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Broomfield County 1 Current TO 1000 PM 100 PM TO 900 PM Jefferson County 1 Current TO 1000 PM 100 PM TO 900 PM Boulder County 1 Current TO 1000 PM 100 PM TO 900 PM Douglas County 1 Current TO 1000 PM 100 PM TO 900 PM Adams County 1 Current TO 1000 PM 100 PM TO 900 PM Denver County 1 Current TO 1000 PM 100 PM TO 900 PM DIA 1 Current TO 1000 PM 100 PM TO 900 PM Arapahoe County 1 Current TO 1000 PM 100 PM TO 900 PM the City of Aurora 1 Current TO 1000 PM 100 PM TO 900 PM Arvada 1 Current TO 1000 PM 100 PM TO 900 PM Wheat Ridge 1 Current TO 1000 PM 100 PM TO 900 PM Lakewood 1 Current TO 1000 PM 100 PM TO 900 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 1200 PM TO 1000 PM 0.1" (75%) to 0.3" (50%) to 0.9" (25%) ISSUED Arapahoe 1200 PM TO 1000 PM 0.1" (75%) to 0.3" (50%) to 0.9" (25%) ISSUED Boulder 1200 PM TO 1000 PM 0.1" (80%) to 0.3" (50%) to 0.9" (20%) ISSUED Broomfield 1200 PM TO 1000 PM 0.1" (80%) to 0.3" (50%) to 0.9" (20%) ISSUED Denver 1200 PM TO 1000 PM 0.1" (75%) to 0.3" (50%) to 0.9" (25%) ISSUED Douglas 1200 PM TO 1000 PM 0.1" (80%) to 0.3" (50%) to 0.9" (20%) ISSUED Jefferson 1200 PM TO 1000 PM 0.1" (80%) to 0.3" (50%) to 0.9" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 1000 PM THU 0.1" (90%) to 0.3" (60%) to 0.9" (20%) ISSUED Douglas Current TO 1000 PM THU 0.1" (90%) to 0.3" (60%) to 0.9" (20%) ISSUED Jefferson Current TO 1000 PM THU 0.1" (90%) to 0.3" (60%) to 0.9" (20%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]