Flash Flood Prediction Program

Time: 132 AM Sat July 31, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2'S CONTINUE VALID INTO SATURDAY - Message 2's continue valid until 9pm Saturday. The Message 3's issued earlier for SE Boulder and Broomfield Counties have been allowed to expire at 1:30am. - Thunderstorm activity diminished hours ago and light rain showers continue, mainly impacting northern areas of the District currently. Rain showers are expected to continue to slowly decrease as the overnight wears on with a generally dry period into late morning Saturday. - By 10am Saturday there will already be a chance for thunderstorms over the District with prime time from around noon to 6pm. Thunderstorms that develop on Saturday will be very capable of producing heavy rainfall. With the recent moisture it may not take as much rain on Saturday to produce excessive runoff and possibly flash flooding. STORM RAINFALL POTENTIAL AND DURATION: Rain showers will produce a trace to 0.3" in 60 minutes or less through daybreak Saturday. WORST CASE SCENARIO: A weak to moderate thunderstorm is able to develop overnight with the potential to produce 0.3-0.9" of heavy rain in 10-30 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 900 PM 1200 PM TO 600 PM Jefferson County 1 Current TO 900 PM 1200 PM TO 600 PM Broomfield County 1 Current TO 900 PM 1200 PM TO 600 PM Douglas County 1 Current TO 900 PM 1200 PM TO 600 PM Adams County 1 Current TO 900 PM 1200 PM TO 600 PM Denver County 1 Current TO 900 PM 1200 PM TO 600 PM DIA 1 Current TO 900 PM 1200 PM TO 600 PM Arapahoe County 1 Current TO 900 PM 1200 PM TO 600 PM the City of Aurora 1 Current TO 900 PM 1200 PM TO 600 PM Arvada 1 Current TO 900 PM 1200 PM TO 600 PM Wheat Ridge 1 Current TO 900 PM 1200 PM TO 600 PM Lakewood 1 Current TO 900 PM 1200 PM TO 600 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 60-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1000 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (30%) ISSUED Arapahoe Current TO 1000 AM SAT Trace (60%) to 0.1" (30%) to 0.3" (10%) ISSUED Boulder Current TO 1000 AM SAT Trace (100%) to 0.1" (75%) to 0.3" (30%) ISSUED Broomfield Current TO 1000 AM SAT Trace (100%) to 0.1" (75%) to 0.3" (30%) ISSUED Denver Current TO 1000 AM SAT Trace (60%) to 0.1" (30%) to 0.3" (10%) ISSUED Douglas Current TO 1000 AM SAT Trace (60%) to 0.1" (30%) to 0.3" (10%) ISSUED Jefferson Current TO 1000 AM SAT Trace (60%) to 0.1" (30%) to 0.3" (10%) ISSUED Foothills above 6500ft       Boulder Current TO 1000 AM SAT Trace (100%) to 0.1" (45%) to 0.3" (30%) ISSUED Douglas Current TO 1000 AM SAT Trace (60%) to 0.1" (30%) to 0.3" (10%) ISSUED Jefferson Current TO 1000 AM SAT Trace (80%) to 0.1" (50%) to 0.3" (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]