Time: 408 PM Thu June 1, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL CONTINUE VALID Message 1’s will continue valid until 9pm this evening. The first round of moderate to strong thunderstorms is currently exiting the District to the east with additional showers and thunderstorms expected to develop over the next few hours. Moderate to strong thunderstorms will still be capable of producing brief heavy rainfall that may lead to excessive runoff. Stronger thunderstorms may also produce hail. Storm motions are relatively slow from SW to NE at 10-15mph. The slow storm motions will allow for extended periods of moderate to heavy rain under thunderstorms. Best chances for additional storms will be through 8-9pm then drier conditions are expected to develop for the later evening and overnight period. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 1.6” of rain in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 1200 PM TO 900 PM 100 PM TO 830 PM Jefferson County 1 1200 PM TO 900 PM 100 PM TO 830 PM Broomfield County 1 1200 PM TO 900 PM 100 PM TO 830 PM Douglas County 1 1200 PM TO 900 PM 100 PM TO 830 PM Adams County 1 1200 PM TO 900 PM 100 PM TO 830 PM Denver County 1 1200 PM TO 900 PM 100 PM TO 830 PM DIA 1 1200 PM TO 900 PM 100 PM TO 830 PM Arapahoe County 1 1200 PM TO 900 PM 100 PM TO 830 PM the City of Aurora 1 1200 PM TO 900 PM 100 PM TO 830 PM Arvada 1 1200 PM TO 900 PM 100 PM TO 830 PM Wheat Ridge 1 1200 PM TO 900 PM 100 PM TO 830 PM Lakewood 1 1200 PM TO 900 PM 100 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Arapahoe Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Boulder Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Broomfield Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Denver Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Douglas Current TO 900 PM THU 0.1" (80%) to 0.3" (60%) to 0.8" (20%) ISSUED Jefferson Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Douglas Current TO 900 PM THU 0.1" (80%) to 0.3" (60%) to 0.8" (20%) ISSUED Jefferson Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) 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]