Flash Flood Prediction Program

Time: 1016 AM Sun May 2, 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 are currently valid until 8:00pm this evening. - Shower and thunderstorm activity is already blossoming over W/NW Boulder County and will fill in over the District through noon. 2-3 rounds of showers and thunderstorms are likely into the evening with stronger storms capable of producing brief heavy rainfall that may lead to excessive runoff. Relatively fast storm motions from SW to NE at 20-25mph will help to keep heavier rainfall brief with training of thunderstorm cells having the greatest threat for a prolonged period of heavy rainfall. - Strong thunderstorms may also become severe, producing large hail/accumulating hail, gusty winds and frequent cloud-to-ground lightning. Thunderstorm activity is expected to diminish as temperatures cool this evening with a widespread rain forecast to fill in with lighter rainfall rates overnight into Monday morning. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: Training of moderate/strong thunderstorm cells may result in up to 1.6" of rain in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Broomfield County 1 Current TO 800 PM 1100 AM TO 700 PM Jefferson County 1 Current TO 800 PM 1100 AM TO 700 PM Boulder County 1 Current TO 800 PM 1100 AM TO 700 PM Douglas County 1 Current TO 800 PM 1100 AM TO 700 PM Adams County 1 Current TO 800 PM 1100 AM TO 700 PM Denver County 1 Current TO 800 PM 1100 AM TO 700 PM DIA 1 Current TO 800 PM 1100 AM TO 700 PM Arapahoe County 1 Current TO 800 PM 1100 AM TO 700 PM the City of Aurora 1 Current TO 800 PM 1100 AM TO 700 PM Arvada 1 Current TO 800 PM 1100 AM TO 700 PM Wheat Ridge 1 Current TO 800 PM 1100 AM TO 700 PM Lakewood 1 Current TO 800 PM 1100 AM TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Arapahoe 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Broomfield 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Denver 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Douglas 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Jefferson 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Boulder Current TO 800 PM SUN 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Foothills above 6500ft       Douglas 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED Jefferson 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED Boulder Current TO 800 PM SUN 0.1" (100%) to 0.3" (80%) 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]