Flash Flood Prediction Program

Time: 448 PM Fri July 8, 2022 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT VALID UNTIL 9:30 PM - Message 1's have been issued and will be valid for the entire District until 9:30 PM. - Thunderstorm development outside the District to the N and S/SE has produced multiple outflow boundaries which will move through the District and may act as triggers for new thunderstorms over the coming hours. Slow moving or stationary thunderstorm that develop along these surface wind convergence boundaries may move very slowly or remain stationary producing the potential for heavy rainfall. Strong thunderstorms may also contain gusty winds, hail and frequent cloud-to-ground lightning. - Thunderstorms are currently erupting over NW Jefferson County and portions of Arapahoe County with new storms expected to fill in over other areas of the District shortly. Prime time for thunderstorm activity is through 8:30 PM. Upper level winds will carry individual storms from NW to SE at around 15mph. Slow moving or briefly anchored storms will produce the greatest threat for extended periods of heavy rainfall that may lead to excessive runoff and possibly flash flooding. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.4" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.4-1.2" in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 2.0" of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 930 PM 530 PM TO 830 PM Jefferson County 1 Current TO 930 PM 500 PM TO 830 PM Broomfield County 1 Current TO 930 PM 530 PM TO 830 PM Douglas County 1 Current TO 930 PM 530 PM TO 830 PM Adams County 1 Current TO 930 PM 530 PM TO 830 PM Denver County 1 Current TO 930 PM 530 PM TO 830 PM DIA 1 Current TO 930 PM 530 PM TO 830 PM Arapahoe County 1 Current TO 930 PM 500 PM TO 830 PM the City of Aurora 1 Current TO 930 PM 530 PM TO 830 PM Arvada 1 Current TO 930 PM 530 PM TO 830 PM Wheat Ridge 1 Current TO 930 PM 530 PM TO 830 PM Lakewood 1 Current TO 930 PM 530 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM FRI 0.1" (75%) to 0.4" (50%) to 1.0" (15%) ISSUED Arapahoe Current TO 900 PM FRI 0.1" (90%) to 0.4" (60%) to 1.0" (30%) ISSUED Boulder Current TO 900 PM FRI 0.1" (80%) to 0.4" (50%) to 1.0" (20%) ISSUED Broomfield Current TO 900 PM FRI 0.1" (75%) to 0.4" (50%) to 1.0" (15%) ISSUED Denver Current TO 900 PM FRI 0.1" (75%) to 0.4" (50%) to 1.0" (15%) ISSUED Douglas Current TO 900 PM FRI 0.1" (75%) to 0.4" (50%) to 1.0" (15%) ISSUED Jefferson Current TO 900 PM FRI 0.1" (90%) to 0.4" (60%) to 1.0" (30%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM FRI 0.1" (85%) to 0.4" (50%) to 1.0" (20%) ISSUED Douglas Current TO 900 PM FRI 0.1" (85%) to 0.4" (50%) to 1.0" (20%) ISSUED Jefferson Current TO 900 PM FRI 0.1" (85%) to 0.4" (50%) to 1.0" (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]