Flash Flood Prediction Program

Time: 1251 PM Mon August 22, 2022 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR PORTIONS OF THE DISTRICT - Message 1's have been issued for Adams, Arapahoe, Denver, Douglas and Jefferson Counties and will be valid until 8:30 PM. - A surface wind convergence line is currently draped across portions of Adams, Arapahoe and Douglas Counties. This is an area that may initiate thunderstorms later this afternoon. Should storms develop they will be stationary or move very little and stronger storms will be capable of producing heavy rainfall that could lead to excessive runoff. Should the risk increase for heavy rainfall over Boulder and Broomfield Counties, Message 1's may be issued later this afternoon. - Best chances for storms overall looks to be E of I-25 and S of I-70 with prime time between 2:00 PM and 7:30 PM. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. Moderate to strong thunderstorms will be capable of producing heavy rainfall rates of 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm will have the potential to produce up to 1.6" of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Lakewood 1 100 PM TO 830 PM 200 PM TO 730 PM Arvada 1 100 PM TO 830 PM 200 PM TO 730 PM Wheat Ridge 1 100 PM TO 830 PM 200 PM TO 730 PM the City of Aurora 1 100 PM TO 830 PM 200 PM TO 730 PM Arapahoe County 1 100 PM TO 830 PM 200 PM TO 730 PM DIA 1 100 PM TO 830 PM 200 PM TO 730 PM Denver County 1 100 PM TO 830 PM 200 PM TO 730 PM Douglas County 1 100 PM TO 830 PM 200 PM TO 730 PM Adams County 1 100 PM TO 830 PM 200 PM TO 730 PM Jefferson County 1 100 PM TO 830 PM 200 PM TO 730 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 830 PM 0.1" (60%) to 0.3" (30%) to 0.9" (15%) ISSUED Arapahoe 100 PM TO 830 PM 0.1" (75%) to 0.3" (40%) to 0.9" (20%) ISSUED Boulder 100 PM TO 830 PM 0.1" (40%) to 0.3" (20%) to 0.9" (10%) LOW Broomfield 100 PM TO 830 PM 0.1" (40%) to 0.3" (20%) to 0.9" (10%) LOW Denver 100 PM TO 830 PM 0.1" (75%) to 0.3" (40%) to 0.9" (20%) ISSUED Douglas 100 PM TO 830 PM 0.1" (80%) to 0.3" (50%) to 0.9" (30%) ISSUED Jefferson 100 PM TO 830 PM 0.1" (75%) to 0.3" (40%) to 0.9" (20%) ISSUED Foothills above 6500ft       Boulder 100 PM TO 830 PM 0.1" (50%) to 0.3" (25%) to 0.9" (10%) LOW Douglas 100 PM TO 830 PM 0.1" (80%) to 0.3" (50%) to 0.9" (30%) ISSUED Jefferson 100 PM TO 830 PM 0.1" (75%) to 0.3" (40%) 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]