Flash Flood Prediction Program

Time: 508 PM Thu July 22, 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 will be valid until 10pm. - Thunderstorms are beginning to initiate over eastern areas of the District currently and are expected to become stronger and more numerous as the evening progresses. Storms will be slow moving with the potential to produce heavy rainfall that may lead to excessive runoff and possibly flash flooding. - Prime time for thunderstorms is from 6-9pm, likely favoring the plains versus the foothills. STORM RAINFALL POTENTIAL AND DURATION: Moderate to strong thunderstorms have the potential to produce 0.4-1.2" of heavy rain in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 2.2" in 60 minutes or less. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 1000 PM 600 PM TO 900 PM Jefferson County 1 Current TO 1000 PM 600 PM TO 900 PM Broomfield County 1 Current TO 1000 PM 600 PM TO 900 PM Douglas County 1 Current TO 1000 PM 600 PM TO 900 PM Adams County 1 Current TO 1000 PM 600 PM TO 900 PM Denver County 1 Current TO 1000 PM 600 PM TO 900 PM DIA 1 Current TO 1000 PM 600 PM TO 900 PM Arapahoe County 1 Current TO 1000 PM 600 PM TO 900 PM the City of Aurora 1 Current TO 1000 PM 600 PM TO 900 PM Arvada 1 Current TO 1000 PM 600 PM TO 900 PM Wheat Ridge 1 Current TO 1000 PM 600 PM TO 900 PM Lakewood 1 Current TO 1000 PM 600 PM TO 900 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1000 PM THU 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Arapahoe Current TO 1000 PM THU 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Boulder Current TO 1000 PM THU 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Broomfield Current TO 1000 PM THU 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Denver Current TO 1000 PM THU 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Douglas Current TO 1000 PM THU 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Jefferson Current TO 1000 PM THU 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Foothills above 6500ft       Boulder Current TO 1000 PM THU 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Douglas Current TO 1000 PM THU 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Jefferson Current TO 1000 PM THU 0.1" (75%) to 0.4" (50%) to 1.2" (25%) 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]