Flash Flood Prediction Program

Time: 253 PM Sat June 19, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL CONTINUE VALID, ANOTHER ROUND OF THUNDERSTORMS POSSIBLE - Message 1's will continue valid until 8:00pm this evening as another round of thunderstorms is possible over the District and may contain heavy rainfall. - Behind the first round of thunderstorms that moved through the District there is a lull expected over the next couple hours with another round possible between 5-7pm. If temperatures recover back into the upper 80s over the coming hours this second round of storms may become strong with the potential for brief heavy rainfall. If temperatures do not recover well then additional thunderstorms this afternoon may trend on the weaker side. - Strong thunderstorms that develop today may also become severe with gusty winds in excess of 50mph and large hail of 1" or more in diameter being the primary threats. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A large, slower moving thunderstorm or training of thunderstorm cells will have the potential to produce up to 1.5" of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 1200 PM TO 800 PM 400 PM TO 700 PM Jefferson County 1 1200 PM TO 800 PM 400 PM TO 700 PM Broomfield County 1 1200 PM TO 800 PM 400 PM TO 700 PM Douglas County 1 1200 PM TO 800 PM 400 PM TO 700 PM Adams County 1 1200 PM TO 800 PM 400 PM TO 700 PM Denver County 1 1200 PM TO 800 PM 400 PM TO 700 PM DIA 1 1200 PM TO 800 PM 400 PM TO 700 PM Arapahoe County 1 1200 PM TO 800 PM 400 PM TO 700 PM the City of Aurora 1 1200 PM TO 800 PM 400 PM TO 700 PM Arvada 1 1200 PM TO 800 PM 400 PM TO 700 PM Wheat Ridge 1 1200 PM TO 800 PM 400 PM TO 700 PM Lakewood 1 1200 PM TO 800 PM 400 PM TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Arapahoe 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Boulder 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Broomfield 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Denver 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Douglas 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Jefferson 400 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Foothills above 6500ft       Boulder 400 PM TO 800 PM 0.1" (80%) to 0.3" (40%) to 0.8" (15%) ISSUED Douglas 400 PM TO 800 PM 0.1" (80%) to 0.3" (40%) to 0.8" (15%) ISSUED Jefferson 400 PM TO 800 PM 0.1" (80%) to 0.3" (40%) 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]