Flash Flood Prediction Program

Time: 337 PM Sat June 26, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S CONTINUE VALID FOR THE DISTRICT - Message 1's continue valid for the entire District although the threat for thunderstorms is lower as precipitation thus far is favoring moderate to briefly heavy non-thunderstorm rain showers with short lived weak thunderstorms. - With temperatures in the 50's over much of the District precipitation is favoring a general rain with the stronger thunderstorm activity limited to the higher terrain well W of the District and further E onto the plains. The current rain and isolated weak thunderstorms showers are producing rainfall rates of 0.2-0.4" in 10-30 minutes on the heavy end and is resulting in minor runoff. If a moderate or strong thunderstorm is able to develop it will be very capable of producing brief heavy rain that may lead to excessive runoff and flash flooding. - Shower and weak thunderstorm activity is expected to continue to come in waves into the evening with conditions drying out around sunset or shortly after. It may not take as much rain today to produce runoff as the ground is saturated in some areas and smaller creeks and streams may be running high into the evening. 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 0.3-0.8" 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 1.6" in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 900 PM Current TO 800 PM Jefferson County 1 Current TO 900 PM Current TO 800 PM Broomfield County 1 Current TO 900 PM Current TO 800 PM Douglas County 1 Current TO 900 PM Current TO 800 PM Adams County 1 Current TO 900 PM Current TO 800 PM Denver County 1 Current TO 900 PM Current TO 800 PM DIA 1 Current TO 900 PM Current TO 800 PM Arapahoe County 1 Current TO 900 PM Current TO 800 PM the City of Aurora 1 Current TO 900 PM Current TO 800 PM Arvada 1 Current TO 900 PM Current TO 800 PM Wheat Ridge 1 Current TO 900 PM Current TO 800 PM Lakewood 1 Current TO 900 PM Current TO 800 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Arapahoe Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Boulder Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Broomfield Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Denver Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Douglas Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Jefferson Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Douglas Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) ISSUED Jefferson Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.5" (10%) 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]