Time: 1040 AM Sat June 26, 2021 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- HEAVY RAINFALL SHOWERS AND THUNDERSTORMS TODAY AND INTO THIS EVENING - A cold front is moving into the region form the north this morning with rain showers and weak thunderstorms forming along the front at this time. Currently dew points are in the low 50's in the District, combined with sufficient mid to upper-level moisture will bring a good chance for heavy rainfall, even out of weak to moderate rain showers. moderate to strong thunderstorms will be very capable of producing heavy rainfall that may lead to excessive runoff and possibly flash flooding. - Individual thunderstorms will be relatively fast moving from N/NW to S/SE at 10-20mph helping limit point rainfall amounts from a single storm. Outflow boundaries from thunderstorms this afternoon may be a focus for stronger storms with the potential to produce extended periods of heavy rainfall. Training of thunderstorm cells could also be a culprit for linger duration heavy rainfall especially areas along the foothills. Prime time for thunderstorms is from roughly 11am to 9pm with a slight chance for lingering showers after 9pm. - After 10pm, skies will gradually clear through the overnight with low dropping into the upper 50's to low 60's on the plains with low to mid 50's for the foothills. STORM RAINFALL POTENTIAL AND DURATION: Moderate to strong thunderstorms will have the potential to produce 0.3-0.9" 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 1.8" in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Lakewood 1 Current TO 900 PM 1100 AM TO 800 PM the City of Aurora 1 Current TO 900 PM 1100 AM TO 800 PM Arvada 1 Current TO 900 PM 1100 AM TO 800 PM Wheat Ridge 1 Current TO 900 PM 1100 AM TO 800 PM DIA 1 Current TO 900 PM 1100 AM TO 800 PM Arapahoe County 1 Current TO 900 PM 1100 AM TO 800 PM Denver County 1 Current TO 900 PM 1100 AM TO 800 PM Adams County 1 Current TO 900 PM 1100 AM TO 800 PM Douglas County 1 Current TO 900 PM 1100 AM TO 800 PM Jefferson County 1 Current TO 900 PM 1100 AM TO 800 PM Broomfield County 1 Current TO 900 PM 1100 AM TO 800 PM Boulder County 1 Current TO 900 PM 1100 AM 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" (45%) to 0.9" (20%) ISSUED Arapahoe Current TO 900 PM SAT 0.1" (90%) to 0.3" (45%) to 0.9" (20%) ISSUED Boulder Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.9" (25%) ISSUED Broomfield Current TO 900 PM SAT 0.1" (90%) to 0.3" (45%) to 0.9" (20%) ISSUED Denver Current TO 900 PM SAT 0.1" (90%) to 0.3" (45%) to 0.9" (20%) ISSUED Douglas Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.9" (25%) ISSUED Jefferson Current TO 900 PM SAT 0.1" (90%) to 0.3" (50%) to 0.9" (25%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM SAT 0.1" (90%) to 0.3" (60%) to 0.9" (30%) ISSUED Douglas Current TO 900 PM SAT 0.1" (90%) to 0.3" (60%) to 0.9" (30%) ISSUED Jefferson Current TO 900 PM SAT 0.1" (90%) to 0.3" (60%) to 0.9" (30%) 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]