Flash Flood Prediction Program

Time: 351 PM Sun August 27, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1’S HAVE BEEN ISSUED EFFECTIVE UNTIL 9:00 PM Message 1’s have been issued effective until 9pm as there is a threat of heavy rainfall this afternoon and evening. A few storms have formed along the foothills at this time and are slowly moving onto the plains. Generally, storms have mixed out as they move off the foothills, however, a better chance for storms to remain moderate to strong as we move into the late afternoon and evening. Storm motions should be west to east between 5-10mph, with some erratic storm motions possible. Especially due to gusts fronts that will likely move into the District over the next couple of hours. The largest threat for storms today will be a quick 0.30-0.75” in 10-30 minutes, with a very low threat for any rainfall over an inch as most storms pulse up and down relatively quickly. Showers and thunderstorm chances will last through sunset, with a few lingering showers/isolated thunderstorms possible through the overnight, although the threat for heavy rainfall should diminish between 8-9pm. STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms will produce rainfall of 0.10 to 0.30” total in 10-30 minutes. Strong storms have the potential to produce heavy rainfall of 0.30 to 0.75” total in 10-30 minutes. WORST CASE SCENARIO: Strong stationery, or training of thunderstorms has the potential to produce 0.75” to 1.25” in under 60 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 SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Arapahoe Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Boulder Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Broomfield Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Denver Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Douglas Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Jefferson Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Douglas Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (20%) ISSUED Jefferson Current TO 900 PM SUN 0.05" (80%) to 0.3" (40%) to 0.75" (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]