Flash Flood Prediction Program

Time: 320 PM Mon August 5, 2024 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1’S HAVE BEEN ISSUED EFFECTIVE UNTIL 10:00 PM Storms have initiated along the foothills this afternoon and will likely move into the District over the next hour or so. Temperatures today have been cooler, however, dew points are elevated at the surface currently in the upper 40s to low 50s. Combined with model driven PWAT values between 1.00-1.25” will result in efficient rainfall producing storms this afternoon and evening. Storms will also be slow moving from west to east around 5mph, with anchored storms likely forming along outflow boundaries. These slow-moving storms will result in the potential for both 0.50” in 10-20 minutes and due to PWAT values above an inch, could result in an isolated 1.00-1.25” in under 60 minutes. A couple of rounds of storms will be possible this afternoon and evening, the first round, moving in between 4-6pm likely having more impact than the later round moving in between 7-9pm. Once these rounds move out, skies will gradually clear through the overnight with temperatures dropping into the mid 60s for the plains with around 60 degrees along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce 0.05-0.30" total in 10-30 minutes. A moderate to strong thunderstorm will produce rainfall rates of 0.30”-0.80” total in 10- 30 minutes. WORST CASE SCENARIO: A slow-moving thunderstorm, training of thunderstorms cells or a large thunderstorm complex may result in up to 1.25” of rain in 30-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 1000 PM Current TO 900 PM Jefferson County 1 Current TO 1000 PM Current TO 900 PM Broomfield County 1 Current TO 1000 PM Current TO 900 PM Douglas County 1 Current TO 1000 PM Current TO 900 PM Adams County 1 Current TO 1000 PM Current TO 900 PM Denver County 1 Current TO 1000 PM Current TO 900 PM DIA 1 Current TO 1000 PM Current TO 900 PM Arapahoe County 1 Current TO 1000 PM Current TO 900 PM the City of Aurora 1 Current TO 1000 PM Current TO 900 PM Arvada 1 Current TO 1000 PM Current TO 900 PM Wheat Ridge 1 Current TO 1000 PM Current TO 900 PM Lakewood 1 Current TO 1000 PM Current TO 900 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Arapahoe Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Boulder Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Broomfield Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Denver Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Douglas Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Jefferson Current TO 1000 PM MON 0.05" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Foothills above 6500ft       Boulder Current TO 1000 PM MON 0.05" (75%) to 0.3" (50%) to 0.8" (25%) ISSUED Douglas Current TO 1000 PM MON 0.05" (75%) to 0.3" (50%) to 0.8" (25%) ISSUED Jefferson Current TO 1000 PM MON 0.05" (75%) to 0.3" (50%) to 0.8" (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]