Time: 930 AM Sun August 11, 2024 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- Morning drizzle, clearing before afternoon showers and thunderstorms Synoptic-scale lift is driving formation of some very weak showers in and around the District this morning, with a few gauges in the foothills picking up traces of precipitation. These showers will clear by late morning, giving way to clear skies that will heat the District to around 90, and initiate convection in the high country north and west of the District in the early afternoon. Storms will make their way off the foothills in the midafternoon, and will have seasonably normal levels of moisture to work with once they do. This will lead to some storms causing brief heavy rainfall, small hail, and gusty outflow winds. Similar to yesterday, storms will move quickly, so concerns for message issuance will favor the potential for 0.50" in 10 minutes rather than over 1.00" within an hour. However, similar to yesterday, if a complex of thunderstorms develops, or training of moderate to strong thunderstorm cells, 1.00-1.50” will be possible for the worst case scenario in up to 60 minutes. Skies will clear as the evening turns to night, and overnight lows will return to the upper 50s on the plains with low to mid 50s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers and thunderstorms will produce 0.10"-0.25" total in 10-30 minutes. A stronger or slower-moving thunderstorm will produce up to 0.25"-0.75" total in 10-30 minutes. WORST CASE SCENARIO: An anchored/stationary thunderstorm, thunderstorm complex, or training of thunderstorms along a boundary, may be capable of producing 1.00-1.50" of rainfall in up to 60 minutes. A LOOK AHEAD: Likely moderate message issuance potential tomorrow as an approaching cold front will provide necessary lift for scattered to numerous showers and thunderstorms tomorrow afternoon. Typical afternoon and evening showers/thunderstorms will continue through the work week but slowly taper off each day, with dry conditions expected by Friday! LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Arapahoe 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Boulder 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Broomfield 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Denver 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Douglas 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Jefferson 200 PM TO 800 PM 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Foothills above 6500ft       Boulder 100 PM TO 800 PM 0.1" (60%) to 0.3" (40%) to 0.8" (10%) LOW Douglas 100 PM TO 800 PM 0.1" (60%) to 0.3" (40%) to 0.8" (10%) LOW Jefferson 100 PM TO 800 PM 0.1" (60%) to 0.3" (40%) to 0.8" (10%) LOW MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]