Flash Flood Prediction Program

Time: 652 PM Wed May 24, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL BE ALLOWED TO EXPIRE AT 8:00 PM Message 1’s will be allowed to expire at 8:00pm as the threat for heavy rainfall has ended. Cooler temperatures behind the initial wave of thunderstorms has lowered temperatures in to the 60’s and the atmosphere has stabilized. There are a few lingering rain showers lurking to the W of the District that may pass through this evening but most areas will trend on the drier side from this point forward into the evening. Best chances for an additional light rain shower will be W of I-25 in or near the foothills. Dry conditions are expected all areas by around 10:00pm. There is some great news though as the SW flow aloft behind the upper level disturbance has helped to scour out much of the smoke/haze and air quality has improved significantly from earlier today and this trend of better air quality will continue into tomorrow. Lingering moisture and another upper level disturbance will result in afternoon thunderstorms on Thursday afternoon and the stronger storms will be capable of producing heavy rainfall which may result in another Message 1 day across the District if surface moisture remains elevated. Should surface moisture decrease Message 1's will be less likely tomorrow. STORM RAINFALL POTENTIAL AND DURATION: Any additional isolated rain showers will only produce a trace to 0.10” of rainfall in areas that receive shower activity. Most areas will be dry from this point forward. WORST CASE SCENARIO: Should a weak thunderstorm be able to develop rainfall rates of 0.1-0.3" in 10-30 minutes will be possible. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 1200 PM TO 800 PM 100 PM TO 700 PM Jefferson County 1 1200 PM TO 800 PM 100 PM TO 700 PM Broomfield County 1 1200 PM TO 800 PM 100 PM TO 700 PM Douglas County 1 1200 PM TO 800 PM 100 PM TO 700 PM Adams County 1 1200 PM TO 800 PM 100 PM TO 700 PM Denver County 1 1200 PM TO 800 PM 100 PM TO 700 PM DIA 1 1200 PM TO 800 PM 100 PM TO 700 PM Arapahoe County 1 1200 PM TO 800 PM 100 PM TO 700 PM the City of Aurora 1 1200 PM TO 800 PM 100 PM TO 700 PM Arvada 1 1200 PM TO 800 PM 100 PM TO 700 PM Wheat Ridge 1 1200 PM TO 800 PM 100 PM TO 700 PM Lakewood 1 1200 PM TO 800 PM 100 PM TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1000 PM WED Trace (25%) to 0.05" (15%) to 0.1" (5%) ISSUED Arapahoe Current TO 1000 PM WED Trace (25%) to 0.05" (15%) to 0.1" (5%) ISSUED Boulder Current TO 1000 PM WED Trace (40%) to 0.05" (20%) to 0.1" (10%) ISSUED Broomfield Current TO 1000 PM WED Trace (30%) to 0.05" (20%) to 0.1" (5%) ISSUED Denver Current TO 1000 PM WED Trace (25%) to 0.05" (15%) to 0.1" (5%) ISSUED Douglas Current TO 1000 PM WED Trace (25%) to 0.05" (15%) to 0.1" (5%) ISSUED Jefferson Current TO 1000 PM WED Trace (40%) to 0.05" (20%) to 0.1" (10%) ISSUED Foothills above 6500ft       Boulder Current TO 1000 PM WED Trace (60%) to 0.05" (30%) to 0.1" (15%) ISSUED Douglas Current TO 1000 PM WED Trace (30%) to 0.05" (20%) to 0.1" (10%) ISSUED Jefferson Current TO 1000 PM WED Trace (60%) to 0.05" (30%) to 0.1" (15%) 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]