Flash Flood Prediction Program

Time: 226 PM Thu September 14, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1’S HAVE BEEN ISSUED EFFECTIVE UNTIL 9:00 PM A cold front will pass through the Front Range Urban Corridor keeping fall-like temperatures in place and will likely bring widespread rain showers and thunderstorms. Highs this afternoon will be stunted, only reaching the mid 70s for the plains with upper 60s to low 70s along the foothills. Showers and thunderstorms have initiated along the foothills and will increase in coverage over the next hour or so. Showers and thunderstorms become widespread between 4-6 PM. Chances of severe storms are very unlikely within the District as temperatures remain cool today, however, elevated available moisture will bring pockets of moderate to heavy rainfall which could potentially lead to some localized flooding under stronger storms. The peak timing for heavy rainfall will be between 4-8pm. Thunderstorm and heavy rainfall chances will likely dissipate by 8-9pm with widespread light to moderate showers dominating the area and continuing through the overnight. Overnight lows will dip into the low 50s for the plains with mid to upper 40s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce rainfall of a 0.10 to 0.50” total in 10-30 minutes. Moderate to strong showers have the potential to produce rainfall of 0.50 to 1.00” total in 10-30 minutes. WORST CASE SCENARIO: Strong stationery, or training of thunderstorms has the potential to produce 1.00” to 2.00” in under 60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 900 PM Current TO 830 PM Jefferson County 1 Current TO 900 PM Current TO 830 PM Broomfield County 1 Current TO 900 PM Current TO 830 PM Douglas County 1 Current TO 900 PM Current TO 830 PM Adams County 1 Current TO 900 PM Current TO 830 PM Denver County 1 Current TO 900 PM Current TO 830 PM DIA 1 Current TO 900 PM Current TO 830 PM Arapahoe County 1 Current TO 900 PM Current TO 830 PM the City of Aurora 1 Current TO 900 PM Current TO 830 PM Arvada 1 Current TO 900 PM Current TO 830 PM Wheat Ridge 1 Current TO 900 PM Current TO 830 PM Lakewood 1 Current TO 900 PM Current TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Arapahoe Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Boulder Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Broomfield Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Denver Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Douglas Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Jefferson Current TO 900 PM THU 0.1" (75%) to 0.5" (50%) to 1" (25%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM THU 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Douglas Current TO 900 PM THU 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Jefferson Current TO 900 PM THU 0.1" (90%) to 0.5" (60%) to 1" (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]