Time: 139 AM Thu June 22, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S HAVE BEEN EXTENDED AND MESSAGE 2'S CONTINUE VALID FOR THE DISTRICT Message 1’s have been extended until 6am as the threat of heavy rainfall remains across the District. Message 2’s will continue valid until 6am as well. Persistent storm development continues at this time. These storms will likely continue over the next several hours with isolated rain showers possible through daybreak. Storms have weakened quite a bit from the afternoon and evening severe storms. However, elevated surface moisture with dew points still in the 50’s, combined with continued upper-level support, storms will continue to impact several areas over the District. These storms still contain moderate to heavy rainfall, with some stronger storms just off the perimeter of the District, which can create additional gust fronts through the overnight resulting in a chance for additional strong storm development within the District. Heavy rainfall from thunderstorms will easily produce excessive runoff roadways and may result in flash flooding within the District. Due to snow melt and recent rains many creeks and streams are already running relatively high and additional rainfall will exacerbate flows as the day progresses. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce 0.1-0.4" of rain. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.4-1.2" in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 2.4" of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 600 AM Current TO 500 AM Jefferson County 1 Current TO 600 AM Current TO 500 AM Broomfield County 1 Current TO 600 AM Current TO 500 AM Douglas County 2 Current TO 600 AM Current TO 500 AM Adams County 1 Current TO 600 AM Current TO 500 AM Denver County 1 Current TO 600 AM Current TO 500 AM DIA 1 Current TO 600 AM Current TO 500 AM Arapahoe County 1 Current TO 600 AM Current TO 500 AM the City of Aurora 1 Current TO 600 AM Current TO 500 AM Arvada 1 Current TO 600 AM Current TO 500 AM Wheat Ridge 1 Current TO 600 AM Current TO 500 AM Lakewood 1 Current TO 600 AM Current TO 500 AM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Arapahoe Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Boulder Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Broomfield Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Denver Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Douglas Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Jefferson Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Douglas Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (20%) ISSUED Jefferson Current TO 600 AM THU 0.1" (80%) to 0.4" (40%) to 1.2" (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]