Flash Flood Prediction Program

Time: 754 PM Sat May 22, 2021 Forecaster: Justin Brooks ------------------------- 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 come to an end. Strong to severe storms have moved well out onto the eastern plains this evening with cloudy and cool temperatures heading into the evening. - A few additional scattered showers/isolated thunderstorms could be possible this evening and through the overnight into Sunday morning. Any rain shower activity will typically produce a trace to 0.2" in 10-30 minutes, although a moderate rain shower or thunderstorm could have the potential to produce 0.2-0.4" of rainfall in that same timeframe. Storm motions will continue to be relatively brisk between 10-20mph from S/SW to N/NE helping limit any point rainfall amounts. - Cloudy skies will persist through the evening with overnight lows dropping into the upper 40's to low 50's on the plains with upper 30's to low 40's along the foothills. With excess surface moisture in place, expect a few areas of patchy fog tomorrow morning with partly sunny skies into the later morning hours. Temperatures tomorrow will reach the 70's to around 80, breezy, with another chance for afternoon rain showers/isolated thunderstorms. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will produce a trace to 0.2" in 10-30min. A weak to moderate rain shower/thunderstorm could produce 0.2-0.4" in 10-30 minutes. WORST CASE SCENARIO: A slower moving thunderstorm or training of thunderstorms could produce 0.8" in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 800 PM Current TO 800 PM Jefferson County 1 Current TO 800 PM Current TO 800 PM Broomfield County 1 Current TO 800 PM Current TO 800 PM Douglas County 1 Current TO 800 PM Current TO 800 PM Adams County 1 Current TO 800 PM Current TO 800 PM Denver County 1 Current TO 800 PM Current TO 800 PM DIA 1 Current TO 800 PM Current TO 800 PM Arapahoe County 1 Current TO 800 PM Current TO 800 PM the City of Aurora 1 Current TO 800 PM Current TO 800 PM Arvada 1 Current TO 800 PM Current TO 800 PM Wheat Ridge 1 Current TO 800 PM Current TO 800 PM Lakewood 1 Current TO 800 PM Current TO 800 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Arapahoe Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Boulder Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Broomfield Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Denver Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Douglas Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Jefferson Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (5%) ISSUED Foothills above 6500ft       Boulder Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (10%) ISSUED Douglas Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (10%) ISSUED Jefferson Current TO 700 AM SUN Trace (50%) to 0.2" (25%) to 0.4" (10%) 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]