Time: 751 PM Sun May 2, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL BE ALLOWED TO EXPIRE, RAIN SHOWERS TO CONTINUE OVERNIGHT WITH ACCUMULATING SNOW IN THE FOOTHILLS - Message 1's will be allowed to expire at 8pm as the heavy rainfall threat from thunderstorms has ended with a long duration, light to moderate rainfall event expected to unfold overnight into the the day on Monday. - Now that temperatures have cooled into the 40's most areas, thunderstorm activity is diminishing and a widespread rain will develop over the District. A steady rain will fill in this evening and continue through the overnight with some lulls at times early on. Rain will generally fall at rates of 0.1-0.3"/hr into Monday morning. Additional rainfall on top of what has already occurred today expected to range from 0.5-1.5" through noon Monday, favoring areas W of I-25 and S of I-70 for higher end totals. - The snow line will be lowering this evening to around 8,000-9,000ft between 10pm and midnight and between 7,000-8,000ft between midnight and 2am Monday. By daybreak Monday the snow line may be as low as 6,000' briefly before slowly rising as the morning progresses. Best chances for widespread rain/snow pending elevation will be through noon then become more isolated into the afternoon before drying out in the evening. STORM RAINFALL POTENTIAL AND DURATION: Steady rain and weak thunderstorms will have the potential to produce 0.1-0.3" of rain in 60 minutes. WORST CASE SCENARIO: Moderate to heavy non-thunderstorm rain may result in up to 1.0" of rain 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 60-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Arapahoe Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Boulder Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Broomfield Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Denver Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Douglas Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Jefferson Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Foothills above 6500ft       Boulder Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Douglas Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Jefferson Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]