Flash Flood Prediction Program

Time: 221 PM Wed August 2, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- ANOTHER GOOD CHANCE FOR SHOWERS/THUNDERSTORMS ACROSS THE DISTRICT THIS AFTERNOON AND EVENING. Message 1’s have been issued for the entire District effective until 9pm. A few isolated storms have formed along the higher terrain west of the District and will move through the District over the next several hours before storm chances taper off after sundown. A couple of rounds of storms will be possible through the evening with a slight chance for a few off and on showers through the overnight. Storms will be hit or miss today, leading to some areas likely staying dry. A boundary has been set up along the eastern portion of the District which will be a focal point for stronger storm development heading into the late afternoon/early evening. Storm motions will typically be from west to east between 10-20mph, which should help limit point rainfall amounts. However, additional storms that form along outflow boundaries have the potential to stall out and bring moderate to heavy rainfall for an extended period of time. These storms will likely have the best chance of heavy rainfall leading to LOW IMPACT FLOODING with both threats of a quick 0.5” in 10-15 minutes. The best chance for stronger storms will be from the initial wave of storms, with subsequent waves of showers decreasing with intensity through the evening. STORM RAINFALL POTENTIAL AND DURATION: Typical showers/weak thunderstorms will produce a 0.05-0.25” total, in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.25-0.75” total in 10-30 minutes. Strong thunderstorms will produce 0.75-1.50” total in 10-30 minutes. WORST CASE SCENARIO: A stronger, stalled out thunderstorm is able to develop and will have the potential to produce up to 2.50” total, in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Wheat Ridge 1 Current TO 900 PM Current TO 830 PM Lakewood 1 Current TO 900 PM Current TO 830 PM Arvada 1 Current TO 900 PM Current TO 830 PM the City of Aurora 1 Current TO 900 PM Current TO 830 PM Arapahoe County 1 Current TO 900 PM Current TO 830 PM DIA 1 Current TO 900 PM Current TO 830 PM Denver County 1 Current TO 900 PM Current TO 830 PM Adams County 1 Current TO 900 PM Current TO 830 PM Douglas County 1 Current TO 900 PM Current TO 830 PM Broomfield County 1 Current TO 900 PM Current TO 830 PM Jefferson County 1 Current TO 900 PM Current TO 830 PM Boulder County 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 WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Arapahoe Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Boulder Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Broomfield Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Denver Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Douglas Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Jefferson Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Douglas Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (10%) ISSUED Jefferson Current TO 900 PM WED 0.25" (50%) to 0.75" (25%) to 1.5" (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]