Flash Flood Prediction Program

Time: 140 PM Thu August 3, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1’S HAVE BEEN ISSUED EFFECTIVE UNTIL 7:00 PM Message 1’s have been issued effective until 7pm as there is a threat of heavy rainfall. Storms have initiated along western portions of the District today and will be moving eastward through the afternoon and early evening. Dew points at this time are well in the 50’s with around 60 by DIA. Strong upper-level support sits just east of the District, out on the eastern plains where strong to severe storms are likely. A chance for moderate to brief heavy rainfall within the District this afternoon and early evening. The best chance will be from now until 6pm with storms quickly moving east this evening and out of the District. A slight chance a storm could become severe inside the District, mainly for gusty winds and hail up to 1”. Storm motions will generally be from west to east between 15-25mph with some erratic storm movements possible along gust fronts. These storms will have the best chance of producing longer lasting heavy rainfall. STORM RAINFALL POTENTIAL AND DURATION: Typical showers/thunderstorms will produce a 0.05-0.25” total in 10 to 30 minutes. A moderate thunderstorm will produce 0.25” to 0.50” total in 10 to 30 minutes. A strong thunderstorm will produce 0.50” to 1.00” total in 10 to 30 minutes. WORST CASE SCENARIO: An anchored strong thunderstorm or training of thunderstorm cells has the potential to produce up to 1.5” in under 60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 700 PM 200 PM TO 600 PM Jefferson County 1 Current TO 700 PM 200 PM TO 600 PM Broomfield County 1 Current TO 700 PM 200 PM TO 600 PM Douglas County 1 Current TO 700 PM 200 PM TO 600 PM Adams County 1 Current TO 700 PM 200 PM TO 600 PM Denver County 1 Current TO 700 PM 200 PM TO 600 PM DIA 1 Current TO 700 PM 200 PM TO 600 PM Arapahoe County 1 Current TO 700 PM 200 PM TO 600 PM the City of Aurora 1 Current TO 700 PM 200 PM TO 600 PM Arvada 1 Current TO 700 PM 200 PM TO 600 PM Wheat Ridge 1 Current TO 700 PM 200 PM TO 600 PM Lakewood 1 Current TO 700 PM 200 PM TO 600 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 700 PM THU 0.25" (75%) to 0.5" (40%) to 1" (20%) ISSUED Arapahoe Current TO 700 PM THU 0.25" (75%) to 0.5" (40%) to 1" (20%) ISSUED Boulder Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Broomfield Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Denver Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Douglas Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Jefferson Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Foothills above 6500ft       Boulder Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Douglas Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) ISSUED Jefferson Current TO 700 PM THU 0.25" (60%) to 0.5" (30%) to 1" (15%) 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]