Time: 458 PM Sat July 15, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S HAVE BEEN ISSUED FOR THE ENTIRE DISTRICT Message 1’s have been issued for the entire District and will be valid until 9;00 PM this evening. A strong thunderstorm has entered Boulder County and will trek to the S/SE at 20-25mph and will encounter a surface wind convergence boundary that has set up over central portions of the Denver Metro area. This storm alone is capable of producing heavy rainfall but may result in additional thunderstorm activity and/or slower motions as it interacts with the wind convergence line over central areas of the District. A briefly anchored strong thunderstorm will produce the greatest threat for extended periods of heavy rainfall that may lead to excessive runoff. Typical thunderstorms will produce brief heavy rainfall, gusty winds and hail. Best chances for thunderstorm activity will be until 9:00 PM this evening. STORM RAINFALL POTENTIAL AND DURATION: Moderate to strong thunderstorms have the potential to produce heavy rainfall rates of 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A slower moving strong thunderstorm will have the potential to produce up to 1.5" in 45-60 minutes COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 900 PM Current TO 830 PM Jefferson County 1 Current TO 900 PM 530 PM TO 830 PM Broomfield County 1 Current TO 900 PM 530 PM TO 830 PM Douglas County 1 Current TO 900 PM 530 PM TO 830 PM Adams County 1 Current TO 900 PM 530 PM TO 830 PM Denver County 1 Current TO 900 PM 530 PM TO 830 PM DIA 1 Current TO 900 PM 530 PM TO 830 PM Arapahoe County 1 Current TO 900 PM 530 PM TO 830 PM the City of Aurora 1 Current TO 900 PM 530 PM TO 830 PM Arvada 1 Current TO 900 PM 530 PM TO 830 PM Wheat Ridge 1 Current TO 900 PM 530 PM TO 830 PM Lakewood 1 Current TO 900 PM 530 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM SAT 0.1" (85%) to 0.3" (50%) to 0.8" (25%) ISSUED Arapahoe Current TO 900 PM SAT 0.1" (75%) to 0.3" (40%) to 0.8" (15%) ISSUED Boulder Current TO 900 PM SAT 0.1" (95%) to 0.3" (60%) to 0.8" (30%) ISSUED Broomfield Current TO 900 PM SAT 0.1" (90%) to 0.3" (60%) to 0.8" (25%) ISSUED Denver Current TO 900 PM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (15%) ISSUED Douglas Current TO 900 PM SAT 0.1" (75%) to 0.3" (40%) to 0.8" (15%) ISSUED Jefferson Current TO 900 PM SAT 0.1" (75%) to 0.3" (40%) to 0.8" (15%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM SAT 0.1" (70%) to 0.3" (30%) to 0.8" (10%) ISSUED Douglas Current TO 900 PM SAT 0.1" (70%) to 0.3" (30%) to 0.8" (10%) ISSUED Jefferson Current TO 900 PM SAT 0.1" (70%) to 0.3" (30%) to 0.8" (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]