Time: 244 PM Thu June 20, 2024 Forecaster: Aaron O'Brien ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1’S HAVE BEEN ISSUED EFFECTIVE UNTIL 10:00 PM Message 1’s have been issued for the entire District effective until 10:00pm for the threat for heavy rainfall with the potential for severe storms across the District this afternoon and evening. The best chance for any shower/thunderstorm activity withing the District will be between 3pm-9pm with a few lingering showers possible through 2am. The best chance for heavy rainfall will be throughout the entire message period. Storm motions will be southwest to northeast between 15-20 mph. Outflow boundaries will likely produce erratic storm movement and clustering thunderstorms which will increase chances for heavy rainfall. Due to updated current conditions, values will be increased from the current message 1. Severe storms will also contain isolated heavy rainfall with the largest threat being stationary heavy rainfall creating a quick 0.50-1.00" in 10-15 minutes. STORM RAINFALL POTENTIAL AND DURATION: Typical showers and thunderstorms will produce a 0.25-0.75” total in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.75-1.25" total in 10-30 minutes. WORST CASE SCENARIO: A strong, stationary thunderstorm, or training of thunderstorm cells will have the potential to produce up to 1.50-2.00” total in 30-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 1000 PM Current TO 900 PM Jefferson County 1 Current TO 1000 PM Current TO 900 PM Broomfield County 1 Current TO 1000 PM Current TO 900 PM Douglas County 1 Current TO 1000 PM Current TO 900 PM Adams County 1 Current TO 1000 PM Current TO 900 PM Denver County 1 Current TO 1000 PM Current TO 900 PM DIA 1 Current TO 1000 PM Current TO 900 PM Arapahoe County 1 Current TO 1000 PM Current TO 900 PM the City of Aurora 1 Current TO 1000 PM Current TO 900 PM Arvada 1 Current TO 1000 PM Current TO 900 PM Wheat Ridge 1 Current TO 1000 PM Current TO 900 PM Lakewood 1 Current TO 1000 PM Current TO 900 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Arapahoe Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Boulder Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Broomfield Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Denver Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Douglas Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Jefferson Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Douglas Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) ISSUED Jefferson Current TO 900 PM THU 0.5" (75%) to 0.75" (50%) to 1.25" (25%) 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]