Flash Flood Prediction Program

Time: 628 PM Sun July 25, 2021 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT - Message 1's have been issued for the entire District and will remain valid until 9pm this evening. - A gust front from the east has moved into the District this evening resulting in rapid storm development currently along the foothills. This storm development will continue over the next few hours and with very little storm movement, the chance for heavy rainfall has increased this evening. Additional storms could also develop along outflow boundaries for all areas of the District. - Slow to nearly stationary storm motions will allow for extended periods of heavy rain under stronger storms that are able to develop this afternoon/evening which may lead to excessive runoff and possibly flash flooding. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.2-0.6" in 10-30 minutes. Strong thunderstorms have the potential to produce 0.4-1.2" of heavy rain in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 2.4" in 60- 90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME 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 Douglas County 1 Current TO 900 PM Current TO 830 PM Adams County 1 Current TO 900 PM Current TO 830 PM Broomfield County 1 Current TO 900 PM Current TO 830 PM Arvada 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 Wheat Ridge 1 Current TO 900 PM Current TO 830 PM Lakewood 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 SUN 0.2" (30%) to 0.6" (10%) to 1.2" (5%) ISSUED Arapahoe Current TO 900 PM SUN 0.2" (50%) to 0.6" (25%) to 1.2" (10%) ISSUED Boulder Current TO 900 PM SUN 0.2" (75%) to 0.6" (40%) to 1.2" (20%) ISSUED Broomfield Current TO 900 PM SUN 0.2" (75%) to 0.6" (40%) to 1.2" (20%) ISSUED Denver Current TO 900 PM SUN 0.2" (50%) to 0.6" (25%) to 1.2" (10%) ISSUED Douglas Current TO 900 PM SUN 0.2" (75%) to 0.6" (40%) to 1.2" (20%) ISSUED Jefferson Current TO 900 PM SUN 0.2" (75%) to 0.6" (40%) to 1.2" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 900 PM SUN 0.2" (80%) to 0.6" (50%) to 1.2" (30%) ISSUED Douglas Current TO 900 PM SUN 0.2" (80%) to 0.6" (50%) to 1.2" (30%) ISSUED Jefferson Current TO 900 PM SUN 0.2" (80%) to 0.6" (50%) to 1.2" (30%) 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]