Time: 235 PM Tue June 6, 2023 Forecaster: Brad Simmons ------------------------- 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 be valid until 9:00 PM this evening. Thunderstorms have developed over the foothills but are very slow moving and these initial storms will likely not be the storms that impact the I-25 corridor later this afternoon. Rain cooled air from these initial storms in the form of a gust front/outflow boundary pushing eastward and acting as a “trigger” will be the likely culprit for new storm development over the plains. Storms will be slow moving from W to E or may remain nearly stationary and have the potential to produce heavy rainfall as surface moisture remains abundant with dew points in the 50’s. Best chances for thunderstorms over the plains will be from 3:30-8:30 PM. Due to all of the rainfall yesterday the ground is saturated in some areas and it may not take as much rain today to produce excessive runoff and possibly flash flooding. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce 0.1-0.4" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.4-1.2” in 10-30 minutes. WORST CASE SCENARIO: A slow moving strong thunderstorm or nearly stationary thunderstorm may result in up to 2.0” of rain in 60 minutes or less. COUNTY MESSAGE VALID TIMES PRIME TIME the City of Aurora 1 225 PM TO 900 PM 330 PM TO 830 PM Arapahoe County 1 225 PM TO 900 PM 330 PM TO 830 PM DIA 1 225 PM TO 900 PM 330 PM TO 830 PM Denver County 1 225 PM TO 900 PM 330 PM TO 830 PM Adams County 1 225 PM TO 900 PM 330 PM TO 830 PM Douglas County 1 225 PM TO 900 PM 330 PM TO 830 PM Broomfield County 1 225 PM TO 900 PM 330 PM TO 830 PM Jefferson County 1 225 PM TO 900 PM 330 PM TO 830 PM Boulder County 1 225 PM TO 900 PM 330 PM TO 830 PM Arvada 1 225 PM TO 900 PM 330 PM TO 830 PM Wheat Ridge 1 225 PM TO 900 PM 330 PM TO 830 PM Lakewood 1 225 PM TO 900 PM 330 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Arapahoe 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Boulder 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Broomfield 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Denver 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Douglas 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Jefferson 300 PM TO 900 PM 0.1" (80%) to 0.4" (50%) to 1.2" (25%) ISSUED Foothills above 6500ft       Boulder 300 PM TO 900 PM 0.1" (90%) to 0.4" (60%) to 1.2" (25%) ISSUED Douglas 300 PM TO 900 PM 0.1" (90%) to 0.4" (60%) to 1.2" (25%) ISSUED Jefferson 300 PM TO 900 PM 0.1" (90%) to 0.4" (60%) to 1.2" (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]