Time: 1200 PM Wed May 24, 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 8:00pm this evening. Abundant surface moisture with dew points in the low to mid 50’s and a passing upper level disturbance will result in thunderstorms developing initiating over the next 1-2 hours over the higher terrain to the W and S of the District. One round of moderate to strong thunderstorms is expected through the course of the afternoon with a weaker round possible in the evening. Typical thunderstorms will be relatively slow moving from SW to NE at around 15mph, but stronger thunderstorm cells may move slower and against the grain from NW to SE. Strong thunderstorms will be capable of producing heavy rainfall that may lead to excessive runoff and possibly flash flooding. After 8:00pm the thunderstorm activity is expected to have pushed east of the District with conditions drying out into the later evening. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce rainfall rates of 0.2-0.5” of rain in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.5-1.3” in 10-30 minutes. WORST CASE SCENARIO: A slow moving strong thunderstorm or training of thunderstorm cells may result in up to 2.0” of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME the City of Aurora 1 1200 PM TO 800 PM 100 PM TO 700 PM Arapahoe County 1 1200 PM TO 800 PM 100 PM TO 700 PM DIA 1 1200 PM TO 800 PM 100 PM TO 700 PM Denver County 1 1200 PM TO 800 PM 100 PM TO 700 PM Adams County 1 1200 PM TO 800 PM 100 PM TO 700 PM Douglas County 1 1200 PM TO 800 PM 100 PM TO 700 PM Broomfield County 1 1200 PM TO 800 PM 100 PM TO 700 PM Jefferson County 1 1200 PM TO 800 PM 100 PM TO 700 PM Boulder County 1 1200 PM TO 800 PM 100 PM TO 700 PM Lakewood 1 1200 PM TO 800 PM 100 PM TO 700 PM Arvada 1 1200 PM TO 800 PM 100 PM TO 700 PM Wheat Ridge 1 1200 PM TO 800 PM 100 PM TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (25%) ISSUED Arapahoe 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (25%) ISSUED Boulder 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (20%) ISSUED Broomfield 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (20%) ISSUED Denver 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (25%) ISSUED Douglas 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (25%) ISSUED Jefferson 100 PM TO 800 PM 0.1" (90%) to 0.5" (50%) to 1" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 800 PM WED 0.1" (95%) to 0.5" (50%) to 1" (20%) ISSUED Douglas Current TO 800 PM WED 0.1" (95%) to 0.5" (50%) to 1" (20%) ISSUED Jefferson Current TO 800 PM WED 0.1" (95%) to 0.5" (50%) to 1" (20%) 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]