Flash Flood Prediction Program

Time: 206 PM Wed June 7, 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 10:00 PM this evening. Thunderstorms to the south of the District have developed over the crest of the Palmer Divide and have produced a rain cooled outflow boundary that is moving to the N and will enter the District over the next hour. This boundary will likely initiate new thunderstorm development as it progresses northward this afternoon with slow moving, strong storms possible into the evening. Best chances for thunderstorms will be through 9 or 10:00 PM with additional lighter rain showers continuing into the early overnight period. Upper level steering winds are very light from S/SSE to N/NNW at 10mph or less. Strong thunderstorms may move very little or remain stationary. The slow motion of the storms may result in extended periods of heavy rainfall that may lead to excessive runoff and possibly flash flooding. The ground is also saturated over many areas within the District and it may not take as much rain as normal to produce runoff. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce rainfall rates of 0.1-0.5” 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 or nearly stationary strong thunderstorm may result in up to 2.0” of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 1000 PM 300 PM TO 900 PM Jefferson County 1 Current TO 1000 PM 300 PM TO 900 PM Broomfield County 1 Current TO 1000 PM 300 PM TO 900 PM Douglas County 1 Current TO 1000 PM 300 PM TO 900 PM Adams County 1 Current TO 1000 PM 300 PM TO 900 PM Denver County 1 Current TO 1000 PM 300 PM TO 900 PM DIA 1 Current TO 1000 PM 300 PM TO 900 PM Arapahoe County 1 Current TO 1000 PM 300 PM TO 900 PM the City of Aurora 1 Current TO 1000 PM 300 PM TO 900 PM Arvada 1 Current TO 1000 PM 300 PM TO 900 PM Wheat Ridge 1 Current TO 1000 PM 300 PM TO 900 PM Lakewood 1 Current TO 1000 PM 300 PM TO 900 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 1000 PM 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Broomfield 300 PM TO 1000 PM 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Arapahoe 230 PM TO 1000 PM 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Boulder 230 PM TO 1000 PM 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Denver 230 PM TO 1000 PM 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Jefferson 230 PM TO 1000 PM 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Douglas Current TO 1000 PM WED 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Foothills above 6500ft       Boulder Current TO 1000 PM WED 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Douglas Current TO 1000 PM WED 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH Jefferson Current TO 1000 PM WED 0.1" (80%) to 0.5" (50%) to 1.3" (25%) HIGH MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]