Flash Flood Prediction Program

Time: 230 PM Thu May 25, 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 9:30pm. Thunderstorms are expected to develop over the next few hours and move through the District into the evening. Elevated surface moisture levels with dew points in the upper 40’s to around 50 will result in thunderstorms that develop today having the potential to produce brief heavy rainfall that may result in excessive runoff and possibly flash flooding. Strong thunderstorms may also contain hail and gusty winds. Generally, one round of thunderstorms is expected but some areas may experience a couple of rounds of storms. After 9:30pm the thunderstorm activity is expected to have moved east of the District with additional lighter rain showers remaining possible until around midnight. STORM RAINFALL POTENTIAL AND DURATION: Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.4-1.0” in 10-30 minutes. WORST CASE SCENARIO: A slow moving strong thunderstorm or a large thunderstorm may result in up to 1.8” of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Lakewood 1 230 PM TO 930 PM 330 PM TO 830 PM Wheat Ridge 1 230 PM TO 930 PM 330 PM TO 830 PM Arvada 1 230 PM TO 930 PM 330 PM TO 830 PM the City of Aurora 1 230 PM TO 930 PM 330 PM TO 830 PM Arapahoe County 1 230 PM TO 930 PM 330 PM TO 830 PM Denver County 1 230 PM TO 930 PM 330 PM TO 830 PM DIA 1 230 PM TO 930 PM 330 PM TO 830 PM Adams County 1 230 PM TO 930 PM 330 PM TO 830 PM Douglas County 1 230 PM TO 930 PM 330 PM TO 830 PM Broomfield County 1 230 PM TO 930 PM 330 PM TO 830 PM Jefferson County 1 230 PM TO 930 PM 330 PM TO 830 PM Boulder County 1 230 PM TO 930 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 930 PM 0.1" (85%) to 0.4" (50%) to 1" (20%) ISSUED Arapahoe 300 PM TO 930 PM 0.1" (90%) to 0.4" (60%) to 1" (30%) ISSUED Boulder 300 PM TO 930 PM 0.1" (85%) to 0.4" (50%) to 1" (20%) ISSUED Broomfield 300 PM TO 930 PM 0.1" (85%) to 0.4" (50%) to 1" (20%) ISSUED Denver 300 PM TO 930 PM 0.1" (85%) to 0.4" (50%) to 1" (20%) ISSUED Douglas 300 PM TO 930 PM 0.1" (90%) to 0.4" (60%) to 1" (30%) ISSUED Jefferson 300 PM TO 930 PM 0.1" (85%) to 0.4" (50%) to 1" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 930 PM THU 0.1" (90%) to 0.4" (60%) to 1" (30%) ISSUED Douglas Current TO 930 PM THU 0.1" (90%) to 0.4" (60%) to 1" (30%) ISSUED Jefferson Current TO 930 PM THU 0.1" (90%) to 0.4" (60%) to 1" (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]