Time: 754 PM Sat May 27, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S HAVE BEEN EXTENDED UNTIL 9:30PM FOR THE ENTIRE DISTRICT Message 1’s have been extended until 9:30pm for the entire District. Surface wind convergence resides over the District currently and is generating new thunderstorm development. Stronger thunderstorms may still produce moderate to brief heavy rainfall into the evening as well as hail and gusty winds. A large thunderstorm or training of thunderstorm cells will be the most likely culprits for extended periods of heavy rain over the next 1-2 hours. Typical storms will move from SW to NE at around 20mph, but stronger storms may move more slowly. Thunderstorm activity is expected to decrease between 9-10pm and eventually move east of the District. If thunderstorms still persist past 9:30pm Message 1’s may be extended further. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce 0.1-0.3" of rain. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes. WORST CASE SCENARIO: A slow moving strong thunderstorm or large thunderstorm cell may result in up to 1.5” of rain in 45-60 minutes COUNTY MESSAGE VALID TIMES PRIME TIME Arapahoe County 1 319 PM TO 930 PM 330 PM TO 900 PM the City of Aurora 1 319 PM TO 930 PM 330 PM TO 900 PM DIA 1 319 PM TO 930 PM 330 PM TO 900 PM Denver County 1 319 PM TO 930 PM 330 PM TO 900 PM Adams County 1 319 PM TO 930 PM 330 PM TO 900 PM Douglas County 1 319 PM TO 930 PM 330 PM TO 900 PM Broomfield County 1 319 PM TO 930 PM 330 PM TO 900 PM Jefferson County 1 319 PM TO 930 PM 330 PM TO 900 PM Boulder County 1 319 PM TO 930 PM 330 PM TO 900 PM Lakewood 1 319 PM TO 930 PM 330 PM TO 900 PM Wheat Ridge 1 319 PM TO 930 PM 330 PM TO 900 PM Arvada 1 319 PM TO 930 PM 330 PM TO 900 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 930 PM SAT 0.1" (75%) to 0.3" (40%) to 0.8" (20%) ISSUED Arapahoe Current TO 930 PM SAT 0.1" (75%) to 0.3" (40%) to 0.8" (20%) ISSUED Boulder Current TO 930 PM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (10%) ISSUED Broomfield Current TO 930 PM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (10%) ISSUED Denver Current TO 930 PM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Douglas Current TO 930 PM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Jefferson Current TO 930 PM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Foothills above 6500ft       Boulder Current TO 930 PM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (10%) ISSUED Douglas Current TO 930 PM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (10%) ISSUED Jefferson Current TO 930 PM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (10%) 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]