Flash Flood Prediction Program

Time: 113 PM Sun August 21, 2022 Forecaster: Justin Brooks ------------------------- 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. - Storms have initiated over the higher terrain at this time and should continue to build over the next hour before moving into the District. Best chance for storms in the District will start around 2pm and could last through 9pm before chances start to taper off into the late evening hours. Some cloud cover this morning could help keep the stronger storms at bay, although even weak to moderate storms will produce brief heavy rainfall. - Storm motions will generally be SW to NE, however, very week steering winds will likely result in nearly stationary storms at times. these slow storm motions and relatively high moisture values at the surface and aloft will result in thunderstorms that have the potential to produce heavy rainfall that may result in excessive runoff. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will only produce a 0.1-0.4" of rainfall in 10-30 minutes. Moderate to strong rain showers/thunderstorms will have the potential to produce rainfall rates of 0.4-1.2" in 10-30 minutes. WORST CASE SCENARIO: A strong, stationary thunderstorm or training of thunderstorm may result in up to 2.5" of heavy rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 100 PM TO 900 PM 200 PM TO 830 PM Jefferson County 1 100 PM TO 900 PM 200 PM TO 830 PM Broomfield County 1 100 PM TO 900 PM 200 PM TO 830 PM Douglas County 1 100 PM TO 900 PM 200 PM TO 830 PM Adams County 1 100 PM TO 900 PM 200 PM TO 830 PM Denver County 1 100 PM TO 900 PM 200 PM TO 830 PM DIA 1 100 PM TO 900 PM 200 PM TO 830 PM Arapahoe County 1 100 PM TO 900 PM 200 PM TO 830 PM the City of Aurora 1 100 PM TO 900 PM 200 PM TO 830 PM Arvada 1 100 PM TO 900 PM 200 PM TO 830 PM Wheat Ridge 1 100 PM TO 900 PM 200 PM TO 830 PM Lakewood 1 100 PM TO 900 PM 200 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 900 PM 0.1" (60%) to 0.4" (40%) to 1.2" (10%) ISSUED Arapahoe 100 PM TO 900 PM 0.1" (60%) to 0.4" (40%) to 1.2" (10%) ISSUED Boulder 100 PM TO 900 PM 0.1" (80%) to 0.4" (60%) to 1.2" (20%) ISSUED Broomfield 100 PM TO 900 PM 0.1" (70%) to 0.4" (50%) to 1.2" (15%) ISSUED Denver 100 PM TO 900 PM 0.1" (60%) to 0.4" (40%) to 1.2" (10%) ISSUED Douglas 100 PM TO 900 PM 0.1" (80%) to 0.4" (60%) to 1.2" (20%) ISSUED Jefferson 100 PM TO 900 PM 0.1" (80%) to 0.4" (60%) to 1.2" (20%) ISSUED Foothills above 6500ft       Boulder 100 PM TO 900 PM 0.1" (80%) to 0.4" (60%) to 1.2" (20%) ISSUED Douglas 100 PM TO 900 PM 0.1" (80%) to 0.4" (60%) to 1.2" (20%) ISSUED Jefferson 100 PM TO 900 PM 0.1" (80%) to 0.4" (60%) to 1.2" (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]