Time: 819 PM Tue May 9, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S CONTINUE VALID Message 1’s will continue valid for the next few hours but may be cancelled early if conditions remain quiet over the District. Strong thunderstorms developed over parts of Adams and Denver Counties late this afternoon and produced large hail as well as moderate to heavy rainfall. These strong thunderstorms have moved out of the District but these storms also produced an outflow boundary which has pushed westward into the foothills and may be a trigger to generate additional thunderstorms this evening. If this outflow boundary does not result in new thunderstorm development Message 1’s may be cancelled early as they are currently valid until 2:00 AM Wednesday. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.4" of rain in 30-60 minutes. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.4-0.8" in 10-30 minutes. WORST CASE SCENARIO: A slow moving strong thunderstorm or training of thunderstorm cells may result in up to 1.5" of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Jefferson County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Broomfield County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Douglas County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Adams County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Denver County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM DIA 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Arapahoe County 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM the City of Aurora 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Arvada 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Wheat Ridge 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM Lakewood 1 Current TO 200 AM WEDNESDAY Current TO 1100 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1159 PM TUE 0.1" (50%) to 0.4" (25%) to 0.8" (10%) ISSUED Arapahoe Current TO 1159 PM TUE 0.1" (40%) to 0.4" (20%) to 0.8" (5%) ISSUED Boulder Current TO 1159 PM TUE 0.1" (65%) to 0.4" (30%) to 0.8" (15%) ISSUED Broomfield Current TO 1159 PM TUE 0.1" (60%) to 0.4" (30%) to 0.8" (15%) ISSUED Denver Current TO 1159 PM TUE 0.1" (50%) to 0.4" (25%) to 0.8" (10%) ISSUED Douglas Current TO 1159 PM TUE 0.1" (30%) to 0.4" (15%) to 0.8" (5%) ISSUED Jefferson Current TO 1159 PM TUE 0.1" (50%) to 0.4" (25%) to 0.8" (10%) ISSUED Foothills above 6500ft       Boulder Current TO 1159 PM TUE 0.1" (70%) to 0.4" (30%) to 0.8" (15%) ISSUED Douglas Current TO 1159 PM TUE 0.1" (40%) to 0.4" (20%) to 0.8" (5%) ISSUED Jefferson Current TO 1159 PM TUE 0.1" (50%) to 0.4" (25%) 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]