Time: 613 PM Wed May 10, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S COTNINUE VALID FOR THE ENTIRE DISTRICT UNTIL MIDNIGHT/MAY BE EXTENDED IF CONDITIONS WARRANT Strong to severe thunderstorms with large hail and moderate to heavy rainfall with multiple tornado warned storms by the NWS moved through the District this afternoon. The strong to severe thunderstorms have moved to the NE out of the District as of 6:00pm leaving a cool air mass in their wake with temperatures in the 50’s plains and 40’s foothills. The threat for strong thunderstorms with hail and heavy rainfall is diminishing now the atmosphere has been churned and temperatures are cooling leaving scattered to widespread rain showers and weak to moderate thunderstorms to continue into the evening and overnight period. With a moist atmosphere in place even weak to moderate thunderstorms will be capable of producing heavy rainfall this evening keeping the Message 1’s valid. There is a chance that Message 1’s may need to be extended as we approach midnight into Thursday morning depending upon how conditions play out over the next 4-6 hours. Now that the ground is becoming saturated in some locations that experienced heavy rain and hail earlier today it may not take as much rain to produce excessive runoff this evening and overnight. STORM RAINFALL POTENTIAL AND DURATION: Rain showers will produce a trace to 0.2" in 10-30 minutes. Weak thunderstorms will have the potential to produce 0.2-0.4" in 10-30 minutes. Moderate to briefly strong thunderstorms will have the potential to produce rainfall rates of 0.4-1.0" in 10-30 minutes. WORST CASE SCENARIO: A slower moving or nearly stationary thunderstorm or training of thunderstorm cells has the potential to produce up to 2.0" 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Denver County 1 100 PM TO 1159 PM Current TO 1130 PM Douglas County 1 100 PM TO 1159 PM Current TO 1130 PM Adams County 1 100 PM TO 1159 PM Current TO 1130 PM Broomfield County 1 100 PM TO 1159 PM Current TO 1130 PM Jefferson County 1 100 PM TO 1159 PM Current TO 1130 PM Boulder County 1 100 PM TO 1159 PM Current TO 1130 PM DIA 1 100 PM TO 1159 PM Current TO 1130 PM Arapahoe County 1 100 PM TO 1159 PM Current TO 1130 PM the City of Aurora 1 100 PM TO 1159 PM Current TO 1130 PM Arvada 1 100 PM TO 1159 PM Current TO 1130 PM Wheat Ridge 1 100 PM TO 1159 PM Current TO 1130 PM Lakewood 1 100 PM TO 1159 PM Current TO 1130 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Arapahoe Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Boulder Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Broomfield Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Denver Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Douglas Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Jefferson Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Foothills above 6500ft       Boulder Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Douglas Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) ISSUED Jefferson Current TO 1159 PM WED 0.1" (100%) to 0.4" (50%) to 1" (15%) 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]