Flash Flood Prediction Program

Time: 459 PM Thu September 15, 2022 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S CONTINUE VALID/THUNDERSTORM CHANCES DIMINISHING INTO THE EVENING - Message 1's will continue valid until 8:00 PM but the threat for heavy rainfall from thunderstorms is diminishing. - Strongest storms today remained to the E and SE of the District over Elbert and eastern Arapahoe Counties. These storms have produced a gust front which is pushing back to the NW but is failing to produce any additional storms. - Surface moisture has decreased from earlier this afternoon and with temperatures at or just past their peak the threat for thunderstorms will be lowering into the evening. Should a thunderstorm develop over the next 2-3 hours it will still be capable of producing heavy rainfall but much of the available energy has been tapped by storms outside the District. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce 0.1-0.2" of rain. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.2-0.6" in 10-30 minutes. WORST CASE SCENARIO: A slower moving strong thunderstorm or training of thunderstorm cells has the potential to produce up to 1.0" of rain in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 200 PM TO 800 PM 230 PM TO 730 PM Jefferson County 1 200 PM TO 800 PM 230 PM TO 730 PM Broomfield County 1 200 PM TO 800 PM 230 PM TO 730 PM Douglas County 1 200 PM TO 800 PM 230 PM TO 730 PM Adams County 1 200 PM TO 800 PM 230 PM TO 730 PM Denver County 1 200 PM TO 800 PM 230 PM TO 730 PM DIA 1 200 PM TO 800 PM 230 PM TO 730 PM Arapahoe County 1 200 PM TO 800 PM 230 PM TO 730 PM the City of Aurora 1 200 PM TO 800 PM 230 PM TO 730 PM Arvada 1 200 PM TO 800 PM 230 PM TO 730 PM Wheat Ridge 1 200 PM TO 800 PM 230 PM TO 730 PM Lakewood 1 200 PM TO 800 PM 230 PM TO 730 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 800 PM THU Trace (40%) to 0.3" (20%) to 0.6" (10%) ISSUED Arapahoe Current TO 800 PM THU Trace (40%) to 0.3" (20%) to 0.6" (10%) ISSUED Boulder Current TO 800 PM THU Trace (50%) to 0.3" (25%) to 0.6" (10%) ISSUED Broomfield Current TO 800 PM THU Trace (40%) to 0.3" (20%) to 0.6" (10%) ISSUED Denver Current TO 800 PM THU Trace (40%) to 0.3" (20%) to 0.6" (10%) ISSUED Douglas Current TO 800 PM THU Trace (50%) to 0.3" (25%) to 0.6" (10%) ISSUED Jefferson Current TO 800 PM THU Trace (50%) to 0.3" (25%) to 0.6" (10%) ISSUED Foothills above 6500ft       Boulder Current TO 800 PM THU Trace (60%) to 0.3" (30%) to 0.6" (10%) ISSUED Douglas Current TO 800 PM THU Trace (60%) to 0.3" (30%) to 0.6" (10%) ISSUED Jefferson Current TO 800 PM THU Trace (60%) to 0.3" (30%) to 0.6" (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]