Time: 915 AM Sat July 23, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- RELIEF FROM THE HEAT THIS AFTERNOON AS MULTIPLE ROUNDS OF STORMS TO MOVE THROUGH - The streak of 90-degree plus days will continue for one more day with highs warming well into the 90's over the plains ahead of shower and thunderstorm development this afternoon which will provide relief from the heat. - Thunderstorms will begin to develop over the mountains and foothills ahead of noon and then spread out onto the plains between noon-1pm. 1-3 rounds of showers and thunderstorms are expected between 1-9pm with lingering rain showers possible until about midnight. Moisture will be on the increase as the day progresses resulting in stronger storms capable of producing brief heavy rainfall. More typical storms will produce light to moderate rain and gusty winds. - Upper level steering winds will be from W to E at 15-20mph keeping the majority of the storms moving along and helping to reduce point rainfall amounts from a single storm. Training of thunderstorm cells or a briefly anchored thunderstorm will be the main culprits for extended periods of heavy rainfall resulting in a LOW to MODERATE risk for excessive runoff. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3" of moisture. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: Training of thunderstorm cells or a briefly anchored strong thunderstorm may result in up to 1.5" of heavy rain in 45-60 minutes. A LOOK AHEAD: Temperatures will back off into the 80's for highs on Sunday and moisture will increase further leading to an active thunderstorm day. Scattered to numerous thunderstorms are expected in the afternoon, some of which may become strong to severe and will be very capable of producing heavy rainfall that may lead to excessive runoff and possibly flash flooding. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (15%) LOW Arapahoe 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (15%) LOW Boulder 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (20%) MOD Broomfield 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (15%) LOW Denver 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (15%) LOW Douglas 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (20%) MOD Jefferson 100 PM TO 900 PM Trace (95%) to 0.3" (60%) to 0.8" (20%) MOD Foothills above 6500ft       Boulder 1200 PM TO 900 PM Trace (100%) to 0.3" (75%) to 0.8" (25%) MOD Douglas 1200 PM TO 900 PM Trace (100%) to 0.3" (75%) to 0.8" (25%) MOD Jefferson 1200 PM TO 900 PM Trace (100%) to 0.3" (75%) to 0.8" (25%) MOD MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]