Flash Flood Prediction Program

Time: 944 AM Fri August 5, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- NEAR RECORD HEAT ONCE AGAIN WITH ISOLATED AFTERNOON THUNDERSTORMS - After tying the record high of 98 degrees at DIA yesterday another record may be reached today. Temperatures this afternoon will top out in the mid to upper 90's over the plains with possibly an isolated 100 degree reading. The record high for Denver today is 99 degrees and it will be in jeopardy of being reached. Normal high for Denver today is 89 degrees. How early the cloud cover develops will be a determining factor if the record is reached today. - Much like yesterday the best chances for thunderstorms this afternoon will be over the foothills to the W and Palmer Divide to the S with only isolated coverage expected most areas withing the District itself. Typical storms will produce light to briefly moderate rain and gusty winds. Outflow from storms outside the District may increase moisture levels and provide a trigger for development which could produce a stronger thunderstorm that would be capable of producing heavy rain. The chances of this playing out are very low but is the reasoning behind a LOW Message potential today. - Thunderstorms will develop over the higher terrain to the W and SW between 1-3pm with chances for storm activity over the plains between 3-9pm. After 9pm dry conditions are expected. Upper level steering winds will be turning more SW as the day progresses and most storms will move from SW to NE at 10-20mph. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.2" of moisture. Moderate thunderstorms will have the potential to produce rainfall rates of 0.2-0.6" in 10-30 minutes. WORST CASE SCENARIO: Outflow from thunderstorms outside the District pushes additional moisture into the area and provides a triggering mechanism for strong thunderstorms with the potential to produce rainfall rates of 0.5-1.2" in 10-30 minutes and up to 2.0" in 45-60 minutes. A LOOK AHEAD: A cold front will move through overnight and cool temperatures into the upper 80's to lower 90's over the plains on Saturday and increase surface moisture. Monsoon moisture will move overhead and in tandem with the up-tick in surface moisture there is expected to be a significant increase in thunderstorm activity. Strong thunderstorms Saturday will be capable of producing heavy rainfall that may lead to excessive runoff. The threat for strong thunderstorms with the potential for heavy rainfall will continue Sunday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 900 PM Trace (60%) to 0.3" (20%) to 0.6" (5%) LOW Arapahoe 300 PM TO 900 PM Trace (60%) to 0.3" (20%) to 0.6" (5%) LOW Broomfield 300 PM TO 900 PM Trace (60%) to 0.3" (20%) to 0.6" (5%) LOW Denver 300 PM TO 900 PM Trace (60%) to 0.3" (20%) to 0.6" (5%) LOW Boulder 200 PM TO 900 PM Trace (65%) to 0.3" (30%) to 0.6" (10%) LOW Douglas 200 PM TO 900 PM Trace (65%) to 0.3" (30%) to 0.6" (10%) LOW Jefferson 200 PM TO 900 PM Trace (65%) to 0.3" (30%) to 0.6" (10%) LOW Foothills above 6500ft       Boulder 100 PM TO 900 PM Trace (80%) to 0.3" (40%) to 0.6" (15%) LOW Douglas 100 PM TO 900 PM Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW Jefferson 100 PM TO 900 PM Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]