Flash Flood Prediction Program

Time: 832 AM Sun June 6, 2021 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- CONTINUED HOT WITH AN UPTICK IN THUNDERSTORM ACTIVITY - Conditions will remain unseasonably warm over the District today with highs reaching the upper 80's to around 90 with 70's in the Front Range foothills. There is a little more mid and upper level moisture to work with today and is expected to result in an uptick in thunderstorm activity compared to yesterday. - Thunderstorms will develop early over the foothills before noon. With relatively slow storm motions the initial activity is expected to remain over the higher terrain until early afternoon. By 1-2pm there will be a modest chance for thunderstorms over the plains. Isolated to widely scattered thunderstorm coverage is then expected into the early evening. Best chances for storms over the plains will be between 2-9pm. - Typical thunderstorms that develop today will produce light to moderate rain and gusty winds. An isolated strong thunderstorm will be capable of producing brief heavy rainfall and hail. A large, slower moving strong thunderstorm will be capable of producing an extended period of heavy rain that may lead to excessive runoff. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3" in 10-30 minutes. A strong thunderstorm will be capable of producing 0.3-0.9" of heavy rain in 10-30 minutes. WORST CASE SCENARIO: A large, slow moving thunderstorm will have the potential to produce up to 1.8" in 60 minutes or less. A LOOK AHEAD: Temperatures will warm a degree or two on Monday over the District with a decrease in afternoon thunderstorms. There will still be isolated afternoon thunderstorms between 2-8pm with a lesser chance for heavy rainfall. Tuesday is trending dry at this time over the plains but there could be a few higher elevation thunderstorms in the afternoon. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 900 PM 0.1" (65%) to 0.3" (40%) to 0.9" (10%) LOW Arapahoe 200 PM TO 900 PM 0.1" (70%) to 0.3" (50%) to 0.9" (10%) LOW Broomfield 200 PM TO 900 PM 0.1" (65%) to 0.3" (40%) to 0.9" (10%) LOW Denver 200 PM TO 900 PM 0.1" (65%) to 0.3" (40%) to 0.9" (10%) LOW Boulder 100 PM TO 900 PM 0.1" (65%) to 0.3" (40%) to 0.9" (10%) LOW Douglas 100 PM TO 900 PM 0.1" (75%) to 0.3" (50%) to 0.9" (15%) MOD Jefferson 100 PM TO 900 PM 0.1" (70%) to 0.3" (50%) to 0.9" (10%) LOW Foothills above 6500ft       Boulder 1200 PM TO 900 PM 0.1" (85%) to 0.3" (50%) to 0.9" (15%) MOD Douglas 1200 PM TO 900 PM 0.1" (85%) to 0.3" (50%) to 0.9" (15%) MOD Jefferson 1200 PM TO 900 PM 0.1" (85%) to 0.3" (50%) to 0.9" (15%) 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]