Flash Flood Prediction Program

Time: 915 AM Thu May 4, 2023 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- CLOUDY/COOLER WITH RAIN SHOWERS AND ISOLATED TO WIDELY SCATTERED THUNDERSTORMS An upper level disturbance is moving through the District today and will result in light rain showers this morning with additional rain showers and isolated to widely scattered thunderstorms this afternoon. Temperatures will be held down with the cloud cover with afternoon highs reaching the upper 60’s to lower 70’s over the plains with 50’s and 60’s in the Front Range foothills. Rain showers will be widely scattered this morning and light with a chance for thunderstorms developing by around noon and continuing possible until around 8:00 PM this evening. Intermittent showers and thunderstorms are expected through the day with stronger thunderstorms this afternoon capable of producing brief moderate rain and possibly small hail which may result in minor runoff. After 8:00 PM this evening the chances for precipitation will decrease with dry weather expected ahead of midnight. Total precipitation through the day is expected to be in the 0.1-0.4" range with isolated higher amounts possible under thunderstorms. Showers and thunderstorms will move from S to N through early afternoon and then upper level steering winds will be more SW to NE mid to late afternoon between 10-20mph. STORM RAINFALL POTENTIAL AND DURATION: Rain showers will produce a trace to 0.1” in 30 minutes. Weak to moderate thunderstorms will have the potential to produce rainfall rates of 0.1-0.3” in 10-30 minutes. Although unlikely a stronger thunderstorm will have the capability to produce 0.2-0.5” in 10-30 minutes. WORST CASE SCENARIO: A slower moving strong thunderstorm or training of moderate to strong thunderstorm cells may result in up to 0.3-0.7” in 10-30 minutes and up to 1.0” in 60 minutes or less. A LOOK AHEAD: Drier and warmer on Friday with best chances for thunderstorms north of the District but there will still be a modest chance for an isolated late afternoon or evening thunderstorm, favoring areas N of I-70. Temperatures will warm well into the 70’s over the plains with mostly sunny skies early becoming partly to mostly cloudy late. Daily chances for afternoon showers and thunderstorms will continue over the weekend into early next week. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Arapahoe Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Boulder Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Broomfield Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Denver Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Douglas Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Jefferson Current TO 800 PM THU 0.01" (100%) to 0.2" (50%) to 0.4" (15%) LOW Foothills above 6500ft       Boulder Current TO 800 PM THU 0.01" (100%) to 0.2" (60%) to 0.4" (20%) LOW Douglas Current TO 800 PM THU 0.01" (100%) to 0.2" (60%) to 0.4" (20%) LOW Jefferson Current TO 800 PM THU 0.01" (100%) to 0.2" (60%) to 0.4" (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]