Flash Flood Prediction Program

Time: 854 AM Thu June 1, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ISOLATED SHOWERS THIS MORNING WITH THUNDERSTORMS LIKELY THIS AFTERNOON AND EVENING Cloudy and cool this morning with a few scattered showers, favoring areas north of I-70 at this time. These showers should slowly move northward through the morning before another round of afternoon thunderstorms with showers/isolated thunderstorms likely continuing into the evening. Similar to yesterday, storms will move from south to north between 5-15mph, with some erratic storm motions possible as storms form along outflow boundaries. These erratic storms will have the best opportunity for longer lasting moderate to heavy rainfall today as they generally anchor in place for an extended period of time. The best chance for impactful storms will be between 2-8pm with some lingering light to moderate showers likely through midnight. Typical weak to moderate thunderstorms this afternoon will produce light to moderate rain and gusty winds. Stronger thunderstorms will be capable of producing brief heavy rainfall and may become severe with large hail and winds in excess of 50mph. Overnight lows will drop into the upper 40’s to low 50’s on the plains with low to mid 40’s along the higher terrain and into the foothills. A few off and on light showers will be possible into daybreak Friday, however there is currently no threat for heavy rainfall through the overnight hours. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm formed along an outflow boundary may result in up to 1.6” of rain in 45-75 minutes. A LOOK AHEAD: This active weather pattern will continue Friday bringing another decent chance for showers and thunderstorms Friday with at least a LOW chance for isolated heavy rainfall. Similar conditions remain in place on Saturday. However, daytime temperatures will dictate the storm intensities as mostly cloudy and off and on rain showers will likely impact the District throughout the day. If we do see enough sunshine during the day, chances will increase of a heavy rainfall threat. This pattern holds Sunday with another good chance for off and on rain showers throughout most of the day Sunday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Arapahoe 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Boulder 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Broomfield 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Denver 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Douglas 200 PM TO 800 PM 0.1" (70%) to 0.3" (50%) to 0.8" (20%) MOD Jefferson 200 PM TO 800 PM 0.1" (70%) to 0.3" (50%) to 0.8" (20%) MOD Foothills above 6500ft       Boulder 200 PM TO 800 PM 0.1" (90%) to 0.3" (80%) to 0.8" (40%) MOD Douglas 200 PM TO 800 PM 0.1" (70%) to 0.3" (60%) to 0.8" (20%) MOD Jefferson 200 PM TO 800 PM 0.1" (80%) to 0.3" (70%) to 0.8" (30%) 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]