Time: 953 PM Wed June 28, 2023 Forecaster: Laura Smith ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ISOLATED THUNDERSTORMS IN THE AREA A few high-based showers/isolated thunderstorms are rolling off the foothills and into the district. This activity is expected to exit the District by 1130PM. Most if not all precipitation will struggle to reach the surface due to drying in the low levels. Additional isolated storms are possible if storms form again across the foothills. For the remainder of the overnight, a slight chance for showers and thunderstorms will persist through 400AM. Otherwise, overnight will be mild with temps dropping into the low to mid 50’s for the plains with mid to upper 40’s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will produce a 0.10”-0.40" total, in 10-30 minutes. A weak to moderate thunderstorm will produce 0.40-0.70” total, in 10-30 minutes. WORST CASE SCENARIO: An outflow boundary from storms east of Denver could initiate overnight thunderstorms across the District producing moderate to heavy rainfall up to 1.50” total in 45-60 minutes. A LOOK AHEAD: A better chance for showers/thunderstorms Thursday as a disturbance moves through the region. An uptick in overall moisture, combined with upper-level support will likely result in a chance for heavy rainfall Thursday. Similar conditions remain in place Friday, although upper-level shifts northwesterly, leading to slightly less chances for heavy rainfall as storms expected to increase in speed during the day and into the evening Friday. This weekend will remain fairly active with afternoon and evening showers/thunderstorm chances both Saturday and Sunday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Arapahoe Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Boulder Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Broomfield Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Denver Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Douglas Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Jefferson Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Foothills above 6500ft       Boulder Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Douglas Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) LOW Jefferson Current TO 1130 PM WED 0.1" (25%) to 0.4" (20%) to 0.7" (10%) 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]