Flash Flood Prediction Program

Time: 514 PM Sat July 1, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- SLIGHTLY STRONGER UPPER-LEVEL DISTURBANCE HAS RESULTED IN BETTER STORM DEVELOPMENT AREAS NORTH An upper-level disturbance has started to move across the region at this time. Showers and weak thunderstorms have formed in Larimer & Boulder Counties and will continue southeast and through the District over the next few hours. The Best chance for shower/isolated thunderstorm activity will be from now through 9pm with a few linger showers possible into the late evening. Most if not all shower activity has diminished rapidly as it moves off the foothills. However, elevated surface dew points in the low 50’s will bring a LOW chance Message 1’s will have to be issued this evening. Storms are not expected to be particularly strong inside the District, but a gust front from a moderate thunderstorm outside of the District will have the potential for stronger storm development if that gust front ends up moving into the District. Skies will gradually clear after midnight with mild conditions expected through the overnight and into Sunday. Overnight lows will be in the mid to upper 50's. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers/isolated thunderstorms will produce trace-0.20” total, in 10-30 minutes. A moderate thunderstorm could produce 0.20-0.50” total, in 10-30 minutes. WORST CASE SCENARIO: A slower moving moderate thunderstorm, or training of thunderstorm cells has the potential to produce up to 1.0" in 45-60 minutes. A LOOK AHEAD: Similar conditions remain in place tomorrow with another chance for afternoon and early evening showers/isolated thunderstorms. Warmer tomorrow with highs expected in the mid to upper 80’s. Warmer and likely dry Monday with highs back in the low 90’s. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 900 PM SAT Trace (30%) to 0.2" (15%) to 0.5" (10%) LOW Arapahoe Current TO 900 PM SAT Trace (30%) to 0.2" (15%) to 0.5" (10%) LOW Boulder Current TO 900 PM SAT Trace (50%) to 0.2" (40%) to 0.5" (15%) LOW Broomfield Current TO 900 PM SAT Trace (30%) to 0.2" (15%) to 0.5" (10%) LOW Denver Current TO 900 PM SAT Trace (30%) to 0.2" (15%) to 0.5" (10%) LOW Douglas Current TO 900 PM SAT Trace (30%) to 0.2" (15%) to 0.5" (10%) LOW Jefferson Current TO 900 PM SAT Trace (50%) to 0.2" (40%) to 0.5" (15%) LOW Foothills above 6500ft       Boulder Current TO 900 PM SAT Trace (60%) to 0.2" (30%) to 0.5" (20%) LOW Douglas Current TO 900 PM SAT Trace (30%) to 0.2" (15%) to 0.5" (10%) LOW Jefferson Current TO 900 PM SAT Trace (60%) to 0.2" (30%) to 0.5" (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]