Time: 900 AM Fri August 4, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- A SLIGHT CHANCE FOR SHOWERS/ISOLATED THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING, MAINLY NORTH AND EAST OF THE DISTRICT. Not much change to the overall pattern once again today as westerly flow aloft continues to dominate over the region. Slightly less moisture aloft should decrease storm chances today, however, dew points have remained in the upper 50’s to around 60 and will likely only decrease slightly through the rest of the day. This will result in a LOW chance for Message 1’s as the potential for a quick 0.5” in 10-30 minutes remains today. Any storm development should stay to the north and move well east of the District. There will be a slight chance storms are able to develop in the District, especially if a gust front approaches from storms on the peripheral of the District. The best chance for storm development within the District will be between 2-8pm. Storm motions will be brisk from W to E between 15-25mph, effectively limiting any point rainfall amounts for storms that do develop. Skies will clear this evening, at or before sunset, with overnight lows in the upper 50’s to low 60’s on the plains with low to mid 50’s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers/weak thunderstorms will produce a 0.05-0.30” total, in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.30-0.60” total in 10-30 minutes. WORST CASE SCENARIO: A stronger, stalled out thunderstorm formed along an outflow boundary is able to develop, will have the potential to produce up to 1.20” total, in under 60 minutes. A LOOK AHEAD: A slightly better chance for storms Saturday afternoon and evening, with more widespread rainfall likely across the I-25 corridor. No doubt dew points will remain elevated, resulting in a chance for isolated heavy rainfall which will keep at least a LOW if not MOD chance for Message 1’s to be issued. Cooler temperatures Sunday behind a cold front will dictate the strength of storms, although there will be a good chance once again for widespread showers and possibly a few thunderstorms Sunday afternoon and evening. An uptick in overall moisture will likely bring a chance for moderate to heavy rainfall throughout most of the day Sunday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 800 PM FRI 0.05" (40%) to 0.25" (25%) to 0.6" (10%) LOW Arapahoe Current TO 800 PM FRI 0.05" (40%) to 0.25" (25%) to 0.6" (10%) LOW Boulder Current TO 800 PM FRI 0.05" (30%) to 0.25" (20%) to 0.6" (10%) LOW Broomfield Current TO 800 PM FRI 0.05" (30%) to 0.25" (20%) to 0.6" (10%) LOW Denver Current TO 800 PM FRI 0.05" (30%) to 0.25" (20%) to 0.6" (10%) LOW Douglas Current TO 800 PM FRI 0.05" (30%) to 0.25" (20%) to 0.6" (10%) LOW Jefferson Current TO 800 PM FRI 0.05" (30%) to 0.25" (20%) to 0.6" (10%) LOW Foothills above 6500ft       Boulder Current TO 800 PM FRI 0.05" (40%) to 0.25" (25%) to 0.6" (10%) LOW Douglas Current TO 800 PM FRI 0.05" (40%) to 0.25" (25%) to 0.6" (10%) LOW Jefferson Current TO 800 PM FRI 0.05" (40%) to 0.25" (25%) to 0.6" (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]