Flash Flood Prediction Program

Time: 852 AM Thu August 3, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- A CHANCE FOR AFTERNOON/EARLY EVENING SHOWERS/THUNDERSTORMS WITH BRIEF HEAVY RAINFALL Very minimal change to the overall pattern again today as westerly flow aloft continues to dominate over the region. Dew points have remained in the upper 50’s to around 60 and will likely only decrease slightly through the rest of the day. The best chance for storm development within the District will be between 2-8pm. Storm motions will once again be W to E between 10-20mph, effectively limiting any point rainfall amounts. However, a few storms could produce gust fronts, with additional storms forming along these gust fronts within the District. These storms will have the highest potential to produce impactful heavy rainfall as they will likely stall out over an area for an extended period. Currently only one round of showers and thunderstorms will move across the District through the afternoon and early evening, with the strongest storms likely during the afternoon with storms decreasing in intensity as the evening progresses over the District. A better chance for stronger storm development just east of the District and onto the eastern plains where severe weather will be likely through the late evening hours. Skies will clear this evening after 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 0.05-0.25” total, in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.25-0.75” total in 10-30 minutes. Strong thunderstorms will produce 0.75-1.25” total in 10-30 minutes. WORST CASE SCENARIO: A stronger, stalled out thunderstorm is able to develop and will have the potential to produce up to 2.00” total, in 45-60 minutes. A LOOK AHEAD: An overall decrease in moisture in the area tomorrow will likely limit the heavy rainfall threat significantly. Storm chances will be similar to today, between 2-8pm with west to east storm movements between 15-25mph which will help limit point rainfall amounts. Storms will generally be weaker than previous days, at least over the District both Friday and Saturday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM 0.05" (70%) to 0.25" (40%) to 0.75" (20%) MOD Arapahoe 200 PM TO 800 PM 0.05" (70%) to 0.25" (40%) to 0.75" (20%) MOD Boulder 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Broomfield 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Denver 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Douglas 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Jefferson 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Foothills above 6500ft       Boulder 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Douglas 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) MOD Jefferson 200 PM TO 800 PM 0.05" (60%) to 0.25" (30%) to 0.75" (15%) 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]