Flash Flood Prediction Program

Time: 1004 AM Tue May 21, 2024 Forecaster: Laura Smith ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- Another cool day with a chance for afternoon showers and isolated thunderstorms The springtime pattern continues across the Front Range Urban Corridor as another upper-level trough sweeps across the state today. Afternoon highs will reach the upper 50s to low 60s, dew points in the upper 30s to low 40s, and precipitable water (PWAT) values around 0.5”-0.6”. Chances for isolated showers and thunderstorms will gradually improve throughout the day, becoming scattered to widespread by the late afternoon. Storm motions will be from west to east around 20-25 mph. Storms will begin clearing after sunset, with precipitation fully concluding by the mid to late evening. STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce a trace to 0.25” total in 10-30 minutes. A moderate shower/thunderstorm will produce 0.25”-0.50” total in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm, or training of thunderstorm cells, will have the potential to produce 0.50” to 0.80” total in up to 60 minutes. A LOOK AHEAD: Warmer temperatures are expected Wednesday as sunny morning skies allow afternoon highs to reach the upper 60s to low 70s. Dewpoints will be in the upper 20s to low 30s, supporting slight chances for afternoon to evening showers and thunderstorms. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (90%) to 0.25" (60%) to 0.5" (30%) LOW Arapahoe 200 PM TO 800 PM Trace (90%) to 0.25" (60%) to 0.5" (30%) LOW Boulder 200 PM TO 800 PM Trace (80%) to 0.25" (40%) to 0.5" (20%) LOW Broomfield 200 PM TO 800 PM Trace (80%) to 0.25" (40%) to 0.5" (20%) LOW Denver 200 PM TO 800 PM Trace (90%) to 0.25" (60%) to 0.5" (30%) LOW Douglas 200 PM TO 800 PM Trace (80%) to 0.25" (40%) to 0.5" (20%) LOW Jefferson 200 PM TO 800 PM Trace (80%) to 0.25" (40%) to 0.5" (20%) LOW Foothills above 6500ft       Boulder 100 PM TO 800 PM Trace (80%) to 0.25" (40%) to 0.5" (20%) LOW Douglas 100 PM TO 800 PM Trace (80%) to 0.25" (40%) to 0.5" (20%) LOW Jefferson 100 PM TO 800 PM Trace (80%) to 0.25" (40%) 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]