Flash Flood Prediction Program

Time: 804 AM Fri August 19, 2022 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- WARM WITH A CHANCE FOR AFTERNOON RAIN SHOWERS/ISOLATED THUNDERSTORMS - Northwesterly upper-level flow aloft today will bring mild conditions early as high temperatures reach the low to mid 80's this afternoon. A weak disturbance moves through the region this afternoon bringing a chance for afternoon rain showers/isolated thunderstorms. - Storm chances today will be hit or miss for the most part with most areas coming in dry. However, a chance will remain for a few rain showers/isolated thunderstorms this afternoon with the best chance between 2-8pm. Storm motions should be fairly brisk, between 10-15mph from the NW to SE which should help limit point rainfall amounts, although a slight chance for a storm to form along an outflow boundary and produce a quick 0.5" in 10 minutes resulting in a LOW chance for Message 1 issuance this afternoon. - After 8pm, skies will gradually clear with mild conditions expected through the overnight. Lows will drop into the upper 50's to low 60's be daybreak Saturday. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will only produce a trace to 0.2" of rainfall in 10-30 minutes. A moderate rain shower/isolated thunderstorm could produce 0.2-0.5" in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm, or anchored rain shower/thunderstorm, likely formed off an outflow boundary has the potential to produce 0.5-1.5" in 60-90 minutes. A LOOK AHEAD: An active weather pattern will hold through the weekend with rain showers/thunderstorm chances both Saturday and Sunday. Saturday's storms will favor areas south and along the Palmer Divide at this time. Sunday will bring a better chance for widespread rainfall across the District with a better chance for moderate to brief heavy rainfall. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.5" (10%) LOW Arapahoe 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.5" (10%) LOW Boulder 200 PM TO 800 PM Trace (50%) to 0.2" (25%) to 0.5" (10%) LOW Broomfield 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.5" (10%) LOW Denver 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.5" (10%) LOW Douglas 200 PM TO 800 PM Trace (50%) to 0.2" (25%) to 0.5" (10%) LOW Jefferson 200 PM TO 800 PM Trace (50%) to 0.2" (25%) to 0.5" (10%) LOW Foothills above 6500ft       Boulder 200 PM TO 800 PM Trace (50%) to 0.2" (25%) to 0.5" (15%) LOW Douglas 200 PM TO 800 PM Trace (50%) to 0.2" (25%) to 0.5" (15%) LOW Jefferson 200 PM TO 800 PM Trace (50%) to 0.2" (25%) to 0.5" (15%) 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]