Time: 907 AM Sun August 21, 2022 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- SLIGHTLY WARMER TODAY WITH ANOTHER CHANCE FOR AFTERNOON/EVE SHOWERS/THUNDERSTORMS - Not much change to the overall pattern today as another good chance for afternoon/evening rain showers/thunderstorms with isolated heavy rainfall likely. Slightly warmer temperatures today in the upper 70's to low 80's should result in more widespread rain shower/thunderstorm chances across the District this afternoon and evening. - Storm will likely initiate along the higher terrain by midday with the best chance for storms in the District between 1-9pm. Storm movements will be slow to non-existent, which will increase the threat for moderate to heavy rainfall today. Storms could also behave similar to yesterday where they pulse up and down, triggering additional storms along the flanking outflow boundaries. This will also increase the threat for moderate to heavy rainfall through the afternoon and evening. - The largest threat for heavy rainfall will be a quick 0.5" in 10-15 minutes, however, with the threat for anchored storms today, good surface moisture, combined with decent upper-level support will have the potential for isolated areas to break over 1" of rainfall in 10-30 minutes. Rainfall chances will continue through 9 or 10pm before tapering off for the evening. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will only produce 0.1"-0.5" of rainfall in 10-30 minutes. A moderate to strong rain shower/thunderstorm could produce 0.5-1.0" in 10-30 minutes. WORST CASE SCENARIO: A strong anchored rain shower/thunderstorm, or training of rain showers/thunderstorms have the potential to produce 1.0-2.5" in 45-60 minutes. A LOOK AHEAD: Warmer and a little more dry heading into next week as Monday's high temperatures reach the low to mid 80's. A slight chance will remain for afternoon rain showers/isolated thunderstorms, however the threat for moderate to brief heavy rain will be minimal at best. Conditions dry out even more Tuesday with highs will into the 80's with a very slight chance for a few high-based afternoon rain showers/isolated thunderstorms. Mid to upper 80's Wednesday with a continued slight chance for high based rain showers/isolated thunderstorms in the afternoon and early evening. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 1000 PM 0.1" (60%) to 0.5" (40%) to 1.0" (20%) HIGH Arapahoe 200 PM TO 1000 PM 0.1" (60%) to 0.5" (40%) to 1.0" (20%) HIGH Boulder 200 PM TO 1000 PM 0.1" (60%) to 0.5" (40%) to 1.0" (20%) HIGH Broomfield 200 PM TO 1000 PM 0.1" (75%) to 0.5" (50%) to 1.0" (25%) HIGH Denver 200 PM TO 1000 PM 0.1" (60%) to 0.5" (40%) to 1.0" (20%) HIGH Douglas 200 PM TO 1000 PM 0.1" (75%) to 0.5" (50%) to 1.0" (25%) HIGH Jefferson 200 PM TO 1000 PM 0.1" (75%) to 0.5" (50%) to 1.0" (25%) HIGH Foothills above 6500ft       Boulder 200 PM TO 1000 PM 0.1" (70%) to 0.5" (45%) to 1.0" (20%) HIGH Douglas 200 PM TO 1000 PM 0.1" (75%) to 0.5" (50%) to 1.0" (25%) HIGH Jefferson 200 PM TO 1000 PM 0.1" (75%) to 0.5" (50%) to 1.0" (25%) HIGH MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]