Flash Flood Prediction Program

Time: 819 AM Sat June 19, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- WARM TODAY WITH A GOOD CHANCE FOR AFTERNOON/EARLY EVENING RAIN SHOWERS/ISOLATED THUNDERSTORMS - An active weather pattern is in place this weekend with a good chance for afternoon rain/isolated thunderstorms this afternoon. Currently temperatures are in the upper 60's to low 70's and will reach around 90 degrees for highs today. A disturbance will move through the region this afternoon resulting in good chance for rain showers/isolated thunderstorms with a moderate chance for severe thunderstorms with brief heavy rain, gusty winds and hail around 1" in diameter. - Storms will initiate over the higher terrain after noon today with the best chance for storms across the District between 2-8pm with a few scattered rain/isolated thunderstorms possible after 8pm, favoring north and eastern portions of the District. Storm motions will be from the W/NW to E/SE between 10-20mph which will help limit point rainfall amounts, however a storm developing off an outflow boundary will have the potential to produce moderate to brief heavy rainfall today. - Skies will gradually clear later in the evening with overnight lows dropping into the low to mid 60's for the plains with upper 50's to around 60 along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and weak thunderstorms will produce a trace to 0.3" of rain. Moderate to strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: An anchored thunderstorm, or training of thunderstorm cells may result in up to 1.5" of rainfall in 45-60 minutes. A LOOK AHEAD: A break in storm activity during the day Sunday before a strong low-pressure system moves in from the north bringing a better chance for widespread moderate to heavy rainfall Sunday evening with a chance for lingering rain showers through the overnight and into Monday morning. Monday will be much cooler with high temperatures not making it out of the 70's with partly cloudy skies throughout the day. A slight chance Monday afternoon for additional rain showers or an isolated thunderstorms, although the threat for heavy rainfall remains minimal at this time. High-pressure quickly returns Tuesday as high temperatures jump back into the 90's with dry conditions expected throughout the day. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Arapahoe 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Boulder 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Broomfield 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Denver 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Douglas 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Jefferson 200 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.8" (20%) MOD Foothills above 6500ft       Boulder 200 PM TO 800 PM 0.1" (60%) to 0.3" (25%) to 0.8" (15%) MOD Douglas 200 PM TO 800 PM 0.1" (60%) to 0.3" (25%) to 0.8" (15%) MOD Jefferson 200 PM TO 800 PM 0.1" (60%) to 0.3" (25%) to 0.8" (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]