Time: 812 AM Sun September 19, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- HOT, SUNNY AND DRY - Unseasonably warm temperatures today with highs reaching the mid 80's to around 90 this afternoon with upper 70's to low 80's along the foothills. - Winds will start to pick up late this evening as they shift from the north as a cold front moves in through the overnight. - Overnight will be breezy and cool with lows dropping into the upper 40's for the plains with low 40's for the foothills. Precipitation chances will also increase behind the cold front with a few isolated rain showers possible in the early morning hours Monday. STORM RAINFALL POTENTIAL AND DURATION: Typical overnight rain showers will produce a trace-0.10" in 10-30 minutes. A moderate rain shower could produce 0.1-0.3" in 10-30 minutes. WORST CASE SCENARIO: A stronger rain shower or training or rain showers has the potential to produce 0.3-0.8" in 60 minutes. A LOOK AHEAD: As the disturbance moves through the region Monday, off and on rain showers will be possible during the day and potentially an isolated thunderstorm in the afternoon, with the threat for heavy rainfall being minimal at best. Temperatures will be cooler on Monday with highs only reaching the upper 60's to low 70's. Cooler high temperatures remain Tuesday with dry conditions throughout the day. High-pressure returns Wednesday leading to warmer temperatures and continued dry conditions. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Arapahoe 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Boulder 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Broomfield 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Denver 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Douglas 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Jefferson 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Foothills above 6500ft       Boulder 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Douglas 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Jefferson 1100 PM TO 800 AM MON Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]