Flash Flood Prediction Program

Time: 841 AM Mon August 23, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- HOT TODAY WITH A SLIGHT CHANCE FOR HIGH-BASED AFTERNOON RAIN SHOWERS/ISOLATED THUNDERSTORMS - Above average temperatures continue over the District today as highs reach the low 90's on the plains with low to mid 80's along the foothills. Mild with mostly sunny skies this morning with a slight chance for scattered high-based rain showers/isolated thunderstorms this afternoon and early evening. - Rain showers and thunderstorms will initiate in the high country around midday with the best chance for storms in the District between 1-8pm this afternoon and early evening. Currently dew points are in the mid 40's to around 50 and will likely mix out through the day into the mid to upper 30's this afternoon. With such a wide temperature/dew point spread, the biggest threat today from any storms that develop will be gusty winds and possibly a few lightning strikes. Rainfall will likely be minimal at this time, however, if dew points do not mix out and they remain elevated, the threat for moderate to very brief heavy rainfall could increase this afternoon and early evening. - After sunset skies will gradually clear leading to mild and dry conditions through the overnight with lows dropping into the upper 50's to low 60's on the plains with low 50's along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical high-based rain showers will produce a trace to 0.10" of rainfall in 10-30 minutes. An isolated thunderstorm will produce 0.1-0.3" of rainfall in 10-30 minutes. WORST CASE SCENARIO: A moderate to strong thunderstorms has the potential to produce 0.3-0.8" of rainfall in 45-60 minutes. A LOOK AHEAD: Conditions rapidly dry out tomorrow as high temperatures reach the low to mid 90's during the afternoon under mostly sunny skies. Similar conditions Wednesday with another slight chance for scattered high-based rain showers/isolated thunderstorms. A shift in the pattern towards the end of the week and heading into the weekend with storm chances picking up with the threat for stronger afternoon/evening storm development along with at least a low heavy rainfall both Thursday and Friday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Arapahoe 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Boulder 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Broomfield 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Denver 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Douglas 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Jefferson 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.3" (5%) NONE Foothills above 6500ft       Boulder 100 PM TO 700 PM Trace (30%) to 0.1" (20%) to 0.3" (10%) NONE Douglas 100 PM TO 700 PM Trace (30%) to 0.1" (20%) to 0.3" (10%) NONE Jefferson 100 PM TO 700 PM Trace (30%) to 0.1" (20%) to 0.3" (10%) 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]