Flash Flood Prediction Program

Time: 949 AM Sat September 11, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- RECORD BREAKING HEAT OVER THE PLAINS WITH ISOLATED AFTERNOON TO EVENING STORMS POSSIBLE - Another hot day with at or above record breaking temperatures with afternoon highs expected to reach the low to mid 90's. Current record at DIA is 93 degrees which was set in 2018. - A slight chance for showers and thunderstorms this afternoon and through the evening hours ahead of tonight’s cool front. Very little available moisture will limit precipitation today, with any high-based isolated rain showers or thunderstorms expected to mainly produce gusty winds. - Overnight will be mild with lows dropping into the upper 50's to low 60's for the plains with upper 40's to low 50's along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical isolated rain showers/thunderstorms will produce a TR-0.10" in 10-30 minutes. A moderate thunderstorm potential to produce 0.1-0.2" in 10- 30 minutes. WORST CASE SCENARIO: A strong thunderstorm, or training of rain showers has the potential to produce 0.2-0.5" in 30-60 minutes. A LOOK AHEAD: A welcomed cool front will sweep across the state tonight, offering some relief from the exceptional heat. On Sunday, high temperatures are expected to reach the mid 80’s with another round of afternoon to evening isolated showers and thunderstorms. The cool front will also displace lingering wildfire smoke through the weekend, but smoke conditions are expected to worsen once again early next week as upper-level flow across the intermountain west becomes more zonal. On Monday, temperatures will warm into the upper 80’s to low 90’s with afternoon to evening thunderstorms ahead of another cool front Monday night. Tuesday is expected to be stormy with scattered showers and thunderstorms across the Front Range Urban Corridor, and temperatures reaching the mid 70’s. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Arapahoe 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Boulder 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Broomfield 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Denver 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Douglas 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Jefferson 100 PM TO 700 PM Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Foothills above 6500ft       Boulder 100 PM TO 700 PM Trace (30%) to 0.1" (15%) to 0.2" (5%) NONE Douglas 100 PM TO 700 PM Trace (30%) to 0.1" (15%) to 0.2" (5%) NONE Jefferson 100 PM TO 700 PM Trace (30%) to 0.1" (15%) to 0.2" (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]