Flash Flood Prediction Program

Time: 850 AM Tue September 12, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- WARMER, SUNNY AND GENERALLY DRY Sunny and mild to start the day today with clouds increasing this afternoon. High temperatures will reach a more seasonable mid to upper 70s. Upper-level flow aloft remains northwesterly, keeping a very slight chance for a few showers and possibly a thunderstorm or two, mainly along the foothills and Palmer Divide. A shower could potentially move into the District with the best chance for any showers being between 1-8pm. Any shower activity will likely be limited to areas south of I-70. Skies will clear through the rest of the evening with mild and dry conditions expected through the overnight and into Wednesday. Overnight lows will drop into the low 50s for the plains with mid to upper 40s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce a trace to 0.10” total in 10-30 minutes. A moderate shower/thunderstorm will produce rainfall of 0.10 to 0.25” total in 10-30 minutes. WORST CASE SCENARIO: A strong shower/thunderstorm, or training of thunderstorms has the potential to produce 0.25” to 0.75” in under 60 minutes. A LOOK AHEAD: An increased chance for showers and thunderstorms tomorrow afternoon and early evening as high temperatures reach 80 degrees. A very slight chance for some isolated moderate to heavy rainfall, once again mainly along the foothills and Palmer Divide. An increase in overall moisture Thursday brings a good chance for showers/thunderstorms with a better chance for isolated moderate to heavy rainfall for portions of the District. Cooler temperatures Friday, in the low to mid 60s, will help limit storm activity, with off and on showers possible throughout the day and into the evening. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (10%) to 0.1" (5%) NONE Arapahoe 200 PM TO 800 PM Trace (15%) to 0.1" (10%) to 0.25" (5%) NONE Boulder 200 PM TO 800 PM Trace (10%) to 0.1" (5%) NONE Broomfield 200 PM TO 800 PM Trace (10%) to 0.1" (5%) NONE Denver 200 PM TO 800 PM Trace (15%) to 0.1" (10%) to 0.25" (5%) NONE Douglas 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.25" (5%) NONE Jefferson 200 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.25" (5%) NONE Foothills above 6500ft       Boulder 100 PM TO 800 PM Trace (15%) to 0.1" (10%) to 0.25" (5%) NONE Douglas 100 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.25" (5%) NONE Jefferson 100 PM TO 800 PM Trace (20%) to 0.1" (10%) to 0.25" (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]