Flash Flood Prediction Program

Time: 848 AM Thu September 14, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- COOLER TODAY WITH A GOOD CHANCE FOR WIDESPREAD SHOWERS/THUNDERSTORMS THIS AFTERNOON AND EVENING Today a cold front will pass through the Front Range Urban Corridor bringing fall like temperatures and likely widespread rain. Highs this afternoon will be stunted, only reaching around 70 degrees for the plains with mid to upper 60s along the foothills. Cloud coverage will be scattered to broken this morning and will increase to overcast as the day progresses. Showers and thunderstorms will be likely today and tonight, with a few isolated showers and thunderstorms starting in the early afternoon and will increase in coverage becoming widespread between 6-7 PM. Chances of severe storms are very unlikely within the District as temperatures remain cool today, however, elevated available moisture will bring pockets of moderate to heavy rainfall which could potentially lead to some localized flooding under stronger storms. The peak timing for heavy rainfall will be between 4-10pm. Thunderstorm and heavy rainfall chances will likely dissipate by 9-10 PM with widespread light to moderate showers dominating the area and continuing through the overnight. Overnight lows will dip 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 0.10-0.40” total in 10-30 minutes. A moderate shower/thunderstorm will produce rainfall of 0.40 to 0.80” total in 10-30 minutes. WORST CASE SCENARIO: A strong shower/thunderstorm, or training of thunderstorms has the potential to produce 0.80” to 1.60” in under 60 minutes. A LOOK AHEAD: Cooler Friday, with off and on showers possible through the morning and possibly into the afternoon. High temperatures will reach the mid 60s in the afternoon with skies gradually clearing into the evening. Warmer Saturday as high temperatures reach the mid 70s under mostly sunny skies. High-pressure builds Sunday bringing high temperatures back to a more seasonable low 80s with continued sunny skies throughout the day. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 1000 PM 0.1" (80%) to 0.4" (60%) to 0.8" (30%) MOD Arapahoe 200 PM TO 1000 PM 0.1" (85%) to 0.4" (65%) to 0.8" (35%) MOD Boulder 200 PM TO 1000 PM 0.1" (80%) to 0.4" (60%) to 0.8" (30%) MOD Broomfield 200 PM TO 1000 PM 0.1" (80%) to 0.4" (60%) to 0.8" (30%) MOD Denver 200 PM TO 1000 PM 0.1" (80%) to 0.4" (60%) to 0.8" (30%) MOD Douglas 200 PM TO 1000 PM 0.1" (85%) to 0.4" (65%) to 0.8" (35%) MOD Jefferson 200 PM TO 1000 PM 0.1" (85%) to 0.4" (65%) to 0.8" (35%) MOD Foothills above 6500ft       Boulder 200 PM TO 1000 PM 0.1" (90%) to 0.4" (70%) to 0.8" (40%) MOD Douglas 200 PM TO 1000 PM 0.1" (90%) to 0.4" (70%) to 0.8" (40%) MOD Jefferson 200 PM TO 1000 PM 0.1" (90%) to 0.4" (70%) to 0.8" (40%) 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]