Flash Flood Prediction Program

Time: 830 AM Sat June 3, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- CLOUDY AND COOL WITH SHOWERS PICKING UP THIS AFTERNOON AND EVENING Cloudy and cool currently with off and on rain showers expected across the District this morning. Showers will likely pick up this afternoon and into this evening with a good chance for moderate to heavy rainfall. The best chance for impactful rainfall will be around midday through 8pm when daytime heating is at its peak. However, daytime temperatures today are only going to reach the low 60’s resulting in mostly rain showers with a minimal chance for any isolated thunderstorms this afternoon and evening. Due to these cooler temperatures, the most likely threat will be rainfall rates exceeding 1” per hour, rather than the typical, convective, 0.5” in 10-15 minutes. IF temperatures increase today, resulting in an isolated thunderstorm or two, the chance for a quick 0.5” in 10-15 minutes will increase significantly as an abundance of available moisture is in the region. That being said, the District will have very efficient rainfall producing storms over the region for the next few days. Storm motions will also be atypical, with east to west motions, with some storms likely stalling out for extended periods over portions of the District. Rain showers are expected to continue into the evening, with at least a LOW threat of heavy rainfall throughout the overnight and into Sunday. Overnight temperatures will not drop too low with the cloud cover remaining in place with lows expected in the mid 50’s on the plains with around 50 for the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will produce 0.2-0.6” in 30-60 minutes. A moderate to heavy rain shower, or thunderstorm could produce 0.6-1.2” in 30-60 minutes. WORST CASE SCENARIO: An anchored thunderstorm, or training of moderate to heavy showers has the potential to produce up to 2.4” in 60 minutes. A LOOK AHEAD: This pattern will continue over the next few days, with widespread rain showers likely off and on Sunday morning, once again picking up into the afternoon and evening. Due to today’s rainfall, there will be a good chance for Messages to be issued tomorrow with the threat for heavy rainfall continuing through Monday. LOCATION PRIME TIME 60-Minute Rainfall and % Probability Message Potential Plains       Adams 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Arapahoe 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Boulder 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Broomfield 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Denver 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Douglas 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Jefferson 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Foothills above 6500ft       Boulder 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Douglas 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) MOD Jefferson 1100 AM TO 1159 PM 0.2" (100%) to 0.6" (75%) to 1.2" (50%) 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]