Flash Flood Prediction Program

Time: 844 AM Mon June 5, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- WARMER TODAY WITH A MORE LATE SPRING LIKE WEATHER PATTERN IN PLACE A much more typical late spring day with partly cloudy skies this morning with the usual afternoon and evening rain shower/isolated thunderstorm chances. Excess moisture still at the surface, combined with adequate daytime heating will at least keep a MOD chance for Message 1’s to be issued this afternoon and into the evening. Dew points are currently in the low to mid 50’s and will likely hold throughout the day. A few showers/thunderstorms will build along the higher terrain by midday with storms slowly moving onto the plains this afternoon and into this evening. Fairly weak steering winds aloft signal relatively slow storm motions from west to east, which will also increase chances for longer lasting moderate to heavy rainfall today, especailly for areas west of I-25, where storms will likley anchor in place along the foothills. The best chance for impactful rain will be between 1-8pm with lingering showers possible into the late evening. With an already saturatued surface, it will not take much moderate or heavy rainfall to induce LOW IMPACT FLOODING today with pockets of standing water likley with any rainfall that does develop across the District. Also keep and eye on any streams or creeks rising throughout the day as good rainfall will be possible upstream, along the foothills by midday and into the afternoon. Overnight will gradually clear out as overnight lows expected in the low 50’s on the plains with mid to upper 40’s along the foothills. Skies will likely clear tomorrow morning with mostly sunny skies to start the day Tuesday. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and isolated thundestorms will produce 0.1-0.3” in 10-30 minutes. A moderate to strong thunderstorm could produce 0.3-0.7” in 10-30 minutes. WORST CASE SCENARIO: A stalled moderate to strong thunderstorm, or a thunderstorm that anchors off an outflow boundary will have the potential to produce up to 2.0” in under 60 minutes. A LOOK AHEAD: Much of the same tomorrow with another good chance for afternoon and early evening showers/thunderstorms with another MOD chacne for heavy rainfall as increase surface moisture holds over the region throughout the week. Wednesday rain chances pick up with widespread rain/thunderstorms possible in the afternoon and evening with localized flooding likely into the late evening hours. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.7" (15%) MOD Arapahoe 100 PM TO 800 PM 0.1" (60%) to 0.3" (30%) to 0.7" (15%) MOD Boulder 100 PM TO 800 PM 0.1" (80%) to 0.3" (40%) to 0.7" (25%) MOD Broomfield 100 PM TO 800 PM 0.1" (80%) to 0.3" (40%) to 0.7" (20%) MOD Denver 100 PM TO 800 PM 0.1" (70%) to 0.3" (35%) to 0.7" (15%) MOD Douglas 100 PM TO 800 PM 0.1" (70%) to 0.3" (35%) to 0.7" (15%) MOD Jefferson 100 PM TO 800 PM 0.1" (80%) to 0.3" (40%) to 0.7" (25%) MOD Foothills above 6500ft       Boulder 100 PM TO 800 PM 0.1" (90%) to 0.3" (60%) to 0.7" (30%) MOD Douglas 100 PM TO 800 PM 0.1" (90%) to 0.3" (60%) to 0.7" (30%) MOD Jefferson 100 PM TO 800 PM 0.1" (90%) to 0.3" (60%) to 0.7" (30%) 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]