Time: 838 AM Sat October 1, 2022 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ANOTHER CHANCE FOR STRONG AFTERNOON AND EARLY EVENING THUNDERSTORMS - The trough of low-pressure has stalled out resulting in little change to the overall pattern today with another good chance for a round or two of afternoon thunderstorms will last into the evening with rain showers likely persisting into the overnight once again. Due to this pattern, there will be a moderate chance for Message 1's to be issued for this afternoon. - The severity of storms today will hinge on whether or not we get sufficient daytime heating, however, with good upper-level support today, there will be a decent chance of seeing moderate to brief heavy rainfall between 2-8pm across the District with light to moderate rain showers through midnight and off and on light rain possible through daybreak Sunday. Storm motions will be from W to E between 5-10mph, with erratic storm motions possible off outflow boundaries which will also increase chances for brief heavy rainfall this afternoon. Some storms may also contain gusty winds 50+mph, hail up to 1" and frequent cloud to ground lightning. - Overnight rain showers should remain light, although, with good upper-level support through the overnight a few stronger storms can not be completely ruled out at this time, mainly through midnight. Overnight lows will drop into the mid 40's to around 50 degrees with partly to mostly cloudy skies. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers will produce a trace to 0.30" of rainfall in 10-30 minutes. moderate to strong thunderstorms will produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: An erratic, slow moving storm, or training of thunderstorm cells has the potential to produce 1.6" in 45-60 minutes. A LOOK AHEAD: This pattern holds at least through tomorrow with another chance for rain showers/thunderstorms Sunday afternoon and evening. Sufficient moisture aloft and at the surface will likely keep at least a low chance for moderate to brief heavy rainfall tomorrow. Will update tomorrow with another HPO if needed. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Arapahoe 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Boulder 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Broomfield 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Denver 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Douglas 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Jefferson 200 PM TO 900 PM Trace (80%) to 0.3" (50%) to 0.8" (25%) MOD Foothills above 6500ft       Boulder 200 PM TO 900 PM Trace (90%) to 0.3" (60%) to 0.8" (30%) MOD Douglas 200 PM TO 900 PM Trace (90%) to 0.3" (60%) to 0.8" (30%) MOD Jefferson 200 PM TO 900 PM Trace (90%) to 0.3" (60%) to 0.8" (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]