Time: 947 AM Mon August 12, 2024 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- Slightly cooler, scattered/numerous PM showers/t-storms The monsoonal moisture transport setup remains in place for Colorado and the District today, with potential for some of the heavier thunderstorm-driven rainfall of the year today and tomorrow. Morning dewpoints across the District are hovering around 60, and will mix down to the low/mid 50s by the time daytime heating initiates convection over the high country west of the District. Storms that make their way east into the foothills and plains of the District midafternoon will have 1.00"-1.15" of precipitable water (PWAT) to work with, and slower storm motions than the past few days will lead to an increased chance for message issuance and localized low impact flooding today. Hail and gusty outflow winds that reach severe thresholds will also be possible with stronger storms. Outflow boundary-driven storm initiation appears likely after the first round of storms today, with potential for lingering thunderstorms around the District remaining through the evening and into the night, though the indication is that the majority of this action will remain east of the District. Skies will eventually clear by midnight, giving way to overnight lows around 60. STORM RAINFALL POTENTIAL AND DURATION: Typical showers and thunderstorms will produce 0.25"-0.75" in 10-30 minutes. Stronger or slower moving thunderstorms will produce up to 1.50" total in 10-30 minutes. WORST CASE SCENARIO: An extremely strong/stationary thunderstorm, or training of thunderstorms along a boundary, may produce up to 2.50" total in 60 minutes or less. A LOOK AHEAD: Similar moisture and forcing will be present again tomorrow, and early indications are of another day of likely message issuance. Storm coverage will taper off slowly as the week goes on due to an approaching trough from the Pacific Northwest that will change the upper-level flow direction, cutting off monsoonal moisture transport. Residual moisture will still be enough, however, to initiate seasonal convection through the end of the work week. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Arapahoe 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Boulder 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Broomfield 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Denver 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Douglas 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Jefferson 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Foothills above 6500ft       Boulder 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Douglas 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH Jefferson 100 PM TO 1100 PM 0.3" (70%) to 0.8" (50%) to 1.5" (30%) HIGH MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]