Time: 1008 AM Wed June 19, 2024 Forecaster: Laura Smith ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- Cooler today with slight chances for afternoon and evening activity Southeasterly surface flow throughout the day today will be responsible for the delivery of significant tropical moisture into the Colorado region, setting up the active weather pattern for the next few days along the Front Range urban corridor. After the passage of yesterday’s cold front, temperatures remain cool today, peaking in the low 70s. Dewpoints will be in the upper 40s to low 50s, with precipitable water (PWAT) values around 0.80”. There are a few limiting factors with storm development today that will restrict thunderstorm intensity: a lack of upper-level forcing, and cooler surface temps inhibiting convective initiation. If morning cloud cover remains throughout the afternoon, storm distribution and intensity will remain modest at best. If cloud cover dissipates, the area will receive enough heat for scattered convection capable of producing moderate to briefly heavy rainfall. Thunderstorms are expected to develop over the mountains by midafternoon, drifting over District just before the evening commute. Storm motions will be from southwest to northeast around 20 mph. Outflow boundary-driven initiation is likely throughout the evening and into the night, with isolated overnight showers possible. STORM RAINFALL POTENTIAL AND DURATION: Thunderstorms today have the potential to produce a trace to 0.50” in 10-30 minutes. WORST CASE SCENARIO: Strong thunderstorms may be capable of producing up to 1.25” in 30-60 minutes. A LOOK AHEAD: Storm uncertainty disappears tomorrow, as more Gulf moisture is transported into the region as the east coast heat wave intensifies. The outer edge of this heat wave will encourage temperatures well into the upper 80s and low 90s. A passing shortwave aloft will be responsible for thunderstorm development during the late afternoon, with severe threats possible: gusty winds up to 60+ mph, heavy localized rainfall, and one inch hail. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Arapahoe 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Boulder 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Broomfield 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Denver 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Douglas 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Jefferson 300 PM TO 900 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Foothills above 6500ft       Boulder 200 PM TO 800 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Douglas 200 PM TO 800 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW Jefferson 200 PM TO 800 PM Trace (70%) to 0.25" (50%) to 0.5" (20%) LOW MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]