Time: 926 AM Thu June 20, 2024 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- Warmer today with a good chance for afternoon and evening showers/thunderstorms. Southwesterly flow aloft, combined with clear skies this morning will heat the District well into the 80s if not around 90 degrees this afternoon. A disturbance will move into the region this afternoon, bringing a good chance for showers and thunderstorms across the I-25 corridor today, with multiple rounds possible into the evening hours with a few lingering showers possible overnight. Initial storm development will occur around midday today along the higher terrain, moving onto the foothills between 1-3pm with the best chance of thunderstorm activity in the District between 3-10pm with lingering showers through 2am at this time. The first round of showers and thunderstorms will have the biggest threat for moderate to heavy rainfall with localized flooding possible under stronger storm development. Storm motions will generally be WSW to ENE between 10-15mph, however, stronger storms will likely produce outflow boundaries resulting in some erratic storm movement. The largest threat today will likely be a quick 0.5” in 10-20min rather than any long-lasting rain. A few lingering showers and possibly a thunderstorm or two through the late evening with storms weakening overnight. Off and on weak showers will be possible overnight as temperatures drop into the low 60s along the plains with mid to upper 50s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce 0.05-0.25” total in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.25”-0.75” total in 10-30 minutes. WORST CASE SCENARIO: A strong stationary thunderstorm, or training of thunderstorms will have the potential to produce 1.50” in 30-60 minutes. A LOOK AHEAD: Similar conditions remain in place tomorrow as high temperatures reach the upper 80s to around 90 degrees. Another chance for afternoon showers and thunderstorms with at least a LOW chance for Message 1s to be issued. Conditions start to dry out Saturday as high temperatures reach well into the 90s. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 1000 PM 0.05" (80%) to 0.25" (60%) to 0.75" (30%) MOD Arapahoe 200 PM TO 1000 PM 0.05" (80%) to 0.25" (60%) to 0.75" (30%) MOD Boulder 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Broomfield 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Denver 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Douglas 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Jefferson 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Foothills above 6500ft       Boulder 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Douglas 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) MOD Jefferson 200 PM TO 1000 PM 0.05" (75%) to 0.25" (50%) to 0.75" (25%) 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]