Time: 903 AM Sat July 22, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- WARMER TODAY WITH A VERY SLIGHT CHANCE FOR LATE EVENING SHOWERS/ISOLATED THUNDERSTORMS Very little change to the overall pattern today as strong northwesterly flow aloft hangs around northeastern Colorado today and into the evening. With these strong upper-level winds relatively close, there will be a very slight chance for storms to develop in and around the District today. Especially if storms to the east produce outflow boundaries that move into the District, similar to yesterday. Currently skies are clear with temperatures around 70 degrees, with highs expected to reach the upper 80’s to low 90’s this afternoon. Elevated dew points remain a concern with mid to upper 50’s currently east of I-25. If these dew points stick around throughout the day, with full sunshine through the afternoon, another risk of storms will be likely late this afternoon and into the evening. The best chance for storm development will be along the higher terrain foothills between 3-5pm and moving SE through the District between 5-10pm with skies clearing quickly behind and storm developmet. Once again storm movement will be fairly brisk, between 20-30mph which will help limit any point rainfall amounts if storms do develop within the District boundaries. The largest threat for any heavy rainfall will be a quick 0.5” in 10-15 minutes, resulting in a LOW chance for Message 1’s to be issued. Overnight will be mild and dry with lows dropping into the low 60’s on the plains with mid to upper 50’s for the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and thunderstorms will produce a TR-0.20” total, in 10-30 minutes. A moderate to strong thunderstorm will produce 0.20-0.50” total, in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm anchors off an outflow boundary, or training of thunderstorms could potentially produce up to 1.0” total in 45-60 minutes. A LOOK AHEAD: Drier air moves into the region tomorrow resulting in dry conditions throughout the day for the District. A few weak showers, maybe an isolated thunderstorm will be possible along the Palmer Divide. Similar conditions to start the day Monday with a slightly better chance of high-based showers thunderstorms with minimal if any precipitation as most struggles to reach the surface as temperatures reach nearly 100 degrees. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Arapahoe 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Boulder 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Broomfield 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Denver 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Douglas 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Jefferson 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Foothills above 6500ft       Boulder 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Douglas 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) LOW Jefferson 400 PM TO 1000 PM Trace (20%) to 0.2" (15%) to 0.5" (10%) 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]