Flash Flood Prediction Program

Time: 829 AM Thu May 25, 2023 Forecaster: Laura Smith ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ANOTHER ROUND OF SLOW-MOVING THUNDERSTORMS EXPECTED THIS AFTERNOON ACROSS THE DISTRICT A blocking pattern is in place over the continental US, positioning southwesterly upper-level flow across Colorado while low level moisture east of the Continental Divide remains heightened from yesterday's storms. High temperatures will reach the upper 70s to low 80s, dew points in the mid 40s to around 50°F, through the afternoon and evening. These conditions will support an unstable environment, favorable for thunderstorm development across the area by the mid to late afternoon. Forecast soundings reveal bulk shear around 30 kt, which will be sufficient for multicell clusters and slow southwesterly storm motions. Heavy rain may persist for an extended period of time with special emphasis on areas east of I-25 around the convergence zone. Storms are expected to dissipate by the late evening hours. STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms will produce a 0.25” to 0.75” in 10-30 minutes. A strong thunderstorm could produce 0.75” to 1.00” in 10-30 minutes. WORST CASE SCENARIO: Anchored or training thunderstorms have the potential to produce 1.00”-1.75” in 30-60 minutes. A LOOK AHEAD: Similar conditions are likely tomorrow as temperatures reach the upper 70s to low 80s followed by widely scattered afternoon to evening thunderstorms, with a potential for heavy rain once again. Looking ahead, the upper-level pattern remains in place through the weekend supporting high temperatures around 80°F and afternoon to evening showers and thunderstorms. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 400 PM TO 1000 PM 0.25" (75%) to 0.5" (50%) to 1" (25%) HIGH Arapahoe 400 PM TO 1000 PM 0.25" (90%) to 0.5" (60%) to 1" (25%) HIGH Boulder 400 PM TO 1000 PM 0.25" (75%) to 0.5" (50%) to 1" (15%) HIGH Broomfield 400 PM TO 1000 PM 0.25" (75%) to 0.5" (50%) to 1" (15%) HIGH Denver 400 PM TO 1000 PM 0.25" (75%) to 0.5" (50%) to 1" (25%) HIGH Douglas 400 PM TO 1000 PM 0.25" (90%) to 0.5" (60%) to 1" (25%) HIGH Jefferson 400 PM TO 1000 PM 0.25" (75%) to 0.5" (50%) to 1" (15%) HIGH Foothills above 6500ft       Boulder 300 PM TO 900 PM 0.25" (75%) to 0.5" (50%) to 1" (15%) HIGH Douglas 300 PM TO 900 PM 0.25" (90%) to 0.5" (60%) to 1" (25%) HIGH Jefferson 300 PM TO 900 PM 0.25" (90%) to 0.5" (60%) to 1" (25%) 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]