Flash Flood Prediction Program

Time: 1039 AM Wed May 24, 2023 Forecaster: Laura Smith ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- SLOW-MOVING THUNDERSTORMS EXPECTED THIS AFTERNOON ACROSS THE DISTRICT High pressure ridging across the central US will amplify today as the next weather system drops into the Great Basin. This pattern will position southwesterly upper-level flow across Colorado while low level moisture builds east of the Continental Divide. High temperatures will reach the mid to upper 70s, dew points in the upper 40s to low 50s, 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 weak wind shear profiles, resulting in slow-moving westerly 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 45-60 minutes. A LOOK AHEAD: Similar conditions are likely tomorrow as temperatures reach the upper 70s to low 80s followed by widely scattered late 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 200 PM TO 800 PM 0.25" (75%) to 0.75" (50%) to 1" (25%) HIGH Arapahoe 200 PM TO 800 PM 0.25" (90%) to 0.75" (60%) to 1" (30%) HIGH Boulder 200 PM TO 800 PM 0.25" (75%) to 0.75" (50%) to 1" (25%) HIGH Broomfield 200 PM TO 800 PM 0.25" (75%) to 0.75" (50%) to 1" (25%) HIGH Denver 200 PM TO 800 PM 0.25" (75%) to 0.75" (50%) to 1" (25%) HIGH Douglas 200 PM TO 800 PM 0.25" (90%) to 0.75" (60%) to 1" (30%) HIGH Jefferson 200 PM TO 800 PM 0.25" (75%) to 0.75" (50%) to 1" (25%) HIGH Foothills above 6500ft       Boulder 100 PM TO 700 PM 0.25" (75%) to 0.75" (50%) to 1" (25%) HIGH Douglas 100 PM TO 700 PM 0.25" (90%) to 0.75" (60%) to 1" (30%) HIGH Jefferson 100 PM TO 700 PM 0.25" (90%) to 0.75" (60%) to 1" (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]