Time: 902 AM Tue July 18, 2023 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- HIGH BASED AFTERNOON/EVENING SHOWERS/THUNDERSTORMS PRODUCING MINIMAL RAIN AND GUSTY WINDS Temperatures will back off a few degrees from yesterday’s highs with readings in the low to mid 90’s over the plains and 80’s in the Front Range foothills. Normal high for Denver today is 91 degrees. Skies will start out mostly sunny and become partly to mostly cloudy this afternoon and evening. Mid and upper level moisture will increase today but surface moisture will be lacking resulting in high-based afternoon/evening showers and weak thunderstorms producing minimal rainfall and gusty winds of 30-40mph or more. Most storms today will produce just sprinkles or brief light rain, no heavy rainfall is expected. Shower and thunderstorm coverage is expected to be isolated over the plains with widely scattered storms over the foothills and Palmer Divide to the W and S of the District. Best chances for showers and weak thunderstorms will be from 3-10pm but may linger through midnight before drying out for the overnight period. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.2" of rain in 10-30 minutes. WORST CASE SCENARIO: A moderate thunderstorm is able to develop over the higher terrain producing rainfall rates of 0.1-0.4" in 10-30 minutes. A LOOK AHEAD: A cool front will move through on Wednesday and temperatures will be closer to normal at around 90 degrees. Moisture will begin to increase, and thunderstorms will be more likely in the afternoon and evening with widely scattered storms. Some storms may produce brief moderate/heavy rain and possibly hail. Thunderstorm activity looks to peak on Thursday with scattered to numerous showers and thunderstorms in the afternoon and evening. Thunderstorms will be capable of producing heavy rainfall and possibly severe weather. Highs Thursday will only reach the lower 80s. Remaining on the cooler side Friday with decreasing chances for thunderstorms. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 1100 PM Trace (60%) to 0.1" (30%) to 0.2" (15%) NONE Arapahoe 300 PM TO 1100 PM Trace (60%) to 0.1" (30%) to 0.2" (15%) NONE Boulder 300 PM TO 1100 PM Trace (65%) to 0.1" (30%) to 0.2" (15%) NONE Broomfield 300 PM TO 1100 PM Trace (60%) to 0.1" (30%) to 0.2" (15%) NONE Denver 300 PM TO 1100 PM Trace (60%) to 0.1" (30%) to 0.2" (15%) NONE Douglas 300 PM TO 1100 PM Trace (70%) to 0.1" (35%) to 0.2" (15%) NONE Jefferson 300 PM TO 1100 PM Trace (75%) to 0.1" (40%) to 0.2" (20%) NONE Foothills above 6500ft       Boulder 200 PM TO 1100 PM Trace (80%) to 0.1" (50%) to 0.2" (25%) NONE Douglas 200 PM TO 1100 PM Trace (90%) to 0.1" (60%) to 0.2" (30%) NONE Jefferson 200 PM TO 1100 PM Trace (90%) to 0.1" (60%) to 0.2" (30%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]