Time: 936 AM Wed August 3, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- THUNDERSTORMS WILL FAVOR THE FOOTHILLS AND PALMER DIVIDE WEST AND SOUTH OF THE DISTRICT - Temperatures will be cooler today behind last evenings cold front with highs topping out in the upper 80's to lower 90's over the plains with 70's and 80's in the Front Range foothills. Normal high for Denver today is 89 degrees. Surface moisture has increased behind the front but the thunderstorms today will favor the foothills and Palmer Divide W and S of the District as the air over the plains will be more stable with cooler temperatures and a warm layer of air aloft between 450-500 millibars or between 20,000-22,000ft. - There will still be a chance for thunderstorms over the plains but they will be isolated at best with many areas on the dry side today. Thunderstorms over the foothills and Palmer Divide will have moisture to work with and some storms may produce brief heavy rainfall making for a fine line today between where storms are expected to fire and where there will be less activity. Overall, minimal storm activity is expected but the storms that do form may become moderate to strong over the higher terrain. - Best chances for storms today will be over the foothills outside the District between 1-9pm with slight chances plains between 3-9pm, favoring I-70 south if a storm is observed. Storms will move from WNW to ESE at 20-25mph weakening as they encounter the more stable air on the plains. Should the stable layer erode as the day progresses thunderstorm chances will increase lower elevations and an HPO update may be needed. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3". Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: Warm layer of air aloft erodes allowing for stronger storms over the plains with the potential to produce brief heavy rainfall of 0.4-1.2" in 10-30 minutes and up to 1.8" in 60 minutes. A LOOK AHEAD: Isolated to widely scattered thunderstorms are expected on Thursday with better chances for storms over the plains. Temperatures will warm back into the 90's. Friday will also feature isolated to widely scattered storms but the weekend is looking quite active as monsoon moisture moves overhead with thunderstorms capable of producing heavy rainfall. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 900 PM Trace (40%) to 0.3" (20%) to 0.9" (5%) NONE Arapahoe 300 PM TO 900 PM Trace (40%) to 0.3" (20%) to 0.9" (5%) NONE Broomfield 300 PM TO 900 PM Trace (40%) to 0.3" (20%) to 0.9" (5%) NONE Denver 300 PM TO 900 PM Trace (40%) to 0.3" (20%) to 0.9" (5%) NONE Boulder 200 PM TO 900 PM Trace (40%) to 0.3" (20%) to 0.9" (5%) NONE Douglas 200 PM TO 900 PM Trace (65%) to 0.3" (30%) to 0.9" (10%) LOW Jefferson 200 PM TO 900 PM Trace (50%) to 0.3" (25%) to 0.9" (5%) LOW Foothills above 6500ft       Boulder 300 PM TO 900 PM Trace (65%) to 0.3" (30%) to 0.9" (10%) LOW Douglas 300 PM TO 900 PM Trace (80%) to 0.3" (40%) to 0.9" (20%) LOW Jefferson 300 PM TO 900 PM Trace (75%) to 0.3" (40%) to 0.9" (15%) 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]