Time: 1010 AM Thu August 4, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- NEAR RECORD HEAT WITH ISOLATED AFTERNOON THUNDERSTORMS - Ridge of high pressure aloft will strengthen today resulting in near record heat over the District. Temperatures will warm into the mid to upper 90's over the plains with 80's in the Front Range foothills. Normal high for Denver today is 89 degrees and the record is 98 which may be tied but is not expected to be broken. - The best chances for storms will “horseshoe” around the majority of the District as the foothills and Palmer Divide to the W and S will have a better chance for storms and a surface wind convergence line set up to the E may fire storms over the plains. All this equates to a low chance for isolated storms most areas, generally producing light to briefly moderate rainfall and gusty winds but a stronger storm cannot be ruled out. Typical storms will move from W to E at 10-15mph. - Moisture levels are modest and storm motions relatively slow resulting in the storms that do form around the District over the foothills and Palmer Divide having the potential to produce moderate to heavy rainfall. Best chances for storms will be between 2-8pm over the foothills and Palmer Divide and between 3-8pm plains. Should storms outside the District produce rain cooled outflow boundaries it may act as a trigger for storms in areas where it is not expected currently resulting in a LOW to MODERATE Message potential. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3" of rain. Moderate to possibly strong thunderstorms will have the potential to produce 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: Surface moisture increases further than expected due to thunderstorm outflow boundaries outside the District resulting in strong/slow moving thunderstorms with the potential to produce rainfall rates of 0.5-1.3" in 10-30 minutes and up to 2.0" in 60 minutes. A LOOK AHEAD: Another HOT day on Friday with temperatures in the mid to upper 90's. Thunderstorm activity is expected to increase with widely scattered storms leading to some relief from the heat in the later afternoon as clouds build and storms form. Monsoon moisture will move overhead on Saturday and result in scattered to numerous thunderstorms with the potential to produce heavy rainfall that may lead to excessive runoff and possibly flash flooding. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 800 PM Trace (50%) to 0.3" (25%) to 0.9" (5%) LOW Arapahoe 300 PM TO 800 PM Trace (65%) to 0.3" (30%) to 0.9" (5%) LOW Boulder 300 PM TO 800 PM Trace (50%) to 0.3" (25%) to 0.9" (5%) LOW Broomfield 300 PM TO 800 PM Trace (50%) to 0.3" (25%) to 0.9" (5%) LOW Denver 300 PM TO 800 PM Trace (50%) to 0.3" (25%) to 0.9" (5%) LOW Douglas 300 PM TO 800 PM Trace (75%) to 0.3" (40%) to 0.9" (10%) LOW Jefferson 300 PM TO 800 PM Trace (65%) to 0.3" (30%) to 0.9" (5%) LOW Foothills above 6500ft       Boulder 200 PM TO 800 PM Trace (75%) to 0.3" (40%) to 0.9" (10%) LOW Douglas 200 PM TO 800 PM Trace (90%) to 0.3" (60%) to 0.9" (30%) MOD Jefferson 200 PM TO 800 PM Trace (80%) to 0.3" (50%) to 0.9" (20%) MOD MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]