Time: 931 AM Sat July 29, 2023 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- CONTINUED HOT WITH ISOLATED TO WIDELY SCATTERED AFTERNOON THUNDERSTORMS Afternoon highs will once again warm into the low and mid 90’s over the plains with 80’s in the Front Range foothills. Normal high for Denver today is 90 degrees. Skies will begin sunny to mostly sunny and become partly to mostly cloudy as storms develop this afternoon. There is a surge of higher surface moisture over NE Colorado and if this feature pushes into the District the threat of heavy rainfall may end up being higher than anticipated. Otherwise, today is expected to be much like the past few days with thunderstorms developing over the foothills early in the afternoon then thunderstorm chances increase over the plains between 1-3pm. Isolated to widely scattered thunderstorm coverage is expected with typical storms producing light to moderate rainfall and gusty winds. Stronger storms may develop, especially if the higher surface moisture to the E makes it all the way back to the base of the foothills and strong storms will be capable of producing brief heavy rainfall that may lead to excessive runoff. Thunderstorms will generally move from W to E at 15-20mph but stronger storms that form along outflow boundaries may move more slowly/erratically. Thunderstorm chances will diminish by around sunset with generally dry conditions expected for the overnight period. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce rainfall rates of 0.1-0.4” in 10-30 minutes. Strong thunderstorms will have the potential to produce 0.4-1.2” of rain in 10-30 minutes. WORST CASE SCENARIO: Surface moisture increases from a boundary approaching from the E allowing for strong thunderstorms to produce rainfall rates of 0.5-1.5” in 10-30 minutes and up to 2.0” of rain in 45-60 minutes. A LOOK AHEAD: Isolated to widely scattered afternoon thunderstorms are expected again on Sunday and Monday with temperatures continuing to run in the low to mid 90’s for afternoon highs over the plains. Monsoon moisture is expected to increase on Tuesday and Wednesday with scattered to widespread afternoon thunderstorms and a higher risk of heavy rainfall. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Arapahoe 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Boulder 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Broomfield 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Denver 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Douglas 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Jefferson 200 PM TO 800 PM 0.1" (60%) to 0.4" (30%) to 1" (15%) MOD Foothills above 6500ft       Boulder 100 PM TO 800 PM 0.1" (80%) to 0.4" (40%) to 1" (15%) MOD Douglas 100 PM TO 800 PM 0.1" (80%) to 0.4" (40%) to 1" (15%) MOD Jefferson 100 PM TO 800 PM 0.1" (80%) to 0.4" (40%) to 1" (15%) 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]