Flash Flood Prediction Program

Time: 832 AM Thu July 21, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- CONTINUED HOT WITH A DECREASE IN THUNDERSTORM ACTIVITY - The streak of 90-degree plus days will continue over the plains with a decrease in thunderstorm activity today. Highs this afternoon will be 1-3 degrees warmer than yesterday with highs in the mid 90's to around 100 degrees over the plains. - Moisture will decrease leading to a down-tick in thunderstorm activity today. Isolated afternoon thunderstorms remain possible but with less moisture to work with the storms that develop will be high-based producing mainly light rainfall and gusty winds. Many areas of the District likely end up on the drier side today. - Best chances for thunderstorms today will be over the foothills and Palmer Divide between 2-8pm. After 8pm dry conditions are expected for the remainder of the evening and overnight period. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak to briefly moderate thunderstorms will produce rainfall amounts of a trace to 0.2". WORST CASE SCENARIO: A stronger thunderstorm is able to develop with the potential to produce rainfall rates of 0.2-0.5" in 10-30 minutes. A LOOK AHEAD: We will tack on a few degrees to high temperatures on Friday with readings in the 90's to lower 100's over the plains. Much like today the thunderstorm activity will favor the higher terrain with minimal coverage over the plains and many areas likely dry. Better chances for thunderstorms on Saturday with temperatures backing off a few degrees due to increased cloud cover. On Sunday an upper level disturbance and cold front will lower temperatures into the 80's and increase moisture leading to stronger thunderstorms with the potential to produce heavy rainfall. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.2" (5%) NONE Arapahoe 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.2" (5%) NONE Boulder 200 PM TO 800 PM Trace (40%) to 0.1" (20%) to 0.2" (5%) NONE Broomfield 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.2" (5%) NONE Denver 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.2" (5%) NONE Douglas 200 PM TO 800 PM Trace (40%) to 0.1" (20%) to 0.2" (5%) NONE Jefferson 200 PM TO 800 PM Trace (40%) to 0.1" (20%) to 0.2" (5%) NONE Foothills above 6500ft       Boulder 100 PM TO 800 PM Trace (50%) to 0.1" (25%) to 0.2" (10%) NONE Douglas 100 PM TO 800 PM Trace (50%) to 0.1" (25%) to 0.2" (10%) NONE Jefferson 100 PM TO 800 PM Trace (50%) to 0.1" (25%) to 0.2" (10%) 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]