Flash Flood Prediction Program

Time: 905 AM Fri June 3, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- AN UPTICK IN THUNDERSTORM ACTIVITY EXPECTED TODAY/BRIEF HEAVY RAINFALL POSSIBLE - An upper level disturbance will move overhead early this afternoon and result in an uptick in thunderstorm activity today over the District. Temperatures will warm into the 70's to around 80 over the plains with 60's and 70's in the Front Range foothills. Surface dew points in the mid 40's to around 50 will support brief moderate to heavy rainfall from stronger storms that develop today which may lead to excessive runoff roadways. - The first storms will begin to develop over the foothills before noon with westerly upper level flow pushing the storm activity onto the plains by around noon or shortly after. Prime time for thunderstorm activity will be from noon to 5 or 6pm. After 5 or 6pm any shower and thunderstorm activity will be on the decrease with dry conditions developing for the later evening and overnight period. - Storm motions will be from W to E at 15-20mph. Modest storm motions will keep storms moving along and moderate to heavy rainfall brief in duration. Stronger storms today will favor areas E of I-25 over the plains but a strong storm cannot be ruled out towards the foothills. Strong thunderstorms may also contain hail, gusty winds and frequent cloud-to-ground lightning as well as brief moderate to heavy rainfall. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm anchors briefly along a surface wind convergence boundary resulting in heavy rainfall of up to 1.5" in 45-60 minutes. A LOOK AHEAD: Warmer and drier on Saturday with highs well into the 80's over the plains with 70's in the foothills. There will still be a chance for isolated afternoon thunderstorms but with less surface moisture to work with storms will favor the higher terrain with many plains locations on the dry side. Similar setup for Sunday with isolated afternoon thunderstorm activity favoring the foothills. The weather pattern will become more active late on Monday into Tuesday with cooler temperatures and better chances for showers and thunderstorms. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (15%) MOD Arapahoe 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (15%) MOD Boulder 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (10%) LOW Broomfield 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (10%) LOW Denver 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (15%) MOD Douglas 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (10%) LOW Jefferson 1200 PM TO 600 PM Trace (75%) to 0.3" (40%) to 0.8" (10%) LOW Foothills above 6500ft       Boulder 1100 AM TO 600 PM Trace (85%) to 0.3" (40%) to 0.8" (10%) LOW Douglas 1100 AM TO 600 PM Trace (85%) to 0.3" (40%) to 0.8" (10%) LOW Jefferson 1100 AM TO 600 PM Trace (85%) to 0.3" (40%) to 0.8" (10%) 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]