Time: 842 AM Sun July 4, 2021 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- WIDELY SCATTERED AFTERNOON THUNDERSTORMS WITH THE POTENTIAL TO PRODUCE BRIEF HEAVY RAINFALL - Conditions over the District today will likely be somewhat similar to yesterday with widely scattered afternoon thunderstorms although with slower storm motions the threat for heavy rainfall is slightly higher. Temperature wise highs will again top out in the 90's over the plains with 80's in the Front Range foothills. - Dry conditions this morning will give way to initial thunderstorm development W of the District over the foothills between noon-1pm. Chances for thunderstorm activity increase over the plains between 1-3pm. Prime time for thunderstorms is from 3-8pm. Upper level steering winds from NW to SE at around 15mph will keep the the storms slowly moving along but stronger thunderstorms will have the potential to produce brief heavy rainfall and may become severe with gusty winds and hail being the primary threats. - After 8pm thunderstorm activity is expected to have diminished in time for the fireworks with generally dry conditions expected through the evening and overnight period. Have a happy and safe Independence Day from the MHFD! STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3" of rain. moderate to briefly strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A large, slower moving strong thunderstorm may result in up to 1.6" of heavy rainfall in 45-60 minutes. A LOOK AHEAD: Monday will feature an increase in moisture and the presence of a passing upper level disturbance. The result will be more thunderstorm activity with a much higher risk for heavy rainfall from thunderstorms that may lead to excessive runoff and possibly flash flooding. Best chances for thunderstorms will be from 2-10pm, lingering rain showers may continue overnight. Temperatures will drop 1-3 degrees Monday, mainly due to more cloud cover earlier in the day. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 800 PM 0.1" (75%) to 0.3" (50%) to 0.8" (15%) MOD Arapahoe 300 PM TO 800 PM 0.1" (75%) to 0.3" (50%) to 0.8" (15%) MOD Broomfield 300 PM TO 800 PM 0.1" (75%) to 0.3" (50%) to 0.8" (15%) MOD Denver 300 PM TO 800 PM 0.1" (75%) to 0.3" (50%) to 0.8" (15%) MOD Boulder 200 PM TO 800 PM 0.1" (80%) to 0.3" (50%) to 0.8" (15%) MOD Douglas 200 PM TO 800 PM 0.1" (80%) to 0.3" (50%) to 0.8" (15%) MOD Jefferson 200 PM TO 800 PM 0.1" (80%) to 0.3" (50%) to 0.8" (15%) MOD Foothills above 6500ft       Boulder 100 PM TO 800 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) MOD Douglas 100 PM TO 800 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) MOD Jefferson 100 PM TO 800 PM 0.1" (90%) to 0.3" (60%) to 0.8" (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]