Flash Flood Prediction Program

Time: 947 AM Mon July 11, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- TEMPERATURES TOO COOL FOR THUNDERSTORMS TODAY WITHIN THE DISTRICT - A cold front moved through this morning increasing clouds and turning winds to the N and even producing a little mist S of I-70 over the plains currently with the upslope flow. A much cooler air mass is in place today and will provide a break from the heat. - Highs this afternoon will only warm into the low to mid 80's over the plains with 70's in the Front Range foothills. Breezy N winds behind the front are already in the process of weakening and clouds will slowly decrease into the afternoon becoming partly cloudy. Temperatures would need to reach around 90 to initiate convection over the plains and with the cool temperatures forecast the air mass is expected to remain stable over the plains with generally dry conditions over the District. - Thunderstorm activity will develop to the S and SW of the District over the higher foothills where there is more sunshine currently and the atmosphere will be more unstable. As these storms are pushed to the E by upper level winds towards the District they are expected to dissipate on approach. A storm or two may survive long enough to produce an isolated rain shower or weak thunderstorm favoring areas S of I-70 and W of I-25. STORM RAINFALL POTENTIAL AND DURATION: Light rain showers or mist this morning will generally produce just a trace (TR) of precipitation. Rain showers and possibly a weakening thunderstorm will produce a trace to 0.2" of rain in 10-30 minutes. WORST CASE SCENARIO: Temperatures warm further than expected with thunderstorms becoming more likely over the plains with the potential to produce brief heavy rainfall. A LOOK AHEAD: Temperatures will climb into the upper 80's to lower 90's on Tuesday and with more heating thunderstorms will become likely. Widely scattered afternoon thunderstorms are expected to initiate by 1/2pm and continue possible through 8/9pm. Stronger storms will have the potential to produce brief heavy rainfall. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 800 PM MON Trace (15%) to 0.1" (10%) to 0.2" (5%) NONE Arapahoe Current TO 800 PM MON Trace (40%) to 0.1" (20%) to 0.2" (10%) NONE Boulder Current TO 800 PM MON Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Broomfield Current TO 800 PM MON Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Denver Current TO 800 PM MON Trace (20%) to 0.1" (10%) to 0.2" (5%) NONE Douglas Current TO 800 PM MON Trace (50%) to 0.1" (25%) to 0.2" (10%) NONE Jefferson Current TO 800 PM MON Trace (40%) to 0.1" (20%) to 0.2" (10%) NONE Foothills above 6500ft       Boulder 200 PM TO 800 PM Trace (60%) to 0.1" (30%) to 0.2" (15%) NONE Douglas 200 PM TO 800 PM Trace (75%) to 0.1" (50%) to 0.2" (25%) NONE Jefferson 200 PM TO 800 PM Trace (75%) to 0.1" (50%) to 0.2" (25%) 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]