A mostly sunny warm Monday at the end of a heat wave will turn turbulent as storms roll across metro Denver in the late afternoon, bringing heavy rain, lightning, hail, and possible flooding, according to the National Weather Service.
The storms will hit mostly after 5 p.m., weather service forecasters said. The weather service issued a flash flood watch, warning that meteorologists expect up to 2 inches of rain in less than an hour. This could lead to flooding, especially in low-lying areas within Colorado’s Front Range cities and in the mountain foothills where fires have reduced vegetation across burn scars. Weather service officials advised drivers to avoid flooded roads, watch for warnings and be ready to move to higher ground if flooding is imminent.
State health officials issued an air quality alert due to increasing pollution.
The high temperature in Denver will be 90 degrees — the tenth day in a row with highs above 90 — decreasing to 63 degrees at night, forecasters said. On Tuesday, the high is expected to be 86 degrees.
Meteorologists estimated the likelihood of rain Monday at 40%.
⚠️Flash Flood Threat Today⚠️
Afternoon and evening thunderstorms will be capable of producing very heavy rain. Burn areas, urban locations, small creeks and streams, and low lying areas will be most vulnerable.
— NWS Boulder (@NWSBoulder) July 31, 2023
The Colorado Department of Public Health and the Environment air quality alert warns that ground-level ozone air pollution has reached levels considered unhealthy for the elderly, children, and people with respiratory problems.
The worst pollution is expected in the southern and western parts of metro Denver, including Highlands Ranch and Golden. The alert, effective at least through 4 p.m., covers Denver and surrounding Douglas, Jefferson, western Arapahoe, western Adams, Broomfield, Boulder, Larimer, and Weld counties. State officials asked that metro Denver residents reduce driving in non-electric vehicles and refrain from using gas and diesel machinery.
Elevated ozone anticipated both Sunday and Monday during the afternoons and early evenings. Strenuous outdoor activities better suited for the morning, if possible. #SimpleSteps pic.twitter.com/6PGC0uQilp
— CDPHE Air Pollution (@cdpheapcd) July 30, 2023