Poor air quality from wildfires continues to plague New York City as several neighborhoods hit by thunderstorms Saturday is delivering a double dose of dangerous weather across the…

Poor air quality from wildfires continues to plague New York City as several neighborhoods hit by thunderstorms Saturday is delivering a double dose of dangerous weather across the north-eastern US, with smoky skies from Canadian wildfires giving way to severe thunderstorms that have already triggered a flash flood warning as torrential rain pounds parts of the region. After a brief break on Friday, smoke from the wildfires moved back into New York City and surrounding communities on Saturday, sending air quality back into unhealthy levels. Conditions are expected to gradually improve as shifting winds push the smoke away, but those same changing conditions are fueling a new threat: strong to severe thunderstorms that are expected to sweep across much of the region, clearing the haze while bringing the potential for dangerous weather. The first wave of powerful storms moved through northern New Jersey and New York City on Saturday, prompting a flash flood warning through 2pm. Videos shared on social media showed water pouring into parts of the city’s vulnerable infrastructure, including Penn Station. By the afternoon, more than 2.5in (6cm) of rain had fallen in some locations, with flooding either under way or expected in areas covered by the warning. Neighborhoods including Jamaica, Crown Heights, Forest Hills, Ozone Park, Brooklyn Heights, Park Slope, Woodside and Greenpoint were among those affected. Forecasters warn the storms could produce torrential rainfall capable of causing flash flooding, damaging wind gusts and even isolated tornadoes before the day is over. Hail is also possible. The National Weather Service has placed much of the tri-state area under a level 3 (out of 5) risk. Unlike the more typical scattered severe storms, this level indicates numerous severe storms are likely. Meanwhile, Texas continues to battle the aftermath of days of destructive storms and historic rainfall. Although the prolonged rain has ended across Texas Hill Country, forecasters are now closely monitoring major rivers expected to surge south through the weekend.