Monsoon thunderstorms are still wreaking havoc across parts of the Southwest—and it’s almost fall.
Monsoon thunderstorms are still wreaking havoc across parts of the Southwest—and it’s almost fall.
So, when do these flooding desert storms finally end?
The North American monsoon typically peaks in July and August, then begins winding down in September as the seasonal wind pattern shifts.
But this year, a persistent upper-level ridge i.e., a heat dome over the US, is helping maintain southerly flow into the Southwest—acting like a conveyor belt, drawing deep tropical and monsoon moisture northward a little later this year.
Lingering summer heat is helping fuel lingering monsoon rains.
Warm ocean water is another piece of the puzzle.
After absorbing sunlight all summer, the Gulf of California and parts of the eastern Pacific are still very warm into early fall.
That warmer water helps load the air with moisture, eventually making its way to the desert Southwest, where it can load these storms with more fuel for heavy rain.
The classic monsoon pattern usually fades in October, though occasional tropical moisture surges can still produce big rainmakers.
