The Summer Monsoon

20160628_181924_resized

Looking northwest toward the Jemez Mountains during monsoon season

Many visitors to Santa Fe are surprised to hear that our rainy season is July and August. And when they hear locals using the word “monsoon” they occasionally express alarm! But we New Mexicans love our summer monsoon, and indeed well over half our annual rainfall falls during these two months. By August much of the low juniper-grassland country is flushed green. The conifer-aspen forests in the high country drip with moisture and  mushroom-hunters begin appearing in the woods.

Monsoon stems from an Arabic word for season, or shift in the wind. In the American Southwest, a combination of factors sets up humid southerly winds starting in late June or early July, giving us the one critical element of thunderstorm formation we usually lack: moisture. The other two, lift and instability, are always waiting in the wings here in New Mexico, with powerful daytime heating and mountain ranges in place. Here’s a graphic that shows the atmospheric factors:

monsoonAnd so, on many summer days, the late morning sky over the mountains will suddenly take on this appearance:

20160628_124150_resized

Cumulus forming over the Valle Grande west of Santa Fe

and you know somebody is going to get drenched. This is a constant consideration for hikers, who need to be prepared for sudden showers and the dangers of lightning at this time of year.

Sometimes these storms will persist into the summer night (giving Santa Fe Opera lovers some extra special effects), but just as often the clouds break up into a glorious sunset and leave behind a cool and refreshing evening.

By mid-September this seasonal southerly flow of wind dies down, to be replaced by the calmer, drier, and cooler air of early autumn. Santa Fe and the Southern Rockies are drenched in golden light rather than pouring rain, and the season many visitors regard as the best of all is upon us.

Posted in Current news&events, Nature&history | Leave a comment