Tag: Southwest monsoon

Is global warming changing the Southwest monsoon?

Study shows more intense but less frequent storms

Monsoon precipitation is an important part of the water cycle in the dry western half of the U.S. so climate scientists are trying to figure out global warming will affect the pattern. @bberwyn photo.

An international research team says monsoon storms in the Southwest have become less frequent but more intense, bringing more extreme wind and rain to central and southwestern Arizona than just a few decades ago.

The study, led by scientists with the University of Arizona, compared precipitation records from 1950 to 1970 with data from the 1991-2010 period to verify their climate model, scaled down to capture changes at a resolution of 1.5 square miles. At that level of detail the changes over time became apparent, while models using a 10 square mile grid aren’t able to accurately recreate the precipitation trends. Continue reading “Is global warming changing the Southwest monsoon?”


Will Hurricane Norbert soak Colorado?

Big surge of subtropical moisture possible early next week

Moisture will be plentiful across Colorado and much of the U.S. the next 5 days.


FRISCO — Hurricane Norbert, now spinning off the coast of Baja, California, could deliver copious amounts of moisture to Colorado early next, according to the National Weather Service, which is already talking about the potential for regional flash flooding.

The Category 3 storm is expected to weaken gradually during the next few days as it moves northwest over cooler water, but the projected path turns the remnant low pressure system eastward, coming ashore over northern Mexico or southern California late in the weekend.

The exact path will determine how much rain falls in Colorado, but National Weather Service forecast maps are showing widespread rain across Colorado, with a bullseye over the north-central mountains.

Grand Junction-based National Weather Service forecasters say subtropical moisture will increase across the Great Basin and western Colorado Monday as a low pressure area off the SoCal coast directs Nortbert’s remnants and more monsoon moisture northeastward.

Storms will be widespread by Monday afternoon with the potential for heavy rain and small hail, as well as a chance for flash floods and debris flows.

Dry air (brown) prevailed over Colorado Saturday morning, but Hurricane Norbert may help boost another surge of late-season monsoon moisture poised to the south.

Climate: Wet West in July

Energetic monsoon brings moisture surplus to many areas

The big wet?

By Summit Voice

FRISCO — An energetic and widespread monsoon weather pattern brought above normal precipitation to much of the West in August, with a bullseye of moisture in southern Idaho, extending across western Wyoming, Montana, northeastern Utah and into northwestern Colorado. Some locations in the region saw up to 800 percent of average precipitation. Continue reading “Climate: Wet West in July”

Morning photo: Twilight set

More monsoon

Clearing late-summer storm over Dillon Reservoir.

FRISCO — Monsoon season just won’t quit in Colorado this year. That’s a boon for mushroom lovers, who continue to report good finds around the high country, and it’s also dampened the fire season across much of the state. But while the stream of moisture feels summer-like, there’s already been a subtle shift in the quality of the light. We’re closer to the equinox than the solstice now, and the sun slants in from a noticeably different angle at sunset. Continue reading “Morning photo: Twilight set”

Colorado: Monsoon arrives right on schedule

Daily rain showers to persist through the weekend

A classic monsoonal flow of moisture, moving clockwise around a
A classic monsoonal flow of moisture, moving clockwise around a high pressure center over the Texas panhandle, is delivering plentiful moisture to parts of the parched Southwest.

By Bob Berwyn

FRISCO — Flashes of lightning, loud thunder and heavy rains Friday marked the start of Colorado’s summer monsoon season. The one- to 2-month period when moist and warm air flows northward from the subtropics may not be as dramatic as the Asian monsoon, but it’s still a critical piece of the state’s overall weather picture, providing abundant moisture just at the time when forests and fields are reaching their driest point. Continue reading “Colorado: Monsoon arrives right on schedule”

Climate: Southwest tree rings show historic monsoon droughts

Ancient Douglas firs are helping researchers track historic patterns of drought. Bob Berwyn photo.

New technique focuses on late-summer tree ring growth to pinpoint seasonal climate patterns

By Summit Voice

SUMMIT COUNTY — A detailed new study of tree rings in the Southwest shows that  patterns of alternating wet and dry seasons observed since the 1950s is not the norm. Rather, the analysis suggests that, during historic decadal droughts, both winter and summer precipitation was below the long-term average.

The new 470-year-long history (1539 to 2008) of summer precipitation in the Southwest covers most of Arizona, western New Mexico and parts of northern Mexico. It was established by looking at rings from Douglas firs and ponderosa pines, including tree-ring samples stored in the archives of the University of Arizona Laboratory of Tree-Ring Research. Continue reading “Climate: Southwest tree rings show historic monsoon droughts”