The monsoon season starts this Thursday, but desert dwellers may have to wait a little longer for the rains to actually come.
the forecaster predicts Southern Arizona could experience a hotter, drier overall summer with delayed seasonal storm cycles.
“At this point, we don’t expect a full monsoon collapse. This looks a little different,” says Mike Crimmins, a climatologist at the University of Arizona. “But I’m gearing up for a slow start.”
The southwest monsoon season officially begins on June 15 and runs through September, but weather data from the past 80 years shows that Tucson often doesn’t see its first storm activity until early July.
Crimmins said the “strange low-pressure valleys” of recent weeks have kept temperatures in Tucson mostly in the double digits, but have also prevented the formation of anticyclonic ridges that cause monsoon storms. said there is.
This ridge usually forms in southern Mexico and gradually continues up to us. But so far there have been no signs of that, Crimmins said. “You can’t fly over Mexico. You really have to start there and develop further north.”
On August 6, 2022, a monsoon storm hit Vail and twin bolts hit the southern slopes of the Rincon Mountains.
Lower-than-average rainfall expected
latest seasonal forecast National Weather Service Climate Prediction Center Most areas of New Mexico and Arizona are showing below-normal rainfall through August. The long-term outlook could see above-average temperatures in Arizona and New Mexico over the next three months.
Both of these precipitation and temperature forecasts suggest a late development of the monsoon pattern, but they tend to be less accurate the further away they are.
“This can all be a disaster,” says Crimmins, a professor and extension expert in the UA School of Environmental Sciences.
First, he said, climate researchers still don’t fully agree on what factors influence monsoon activity and to what extent. “It’s a frustrating time[as a forecaster]because we have all these statistical models and supercomputers and we’re still squinting at the output.”
A monsoon storm over the Santa Catalina Mountains as seen from “A” Mountain in Tucson.
Flood Tracking Network Expands
The Pima County Regional Flood Management District is preparing for the monsoon season by expanding the reach of its flood tracking network, known as ALERT. Automatic local assessment in real time.
Since last year, five river flow gauges and six rain gauges have been added to the system, which now tracks 125 precipitation and 54 flood streams countywide.
The Regional Flood Service will also monitor increased flooding in 2020 from bighorn fires that set fires across the range and scorched vegetation that once absorbed water and reduced erosion. We have installed two new live cameras along the way.
This brings the total number of live cameras to five, all in the Catalina Islands, paid for through the state’s forest grant program to support wildfire restoration.
And plans for future additions to the ALERT system are already underway, including the first of several rain gauges and river flow meters on tribal lands administered by the Pasqua Yaki and Tohono O’odham tribes. things are also included.
“The district has a history of working proactively and cooperatively with other jurisdictions, and we look forward to building ties with the Indigenous communities that are an integral part of Pima County,” said Deputy Director. said Brian Jones. District floodplain manager.
A rainbow appears over the historic Pima County Courthouse after a storm in downtown Tucson, Arizona, on September 13, 2022.
El Niño in progress
Climate forecasters are also tracking an outbreak of a potentially strong El Niño, a tropical oceanic climate phenomenon that typically brings winter rains to the southwest.
“It’s definitely present in the Pacific and seems to represent some strength,” Crimmins said. “We’ve seen it seep in since last winter, and now it’s really starting to come together.”
He said El Niño’s impact on the Southwest monsoon pattern is not “very stable,” but it could extend the tropical storm season in the Gulf of California and bring heavy rainfall to southern Arizona in the fall. said there is.
El Niño effects are more predictable during the winter months, and the phenomenon often, but not always, causes regional wet conditions.
Crimmins said a return of wet winters in parts of the West following last year’s near-historical snowfall could reduce water supplies and prolonged droughts, especially in Arizona and six other states that depend on the Colorado River. said it would have a tremendous impact on
Just after sunset on August 23, a lightning strike occurred behind Tumamoku Hill. The storm caused localized flooding due to heavy rain.
big changes in recent years
In 2021, Tucson will experience the third wettest monsoon on record, with the city’s official weather station at Tucson International Airport receiving a whopping 12.79 inches of rain. More than 8 inches of rain fell that July alone, making it the heaviest month observed by Tucson in at least 126 years.
Last year we had a below average monsoon, with just under 5 inches of precipitation for the season.
But even that came in 2020, when Tucson was hit by the second driest monsoon on record (only 1.62 inches of precipitation) and total annual precipitation was about to reach a historically low level of just 4.17 inches. It felt like a big deal in comparison.
The Crimmins don’t expect the same to happen this year. The 2023 monsoon may come later, but “it will definitely happen,” he said.
Immediately after reflecting on his use of the word “promise,” the climate scientist offered an important explanation.
“Monsoon ridges will definitely exist,” he explained with a laugh. “I can’t promise that it will rain at your house.”
