Forecast now favors dry monsoons in eastern Arizona | news

But the news is not getting any better.

The National Weather Service says the odds have now turned in favor of drier monsoons than normal in eastern Arizona. As for the rest of the state – who knows?

“In western and central Arizona there are equal chances of above, near or below average rainfall. During the monsoon season, above normal temperatures are favored, ”says the latest NWS monsoon forecast.

In fact, the state is heading for a heat wave this week, with temperatures near 114 in Phoenix, over 100 in Rim Country, and the upper 90s in the White Mountains.

This is bad news for firefighters who are already fighting two or three major fires that have consumed more than 160,000 hectares.

Officially, the monsoon begins on June 15th. But it won’t actually rain until a rise in humidity from the ingress of moist air from the Gulf of California creates large thunderclouds in the afternoon. Even then, we typically have to battle gusty storms for a week or two, which produce more lightning than rain – increasing the risk of fire.

Still, we’re unlikely to have another summer like last year – the hottest Arizona summer in recorded memory. Not only did summer temperatures set records, but most of the state received less than 30% of normal monsoon rainfall. Flagstaff has set an all-time record at just 1.78 inches – compared to the 8 inches it normally gets. Payson usually gets about 3 inches and Show Low usually about 2 inches in July.

Areas now threatened with drier than normal monsoons include Bisbee, Chinle, Douglas, Globe, Show Low, St. Johns, Tucson, and Winslow.

Areas with a 50/50 chance of normal monsoon rain include Flagstaff, Grand Canyon, Kingman, Lake Havasu, Phoenix, Prescott, Sedona, and Yuma.

In the meantime, no matter how much rain we get, there will likely be temperatures a few degrees above normal across the state.

So it’s like Daryl Seymore, chairman of the board of directors of Navajo County, said last week, “Let’s all just pray for rain.”

But don’t blame the National Weather Service for being vague.

It turns out that the monsoons are notoriously difficult to predict – especially when a decade-long warming trend associated with the accumulation of heat-storing pollutants in the atmosphere is upsetting climate modelers.

Some models predict that the Arizona monsoons will weaken and possibly disappear in the coming decades.

Other models predict that the winter and spring rains could wear off and the monsoons might get stronger – it will become less reliable and more violent.

In addition, some recent archaeological studies have documented past droughts – monsoon cycles that have entrenched streams, wiped out irrigation systems, and displaced entire civilizations.

And as if that’s not enough, some recent studies still suggest we are still guessing when to predict the course of long-term droughts – like the record breaking 20-year “extraordinary drought” that is now sweeping most of Arizona.

That’s because the El Niño and La Niña cycles of surface water warming and cooling in the Pacific are actually much less of the normal rainfall fluctuations in the southwest than we thought, according to a study by researchers from Northern Arizona University published in Science Advances , the University of Columbia, the University of Washington, and the University of Southern California.

Many forecasters associate the warming of El Niño in the Pacific with wetter winters and wetter winters than normal Arizona monsoons. In contrast, they associate cooler La Niña events with dry winters in Arizona. That pattern played out this year with a bone-dry winter associated with the cooling of the ocean surface by La Niña in the eastern Pacific. Conditions in La Niña have largely disappeared and have contributed to the 50/50 forecast for the monsoons.

However, the new study found that El Niño cycles were only about 13% of the likelihood of a drought breaking out in the southwest, according to a research summary on the Science Daily website.

The researchers used tree ring records and drill cores from the sea floor to compare droughts and sea surface temperatures dating back 1,000 years. They relied on a growing database called Last Millennium Reanalysis, which combines temperature measurements, coral reef growth patterns, ice cores, and other data.

They found mega-droughts scattered over the past 1,000 years, including one linked to the collapse of civilizations in the Southwest in the 13th century – including those who lived in the Rim Country and the White Mountains.

They concluded that changes in the atmosphere had a greater impact on the likelihood of years of drought than sea surface temperatures. This is not necessarily good news for us, given the measured rise in global mean temperatures in the atmosphere.

“Our study suggests that in addition to the dehydration induced by global warming, the atmosphere will continue to add a highly unpredictable element to the humidity conditions in the southwestern United States,” said a study author Julian Emile-Geay, now at USC. “That said, the Southwest is headed for a drier future overall, but with the atmosphere that adds a wildcard that can sometimes make things better or worse for people and the water-dependent ecosystems.”

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