Jun 21, 2022 - News

Arizona could see above average rainfall this summer

Lightning strikes over Mesa Arizona during a monsoon on August 17 2020

Lightning strikes as a monsoon storm blows over Mesa on Aug. 17, 2020. Photo: Michael Chow/The Arizona Republic via Imagn Content Services, LLC

Odds are good that Arizona will see a wetter-than-normal monsoon season, especially in July, according to the National Weather Service (NWS) Phoenix.

  • That should come as welcome news for a state grappling with major wildfires and a 22-year drought.

The big picture: Nothing is certain, but conditions favor above-average rainfall in July, with normal monsoon conditions likely returning in August and September, NWS Phoenix meteorologist Marvin Percha told Axios.

  • Average monsoon season rainfall measured at Phoenix Sky Harbor International Airport was 2.43 inches from 1991-2021, Percha said.

What he's saying: Percha described the likelihood of a wet monsoon season as a matter of probability, telling Axios, "It's kind of like the deck is stacked in our favor. Maybe if you think of it like a deck of cards with a few extra aces thrown in there, it makes it easier for you to draw a blackjack."

  • The amount of rainfall around the state varies from the Sky Harbor measurement, with southeastern Arizona, the Mogollon Rim, and the eastern and northern edges of the Phoenix area seeing more, and the southern and western parts of the state seeing less.

Context: Arizona saw above-average monsoon rainfall last year, with 4.2 inches measured at Sky Harbor, which followed a drier-than-normal summer in 2020, when only 1 inch of rain was recorded.

Why it matters: More rain means a reduced wildfire threat at a time when Arizona is experiencing a heightened risk of the events.

A vigorous monsoon season will also benefit farmers and ranchers in Arizona, some of whom have seen their allocations of Colorado River water from the Central Arizona Project cut.

Yes, but: It's unlikely to do much to alleviate the massive "megadrought" that's battering the western U.S., Percha said.

  • However, heavy rainfall from last year's monsoons increased the water level at various reservoirs, when they would normally fall.

Zoom out: The current drought is the worst the region has experienced in about 1,200 years.

  • "It's more important for the shorter term, the smaller scale, such as the fire weather danger and the [agriculture] community," Percha said.

It still helps: NWS' latest seasonal drought outlook, which was issued Thursday, now lists drought conditions in most of the state as persisting but improving, with part of central Arizona listed as, "Drought removal likely."

  • That's an improvement from the May 31 seasonal outlook, which showed all of northern and western Arizona in the worst category of "Drought persists."

The bottom line: Percha said long-term improvement in Arizona's drought conditions would require increased winter rainfall, which is what reservoirs rely on for replenishment.

  • The ongoing La Niña event in the tropical Pacific Ocean is also likely to worsen drought conditions in Arizona and other southwestern states, Axios climate and energy reporter Andrew Freedman reported last week.

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