5 important things to know about this year's monsoon season

·6 min read

Too much of a good thing has proven deadly in the Southwest.

With many areas in the region craving rainfall to bring long-needed drought relief, flash floods have answered that yearning at a steep, and in some cases, fatal price.

The annual North American monsoon, which officially runs from June 15 to Sept. 30, is a notable weather phenomenon for the southwestern United States in any year. But this year, in particular, has thrust the monsoon into the news for a number of different unique reasons.

Here are five of the most important things to know about this year's Southwest monsoon.

Flash flooding and seemingly nonstop storminess are common traits of the annual weather pattern, but not since 2015 has a monsoon season been as active as it has been thus far in 2021.

Areas such as Cedar City, Utah, have picked up more rainfall this past July than they had in the previous three Julys combined.

In Arizona, that heavy rain has fallen most extensively on Tucson, where more than half of a foot of rain has destroyed roads, washed away multiple people and rewritten the record books. Tucson International Airport had recorded 5.88 inches of rain since the start of the rainy season as of July 25, making it the wettest monsoon season to that date, according to the National Weather Service (NWS).

This past month, Tucson, which gets an average of 2.21 inches of rain per July, had recorded 8.06 inches of rain, making it the wettest July on record and the wettest month in recorded city history. August of 1955 comes in second with a total of 7.93 inches of rain, according to the NWS.

Equally stunning rain totals have also fallen over areas such as Phoenix and El Paso, Texas. Las Vegas, which received only a trace of rain during the entire 2020 monsoon season, has recorded 0.51 of an inch already this year.

The incredibly heavy rain has caused far more than travel nuisances. The flash floods they have triggered have proven calamitous.

At least five lives have been claimed by the widespread flooding, while multiple other people remain missing, and many others have required life-saving rescues across the region.

In Arizona, a 4-year-old girl, Maci Reed, perished from the storms after floodwaters in the town of Pima swept the girl away on July 22. Her body was found on July 26. According to the Graham County Sheriff's Office, Reed washed away from her family after their vehicle overturned on Cottonwood Wash Road.

This drone image provided by the Golder Ranch Fire District shows firefighters safely rescued a man and his two daughters from the roof of their vehicle after it was swept away in fast-moving water just north of Tucson, Ariz., on Wednesday, July 14, 2021. (Golder Ranch Fire District via AP)

Days later, another Arizona girl, 16-year-old Faith Moore, was swept away by a flash flood in Cottonwood. Moore had reportedly been trying to cross a flooded road in her car on Saturday evening.

In New Mexico, three individuals were washed away in Albuquerque while working in an arroyo, a dry stream bed that can turn into a flood channel amid heavy rain. According to Albuquerque Police, the three men perished, marking the deadliest flooding event in recent Albuquerque history, according to KRQE.

On July 27, another tragedy struck an arroyo in Albuquerque, washing away two men. One individual was rescued, but the other was not immediately saved and the operation shifted to recovery, the Albuquerque Fire Department said.

Earlier this month, monsoon rains in Grand Canyon National Park were also blamed for the death of 29-year-old Rebecca Copeland. Copeland was visiting the Tatahatso Camp on the Colorado River when floodwaters wreaked havoc.

In late July, a harrowing rescue of two men and a child was performed by bystanders after a vehicle was swept away by floodwaters in Tonto Basin, located to the northeast of Phoenix. The Good Samaritans captured every heart-racing moment on camera.

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According to some experts, the extreme drought is largely to blame for these tragedies, as moisture isn't being absorbed into the soil.

AccuWeather Chief On-Air Meteorologist Bernie Rayno broke down why seemingly small amounts of rain can lead to deadly flash flooding. The first factor has to do with the fact that a high-pressure system sets up over the Four Corners region during the monsoon. That not only funnels in moisture from the Gulf of Mexico that can provide fuel for downpours, but it also produces little wind across the region. The result can be slow-moving torrential thunderstorms.

The hard, dry soil of the region further exacerbates the flood threat, in addition to the terrain changes. Rainfall in higher terrain drains into lower-lying areas in the Southwest. Rayno used a paper towel and a hard surface to demonstrate how rainfall absorbs into different soils. When he poured the water over the paper towel, it absorbed the water. Meanwhile, when the water was spilled on a table, it spread over the hard surface, demonstrating what can happen when rain falls in the American Southwest.

The dim silver lining of the flooding rainfall has been the dent it has put into the region's severe drought. The relief from the rain is most helpfully benefitting portions of Arizona and New Mexico.

Even though most of Arizona is still facing some level of drought, there was a 32% drop in the area experiencing the two highest levels of drought, extreme and exceptional, over the last week as of July 27, 2021. (U.S. Drought Monitor)

Nearly 99% of Arizona was dealing with at least a moderate drought last week, although recent monsoon rainfall has started to put a dent in the areas facing the highest levels of drought: extreme and exceptional levels. This week, 52% of the state was dealing with at least extreme drought levels, a drop from 84% the week before, according to the U.S. Drought Monitor. Of that 52%, nearly 9% of the state was dealing with exceptional drought, a drop from 36% the week before last.

Part of what has made the 2021 monsoon season so notable was how uneventful the 2020 season was.

As AccuWeather forecasters foresaw months ago, the incredibly drenching 2021 season was keyed by the positioning of the high-pressure area. The opposite was true in 2020 when the position of the high suppressed rainfall.

AccuWeather Senior Meteorologist Alex Sosnowski said that if the high sets up too far west like it did in 2020, the flow of moisture from the Gulf of Mexico is cut off.

This year, however, a shift in that area's positioning has opened the floodgates, for both better and worse.

"This year, it has been centered farther to the east over the Rockies and Plains," Sosnowski said. "The clockwise circulation around the high is what pulls the moisture up from the Gulf of Mexico and Gulf of California into the Southwest." That moisture is what provides fuel to the torrential downpours that develop during the monsoon season.

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