(NEW YORK) — The monsoon season, a weather pattern affecting the western United States, is expected to continue for several weeks following a significant dust storm in the Phoenix area. The North American Monsoon is an annual climate event that occurs in the Southwest during the warm summer months.

During summer, intense heat from the sun causes temperatures to rise significantly in the Southwest. This heat creates a phenomenon where moist air is drawn toward the hot, dry air over land, leading to the development of the monsoon. The moist air moving onto the hot land destabilizes the atmosphere, resulting in thunderstorms.

The North American Monsoon is distinct from the Indian monsoon, which is characterized by prolonged heavy rainfall. In contrast, the North American version typically features dry mornings with storms developing later in the day, particularly in the afternoon and evening. This pattern is known as a diurnal cycle.

Moisture from the Gulf of California and the eastern Pacific Ocean contributes to the monsoon, affecting areas in California, southern Nevada, and Arizona. The season usually begins around May or June, intensifying in July and August, especially when tropical systems are present in the eastern Pacific.

While the unstable atmosphere can lead to thunderstorms, it is not a single storm but rather a pattern that encourages their formation. Monsoon thunderstorms can be slow-moving and persistent, resulting in heavy rainfall in arid regions, which may cause flash flooding. Some storms can be severe, producing heavy rain and frequent lightning.

Recently, much of the West has experienced monsoon conditions, resulting in some of the wettest days of the year. Summer thunderstorms in desert areas can generate strong winds, which may create dust storms. These dust storms can reduce visibility and pose travel hazards. They can appear suddenly, often as a wall of dust, with visibility dropping to one-fourth of a mile or less.

On Monday, a dust storm, known as a haboob, swept through the Phoenix metro area, causing low visibility and power outages for thousands. A massive cloud of dust was visible, and heavy rains and strong winds followed. Wind gusts reached up to 70 mph, grounding some flights at Phoenix Sky Harbor International Airport and prompting air traffic controllers to evacuate the tower.

The impact of the monsoon can vary from season to season due to the sporadic nature of thunderstorms. In Tucson, Arizona, the current monsoon season has produced just under 2 inches of rain, marking one of the drier seasons on record. In contrast, the 2021 monsoon brought 12.79 inches of precipitation to the area.

Rainfall during the monsoon is crucial for the region, as Arizona and New Mexico receive over 50% of their average annual precipitation from July to September. The monsoon season typically concludes in late September or early October when the land cools and wind patterns shift back to a westerly direction.