Clouds build up in the early afternoon and gusty winds push in every direction. The skies darken and then comes the rain — often a downpour that is gone as quickly as it came. This seasonal dance marks a special time for the southwestern United States and Mexico. It is when residents clasp their hands, hoping for much-needed moisture to dampen the threat of wildfire and keep rivers flowing. Forecasters say it has been a wet start to this year’s monsoon season, which officially began June 15 and runs through the end of September. Parts of New Mexico and West Texas have been doused with rain, while Arizona and Nevada have been hit with dust storms, which are a common hazard of the season. In other parts of the world, monsoons often mean months of never-ending rain. In North America, the season can have considerable variability. The bursts and breaks depend on how much moisture is circulating and which way the wind blows. Easing drought The monsoon relies on the buildup of summer heat and shifting wind direction, which helps funnel moisture from distant bodies of water to areas where rain is sparse. Just ahead of the monsoon, officials with the Navajo Nation declared an emergency because of worsening drought conditions across the reservation, which spans parts of New Mexico, Arizona and Utah. Below-average precipitation month after month has left little forage for livestock, and fire danger has ramped up as pockets of moderate and severe drought expand. Ranchers and farmers are being urged to reduce their herds, shift to drought-tolerant crops and limit irrigation. New Mexico’s governor also declared an emergency in May because of severe drought and escalating fire risk. Forecasters with the National Oceanic and Atmospheric Administration and the National Integrated Drought Information System say monsoonal rainfall only provides a fraction of the West’s water supplies, with the majority coming from snowpack. Still, summer rains can reduce drought impacts by lessening the demand for water stored in reservoirs, recharging soil moisture and groundwater, and reducing the risk of wildfires. New Mexico and Arizona typically stand to benefit the most from the North American monsoon, getting anywhere between 10% to 60% of their annual precipitation during the season. It has a lesser influence in Nevada and California, though southern Nevada on average gets 20% to 25% of its precipitation during the summer. Along the Rio Grande at the base of the Jemez Mountains, Santa Ana Pueblo farmers are eagerly watching the afternoon skies. Pueblo Gov. Myron Armijo said they have already had several good downpours, and he wouldn’t mind more. Flooding fears With summer rains come increased river flows and in some cases flooding in normally dry washes and across the scars left by wildfires. Sandbag stations have been set up in communities across the region — from Tucson, Arizona, to Albuquerque and San Antonio, Texas. In Española, state transportation workers have closed a historic bridge that funnels traffic across the Rio Grande, citing concerns about higher flows further eroding a concrete pier. On the edge of the Gila National Forest, New Mexico National Guard troops have delivered dozens of pallets of filled sandbags for residents who are preparing for flooding following a blaze that has charred about 74 square miles (192 square kilometers). Meanwhile, hundreds of firefighters are […]