STOCKBRIDGE — Local police are gearing up for some of the most chaotic congestion of the year in town as the Congregation of Marian Fathers commemorates the annual Divine Mercy Weekend. As many as 16,000 celebrants are expected. “Traffic will be heavy, stay out of town,” Police Chief Darrell Fennelly advised. “Don’t add to the chaos.” The smaller event is on Saturday, with 4,000 to 6,000 worshippers expected, he said. All parking on that day will be on the 350-acre Marians’ Eden Hill site. But on Sunday, with at least 10,000 additional people likely to attend, there are satellite parking lots for automobiles at the Lee Premium Outlets off Route 102 and at Monument Mountain Regional High School in Great Barrington. Shuttle buses will be provided by the Marians. All 88 buses transporting groups of celebrants will be accommodated on Eden Hill, Fennelly said. He cited possible thunderstorms on Saturday, “not what we’re look[ing] forward to, but we’ve dealt with it in the past, so we should be OK.” The event held annually since 1941 (except in 2020 during the pandemic) is at the National Shrine of The Divine Mercy, the home of the Marian Fathers of the Immaculate Conception. Throughout the weekend, the shrine grounds are transformed into a small tent city, according to an announcement from the Marians. Weekend highlights at the outdoor shrine on Eden Hill include the 4 p.m. Saturday Vigil Mass and the 1 p.m. Sunday Mass celebrated by the Rev. Donald Calloway. His 20 books include “Consecration to St. Joseph: The Wonders of Our Spiritual Father,” “Passion Gems: Daily Wisdom on the Suffering, Cross, and Death of Jesus” and, soon to be published, “The Virtues of the Saints: 15 Healthy Habits for Children.” The Sunday Mass will be livestreamed on Facebook and on the Marian Fathers' dedicated streaming site, DivineMercyPlus.org. Among about 300 volunteers will be translators providing assistance to visitors in Spanish, Polish, Italian, French, German and Tagalog, a language spoken in the Philippines. Meanwhile, construction has been continuing on a new monastery and community chapel for the Congregation of Marian Fathers. When completed, the 40-room, 20-office complex will provide congregate living for 40 priests, brothers and seminarians. Work began last December on the $29 million project, due for completion in fall 2026. An ongoing capital campaign has raised nearly $34 million from more than 13,000 donors. The Congregation of Marian Fathers is a fraternal community of the Roman Catholic Church. “Congregation members are devoted to Mary Immaculate, dedicated to praying for the poor souls in purgatory, and committed active service to the church," according to the Marians' website. Founded in Poland in 1670 by St. Stanislaus Papczynski, the Marian Congregation has more than 500 priests and brothers in the U.S. and 18 other countries. There are an estimated 2 million members of the congregation in 20 countries around the globe.