Newton (2016)

A tropical wave that moved into the eastern North Pacific developed into a tropical depression on September 4, 2016 about 210 nautical miles south of Manzanillo, Mexico. It became Tropical Storm Newton the same day and moved north-northwestward toward the southern tip of the Baja California peninsula. Newton intensified rapidly over very warm waters and minimal shear between September 4–6, becoming a hurricane by 1800 UTC on September 5 and reaching peak intensity on 0600 UTC September 6. The storm tracked across the southern Baja California peninsula, crossed the Gulf of California as a weakening cyclone, made a second landfall on the mainland of Mexico, then degenerated to a remnant low and moved into southern Arizona before dissipating.

Newton made two official landfalls. The first occurred near El Cuñaño on the west side of the Baja California Sur peninsula around 1400 UTC September 6 with maximum sustained winds of 75 knots (about 86 mph). The second landfall was just south of Bahía de Kino, Sonora, around 0830 UTC September 7 with winds of 55 knots (about 63 mph).

The hurricane’s maximum intensity was estimated at 80 knots (about 92 mph) with a minimum central pressure of 977 mb at 0600 UTC September 6, making it a Category 1 hurricane at peak. Aircraft data, satellite estimates, and surface observations supported the peak wind and pressure values.

Storm surge and heavy rains produced notable local impacts. Rainfall totals included 13.90 inches (353 mm) near Acapulco, 12.62 inches (320.5 mm) at Cihuatlán (Jalisco), and up to 12.20 inches (309.9 mm) at Mapastepec (Chiapas) from the precursor and Newton combined. In Baja California Sur, parts of Mulegé received up to about 5 inches (125 mm). In the United States, southeastern Arizona saw over an inch across a swath and localized amounts exceeding 6 inches (highest 6.57 inches in the Rincon Mountains east of Tucson). Reported wave heights near Bahía de Kino reached about 4 m (13 ft), and unofficially gusts near San Carlos reached about 70 kt at a marina; Bahía de Kino reported sustained 39 kt with gusts to 56 kt.

Newton caused both loss of life and substantial damage. Five direct deaths occurred when a shrimp boat capsized in rough seas in the Gulf of California while Newton was a tropical cyclone. Before Newton’s classification, heavy rains and flooding from its precursor caused at least three deaths in Chiapas and one death in Guerrero. Damage estimates included about 700 million pesos (~$37 million USD) in Baja California Sur—with heavy rain and landslides in Mulegé and Santa Rosalía—and about 1.1 billion pesos (~$58 million USD) in Guaymas, Sonora, where thousands of homes and many businesses were damaged and widespread power outages occurred.

Noteworthy aspects included Newton’s 36-hour period of rapid intensification prior to reaching the southern tip of Baja California Sur and a slightly slow official forecast track that delayed the predicted arrival of the center over the peninsula. NHC forecasts successfully anticipated genesis several days in advance, but track forecasts tended to be too slow bringing the center northward; some numerical models (GFS, HWRF) performed better than the official track forecasts for this storm.