Miriam Becomes Major Hurricane Off Mexico But no coasts expected to be affected. By Newser Editors and Wire Services Posted Sep 24, 2012 10:21 AM CDT 0 comments Comments This NOAA satellite image taken Sunday, shows an area of clouds and showers over the northwest United States and into the Great Basin. ((AP Photo/Weather Underground)) (Newser) – US forecasters say Miriam has strengthened into a Category 3 hurricane off Mexico's Baja California peninsula. Miriam, which formed yesterday in the Eastern Pacific, is packing top sustained winds of 120mph, classifying it as a major hurricane, the National Hurricane Center in Miami said. The center says Miriam was moving northwest at 12mph. No coastal watches or warnings are in effect, but swells will hit Baja's southern and western shore during the next couple of days. In the open Atlantic, Tropical Storm Nadine was meandering far from land with top sustained winds of about 50mph.