The NHC alert said: "At 9am MDT (2pm GMT) the eye of Hurricane Bud was located near latitude 16.7 North, longitude 106.8 West. Bud is moving toward the northwest near 7 miles per hour (11 km/h), and this motion is expected to continue today and tonight with a decrease in forward speed".
With maximum sustained winds of 115mph, Hurricane Bud is expected to rip through the western coasts of Mexico in the coming days.
The hurricane is moving north-west at about 10mph - a course it is expected to take until mid-week, the NHC said.
"Some additional strengthening is possible today, but a slow weakening trend is expected to begin on Tuesday", the NHC said. It is expected to bring rain to much of southwestern Mexico, with isolated amounts of 10 inches.
A tropical storm watch was issued by the government of Mexico for Manzanillo to Cabo Corrientes, The Weather Channel reported. "These rains could cause life-threatening flash floods and mudslides", the agency warned.
Hurricane Bud is the sequel to last week's Hurricane Aletta, which was eventually downgraded to a tropical storm.
Hurricane forecasters are watching another blob of showers and thunderstorms in what's turning out to be a messy start to the Atlantic hurricane season.
That's according to the National Hurricane Center, which pegged the disturbance's chance of organization in the next two days at just 10% in this afternoon's tropical weather outlook.
Meanwhile, Tropical Storm Aletta's winds were down to 40 miles per hour (65 kph) and it was predicted to dissipate by late Monday or early Tuesday.