By Katie Marsal

Published: 10:48 AM EST (07:48 AM PST)

New 13- and 15-inch MacBook Pros with a thinner and lighter design are expected to launch in April "at the soonest," with an initial shipment of just under a million units.

Sources in Apple's upstream supply chain indicated to DigiTimes that Apple will launch upgraded MacBook Pros as early as April, with about 900,000 units expected to be shipped at launch. A redesigned version of the 17-inch MacBook Pro is apparently not expected at launch, as it was not mentioned in Wednesday's report.

That's consistent with what AppleInsider detailed earlier this month, revealing that Apple will launch a larger 17-inch model later than the 15-inch model the company is said to be prioritizing. Apple employed the same approach when it redesigned its MacBook Pro lineup in 2008, as the lower-volume 17-inch model became available a few months later.

Apple's upgraded MacBook Pro lineup along with new MacBook Airs and the forthcoming OS X 10.8 Mountain Lion Mac operating system upgrade are expected in the industry to pose a "significant threat" to notebooks designed to Intel's thin-and-light Ultrabook specification.

"Since Intel is delaying the mass supply of its Ivy Bridge CPUs from April to June, notebook vendors are concerned about... the postponed launch schedules of their ultrabooks, as it may give Apple advantages in terms of time-to-market," the report said.

Earlier this week, an Intel executive indicated that the company's next-generation Ivy Bridge chips are expected to debut eight to 10 weeks later than previously planned. That would push the launch of those chips from April until June.



But it's possible that Apple could still launch new notebooks powered by Ivy Bridge as early as April, if Intel were to give the Mac maker early access to its first run of processors. In the past, Apple has been given early availability of Intel's latest technology before other PC makers.

As Apple gears up to revamp its MacBook Pro lineup and borrow design cues from its successful MacBook Air, PC makers are still hoping to capitalize on the Ultrabook specification being pushed by Intel. Ultrabooks are intended to be less than 21 millimeters thick, weigh no more than 3.1 pounds, use flash-based solid-state drives, and offer 5 to 8 hours of battery life.

But initial Ultrabooks from Windows-based PC makers struggled to compete with Apple on price, as the entry-level 11.6-inch MacBook Air carries a $999 cost. And they also felt the squeeze from Apple on components, as PC makers struggled to obtain unibody metal notebook chassis for their products.