By Slash Lane

Published: 03:50 PM EST (12:50 PM PST)

The latest U.S. sales data shows Apple's Mac sales are up 20 percent year over year, putting the company on pace to meet an expected 3.6 million units sold in the March quarter.

The new domestic sales data from the NPD Group was shared Tuesday by analyst Gene Munster with Piper Jaffray. Munster said he believes the early numbers, representing the first month of Apple's second quarter of fiscal 2011, show the Mac maker on track to meet Wall Street expectations.

Currently, investors expect to see about 22 percent year over year growth in the March quarter, resulting in 3.6 million units. Though U.S. sales were up less -- 20 percent -- in January, Munster noted that Apple has seen faster international growth of the Mac platform.

Mac sales are expected to receive a boost this week, when Apple is believed to release an update to its MacBook Pro line of notebooks. Munster said the new MacBook Pros will likely provide a tailwind for Mac sales in the final month of the March quarter.

The analyst said he believes Apple has also seen continued strong demand for its new thin-and-light MacBook Air. He noted that the entry-level $999 11-inch MacBook Air occupies the most prime store real estate in the company's retail outlets. In his eyes, this could signal that the MacBook Air Air has supported portable Mac sales while users await new MacBook Pro models, which have not been updated since last April.

Also included in the last NPD numbers are U.S. iPod sales, which were down 10 percent year over year in January. Projecting iPod sales based on NPD figures is more difficult, because international iPod sales represent a larger mix than international Mac sales.

Munster said the latest data shows Apple on track to sell between 9.8 million and 10.3 million iPods in the March quarter. That would mean iPod unit sales of between 5 percent and 10 percent less than the same frame in 2010.