Apple is overdue for a refresh of its popular MacBook Pro product line, and recent checks indicate that a new model may come as early as March.

Supplies of MacBook Pro's in distribution channels are thinning, with roughly two weeks of units available versus six weeks, according to Kaufman analysts Shaw Wu.

He believes strong demand could play a factor, but also believes that the inventory is intentionally being worked down in preparation for a new MacBook Pro.

We believe new Mac models could ship in the March quarter, or at the latest the June quarter, Wu said. It is not clear to us whether AAPL will  introduce these new Macs through a special event or quietly through a press release.

Apple's laptops come in a regular version, targeting most consumers, while its 'Pro' line is aimed at power-users and professionals needing more computing power.

The line between the high-end Macbook and the Pro version is beginning to thin, however, which analysts believes necessitates the need for an update further.

On the surface, the Mac business doesn't really need a refresh due to its strong momentum, said Kaufman analyst Shaw Wu, but we believe a refresh of the MacBook Pro makes sense to keep the product fresh.

Apple last refreshed the Pro series laptop in June 2009, while the normal Macbook got updates in October 2009.

[More] differentiation beyond the aluminum casing, SD slot and FireWire can help the MacBook Pro preserve its premium pricing, Wu explained.

It is possible that the new notebooks will feature Intel's next-generation mobile processor, codenamed Arrandale, which Wu said would give Apple engineers more room to differentiate the Pro series.