The new 2013 MacBook Air looks exactly like the 2012 model, but lurking beneath the surface of Apple’s latest, thinnest notebook are several significant internal changes. Courtesy / Apple.com

Apple Inc. (Nasdaq:AAPL) will launch a refreshed line of its ultraportable notebook, the Macbook Air, as soon as Tuesday. According to 9to5Mac, multiple reliable sources say that MacBook Air shipments began arriving at Apple retail stores around the United States recently. However, if you’re looking to get the next MacBook Air, this most likely is not it.

"The new MacBook Air 11-inch and 13-inch models are codenamed J41A and J43A, respectively, and their SKUs are simply a variation on current MacBook Air SKU labels. For example, the current entry-level 13-inch MacBook Air is known as "MD760LL/A", while the new shipments' version is known as "MD760LL/B." It's unclear if Apple will even promote the updated Airs." – 9to5Mac

The news comes a week after French site MacG suggested that the MacBook Air would see a minor refresh this week. The computer that will hit shelves on Tuesday is just an updated version of the current model, which will come in both an 11-inch and a 13-inch version. These new models will most likely possess the latest Haswell chips from Intel, adding a bump to the processing speed, and a possibly larger SSD. But the new models likely won't have a thinner chassis or a Retina display.

Apple will most likely announce a major update to the Air line at the World Wide Developers Conference (WWDC) in June. KGI Securities analyst Ming-Chi Kuo, noted for his historically accurate predictions, recently suggested that the next major update to the Macbook Air line will come later this year, in Q3. Kuo said to look for a Retina display around 12-inches in size, a thinner and lighter clamshell design, a fan-less unibody, and the Haswell chipset. He also speculated on a potentially lower cost model compared to current Apple notebooks.

The back of the refreshed MacBook Air, showing a faster processor. Courtesy 9to5Mac

Update: According to an image procured by 9to5Mac, much of what was speculative is now confirmed. The image is indeed for the new 13-inch MacBook Air, which will possess the new Haswell chipset. The lightweight computer will now have a 1.4GHz Intel Core i5 processor with Turbo Boost up to 2.7GHz, which will give it an across-the-board increase in speed. Current MacBook Air models have a 1.3GHz i5 with Turbo Boost up to 2.6GHz. Everything else remains consistent overall, meaning that the next major update will most likely include the Retina display and a lighter chassis.

As more information becomes available, this story will be updated.