Update: Here are the specs…

Apple is preparing to launch a refreshed line of MacBook Air laptops as soon as tomorrow, according to multiple sources. These sources say that shipments of new MacBook Airs have begun arriving in large quantities to Apple Stores across the country. Another source adds that Apple Stores are scheduled to re-arrange the placement of Macs in stores to focus on the MacBook Air tomorrow morning…

While a milestone MacBook Air update with a thinner profile, no fan, and a Retina display is in the works, tomorrow’s update is not that computer. Tomorrow’s 11-inch and 13-inch Airs are codenamed J41A and J43A, respectively, and their SKUs are simply a variation to the current MacBook Air SKU labels. For example, the entry 13-inch MacBook Air of today is known as “MD760LL/A”, while this week’s refreshed version is known as “MD760LL/B.” It’s unclear if Apple will even promote the updated Airs.

Tomorrow’s update will probably focus on adding Intel’s latest Haswell chips. These processors offer minor speed increases, and Apple will likely tweak the Air’s storage options to round-out the update. An earlier rumor indicated that new MacBook Airs could arrive this week. We’ll have additional details on this minor MacBook Air refresh as they come in, so stay tuned.