Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

According to the model data 2013 has peaked at a total volume of 21,823 km3 on April 17th, which is 100 km3 below last year's record. Since then, 2013 volume has dipped quite a bit below last year's number (295 km3 to be precise), but is still close to 2011 which has only 63 km3 more at this moment.

Here is Wipneus' version with the calculated "expected" 2013 values (dotted lines), based on the same date values of 1979-2011 and an exponential trend.

A caveat from Wipneus: "Note that the statistical error bars are quite large."