You need to think bigger: What if it got below 12 million by April 30?
I expect below 12 million by April 30th is almost certain.
Anything below 12.5 by April 30th is highly unlikely. The only areas likely to melt significantly before then are Okhotsk and Bering There is only about 1M km^2 in those areas and they are unlikely to totally melt out. None of the other areas are likely to see significant losses before May.
The whole Arctic ocean may be primed for major losses after May but they are unlikely to start occurring before May.
Well, to be sure, the rest of April would have to see record small daily losses to finish above 12.5 million; every April for the past decade saw enough decrease from the 11th through the 30th that, if repeated this year, would result in a finish for the month of about 12.3 million. But you are correct that a sub-12 million reading is pretty unlikely.
The bottleneck is the end of May when the std deviation for extent distribution is at its lowest.
Although it would require record low daily losses to stay above 12.5 there is a clear pattern where the lower the starting value in April the smaller the decline. Of the years that started April above 14M only 2011 had a decline that would take us to below 12.3 and it started at 13.96.
Most of the remaining ice that is not in the Pacific is nearly landlocked or so far north that it will take a while for warming to reach here. We are not talking about free floating ice like that around the Antarctic where the heat can just keep moving towards the land. In the Arctic the movement of warmer water is constrained by the land barriers so the decline is not smooth.
You're referring to NSIDC, correct? So far as IJIS, of the years that began April above 14 million--'08, '09, '10, '11, and '12--all but 2009 had declines that would leave 2016 above 12.3 at the end of the month. On the other hand, of the years that began April below 14 million--'06, '07, 13, '14, and '15--only a repeat of 2013 would result in a sub-12.3 April finish. However, a repeat of any year in the past decade would result in a sub-12.5 finish, which is the original point to which I was responding.
At any rate--and again--this is going to be an interesting melt season...