Index: /issm/trunk/src/m/model/extrude.m
===================================================================
--- /issm/trunk/src/m/model/extrude.m	(revision 8317)
+++ /issm/trunk/src/m/model/extrude.m	(revision 8318)
@@ -153,5 +153,5 @@
 md.dhdt=project3d(md,md.dhdt,'node');
 md.firn_layer=project3d(md,md.firn_layer,'node',md.numlayers);
-md.forcing_accumulation=[project3d(md,md.forcing_accumulation(1:end-1,:),'node');md.forcing_accumulation(end,:)];
+if ~isnan(md.forcing_accumulation), md.forcing_accumulation=[project3d(md,md.forcing_accumulation(1:end-1,:),'node');md.forcing_accumulation(end,:)]; end
 
 %results