diff --git a/model/src/w3gridmd.F90 b/model/src/w3gridmd.F90
index fa8128afb..f700dede8 100644
--- a/model/src/w3gridmd.F90
+++ b/model/src/w3gridmd.F90
@@ -2962,6 +2962,7 @@ SUBROUTINE W3GRID()
       CALL EXTCDE( 31)
     ENDIF
 
+    USSP_WN = 0.0 ! initialize to 0s
     DO J=1,USSPF(2)
       USSP_WN(j) = STK_WN(J)
     ENDDO