C NCLFORTSTART
      SUBROUTINE MYINTERP(V3D,V2D,Z,SFC,NX,NY,NZ)
      IMPLICIT NONE
      INTEGER NX,NY,NZ
      DOUBLE PRECISION V3D(NX,NY,NZ),V2D(NX,NY) ! This used to be DOUBLE PRECISION
      DOUBLE PRECISION Z(NX,NY,NZ)
      DOUBLE PRECISION SFC(NX,NY)
C NCLEND
      INTEGER I,J,KP,IP,IM
      LOGICAL INTERP
      DOUBLE PRECISION HEIGHT,W1,W2

c does vertical coordinate increase or decrease with increasing k?
c set offset appropriately

      IP = 0
      IM = 1
      IF (Z(1,1,1).GT.Z(1,1,NZ)) THEN
          IP = 1
          IM = 0
      END IF

      DO I = 1,NX
          DO J = 1,NY
C Initialize to missing.  Was initially hard-coded to -999999.
              INTERP = .false.
              KP = NZ

              DO WHILE ((.NOT.INTERP) .AND. (KP.GE.2))
                  HEIGHT=SFC(I,J)
                  IF (((Z(I,J,KP-IM).LE.HEIGHT).AND. (Z(I,J,
     +                KP-IP).GT.HEIGHT))) THEN
                      W2 = (HEIGHT-Z(I,J,KP-IM))/
     +                     (Z(I,J,KP-IP)-Z(I,J,KP-IM))
                      W1 = 1.D0 - W2
                      V2D(I,J) = W1*V3D(I,J,KP-IM) + W2*V3D(I,J,KP-IP)
                      INTERP = .true.
                  END IF
                  KP = KP - 1

              END DO

          END DO
      END DO

      RETURN
      END