diff --git a/config_src/external/drifters/MOM_particles.F90 b/config_src/external/drifters/MOM_particles.F90
index 95470e6510..1c41170582 100644
--- a/config_src/external/drifters/MOM_particles.F90
+++ b/config_src/external/drifters/MOM_particles.F90
@@ -28,7 +28,7 @@ subroutine particles_init(parts, Grid, Time, dt, u, v, h)
 end subroutine particles_init
 
 !> The main driver the steps updates particles
-subroutine particles_run(parts, time, uo, vo, ho, tv, use_uh, stagger)
+subroutine particles_run(parts, time, uo, vo, ho, tv, dt_adv, use_uh)
   ! Arguments
   type(particles), pointer :: parts !< Container for all types and memory
   type(time_type), intent(in) :: time !< Model time
@@ -40,8 +40,8 @@ subroutine particles_run(parts, time, uo, vo, ho, tv, use_uh, stagger)
                                            !! that are used to advect tracers [H L2 ~> m3 or kg]
   real, dimension(:,:,:), intent(in) :: ho !< Ocean layer thickness [H ~> m or kg m-2]
   type(thermo_var_ptrs),  intent(in) :: tv !< structure containing pointers to available thermodynamic fields
+  real, intent(in) :: dt_adv !< timestep for advecting particles [s]
   logical :: use_uh !< Flag for whether u and v are weighted by thickness
-  integer, optional, intent(in) :: stagger !< Flag for whether velocities are staggered
 
 end subroutine particles_run
 
diff --git a/src/core/MOM.F90 b/src/core/MOM.F90
index e5d1f46086..8cfab91cfc 100644
--- a/src/core/MOM.F90
+++ b/src/core/MOM.F90
@@ -1283,6 +1283,18 @@ subroutine step_MOM_dynamics(forces, p_surf_begin, p_surf_end, dt, dt_thermo, &
 
   endif ! -------------------------------------------------- end SPLIT
 
+  if (CS%use_particles .and. CS%do_dynamics .and. (.not. CS%use_uh_particles)) then
+    if (CS%thickness_diffuse_first) call MOM_error(WARNING,"particles_run: "//&
+      "Thickness_diffuse_first is true and use_uh_particles is false. "//&
+      "This is usually a bad combination.")
+    !Run particles using unweighted velocity
+    call particles_run(CS%particles, Time_local, CS%u, CS%v, CS%h, &
+                       CS%tv, dt, CS%use_uh_particles)
+    call particles_to_z_space(CS%particles, h)
+  endif
+
+
+
   ! Update the model's current to reflect wind-wave growth
   if (Waves%Stokes_DDT .and. (.not.Waves%Passive_Stokes_DDT)) then
     do J=jsq,jeq ; do i=is,ie
@@ -1368,23 +1380,21 @@ subroutine step_MOM_dynamics(forces, p_surf_begin, p_surf_end, dt, dt_thermo, &
   endif
   call disable_averaging(CS%diag)
 
+  ! Advance the dynamics time by dt.
+  CS%t_dyn_rel_adv = CS%t_dyn_rel_adv + dt
+
   if (CS%use_particles .and. CS%do_dynamics .and. CS%use_uh_particles) then
     !Run particles using thickness-weighted velocity
     call particles_run(CS%particles, Time_local, CS%uhtr, CS%vhtr, CS%h, &
-        CS%tv, CS%use_uh_particles)
-  elseif (CS%use_particles .and. CS%do_dynamics) then
-    !Run particles using unweighted velocity
-    call particles_run(CS%particles, Time_local, CS%u, CS%v, CS%h, &
-                       CS%tv, CS%use_uh_particles)
+        CS%tv, CS%t_dyn_rel_adv, CS%use_uh_particles)
   endif
 
-
-  ! Advance the dynamics time by dt.
-  CS%t_dyn_rel_adv = CS%t_dyn_rel_adv + dt
   CS%n_dyn_steps_in_adv = CS%n_dyn_steps_in_adv + 1
   if (CS%alternate_first_direction) then
     call set_first_direction(G, MODULO(G%first_direction+1,2))
     CS%first_dir_restart = real(G%first_direction)
+  elseif (CS%use_particles .and. CS%do_dynamics .and. (.not.CS%use_uh_particles)) then
+    call particles_to_k_space(CS%particles, h)
   endif
   CS%t_dyn_rel_thermo = CS%t_dyn_rel_thermo + dt
   if (abs(CS%t_dyn_rel_thermo) < 1e-6*dt) CS%t_dyn_rel_thermo = 0.0