diff --git a/.gitmodules b/.gitmodules
index e1ad81bb1..a9b719bb8 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,7 +1,9 @@
 [submodule "atmos_cubed_sphere"]
   path = atmos_cubed_sphere
-  url = https://github.com/NOAA-EMC/GFDL_atmos_cubed_sphere
-  branch = production/RRFS.v1
+#  url = https://github.com/NOAA-EMC/GFDL_atmos_cubed_sphere
+#  branch = production/RRFS.v1
+  url = https://github.com/DusanJovic-NOAA/GFDL_atmos_cubed_sphere
+  branch = rrfs_v1_conus13km_tests
 [submodule "ccpp/framework"]
   path = ccpp/framework
   url = https://github.com/NCAR/ccpp-framework
diff --git a/atmos_cubed_sphere b/atmos_cubed_sphere
index 84c30284b..405ca88fe 160000
--- a/atmos_cubed_sphere
+++ b/atmos_cubed_sphere
@@ -1 +1 @@
-Subproject commit 84c30284b2a1e7efb4c6ef9c05566c1a27d1a8fd
+Subproject commit 405ca88fefcda09d1158652970fbc023a66af145
diff --git a/module_fcst_grid_comp.F90 b/module_fcst_grid_comp.F90
index ea622369c..77ca8c1b8 100644
--- a/module_fcst_grid_comp.F90
+++ b/module_fcst_grid_comp.F90
@@ -59,7 +59,9 @@ module module_fcst_grid_comp
   use fv3atm_restart_io_mod,  only: fv_phy_restart_bundle_setup, fv_sfc_restart_bundle_setup
   use fv_ufs_restart_io_mod,  only: fv_core_restart_bundle_setup, &
                                     fv_srf_wnd_restart_bundle_setup, &
-                                    fv_tracer_restart_bundle_setup
+                                    fv_tracer_restart_bundle_setup, &
+                                    fv_diag_restart_bundle_setup
+  use module_diag_hailcast,   only: do_hailcast
 
   use fms2_io_mod,        only: FmsNetcdfFile_t, open_file, close_file, variable_exists, read_data
 
@@ -361,6 +363,9 @@ subroutine init_dyn_fb(nest, importState, exportState, clock, rc)
     else if (fb_name(1:21) == 'restart_fv_tracer.res') then
       call fv_tracer_restart_bundle_setup(fbList(1), grid, rc=rc)
       if (ESMF_LogFoundError(rcToCheck=rc, msg=ESMF_LOGERR_PASSTHRU, line=__LINE__, file=__FILE__)) return
+    else if (fb_name(1:19) == 'restart_fv_diag.res') then
+      call fv_diag_restart_bundle_setup(fbList(1), grid, rc=rc)
+      if (ESMF_LogFoundError(rcToCheck=rc, msg=ESMF_LOGERR_PASSTHRU, line=__LINE__, file=__FILE__)) return
     else
       do i=1, itemCount
         call fv_dyn_bundle_setup(Atmos%axes, fbList(i), grid, quilting=.true., rc=rc)
@@ -581,6 +586,11 @@ subroutine fcst_initialize(fcst_comp, importState, exportState, clock, rc)
     logical,allocatable           :: is_moving_on_all_pets(:), is_moving(:)
     character(len=7)              :: nest_suffix
 
+    integer, parameter            :: MAX_NUM_DYN_BUNDLES = 10
+    character(len=esmf_maxstr), dimension(MAX_NUM_DYN_BUNDLES) :: dyn_bundles_name
+
+    integer                       :: num_dyn_bundles = 0
+
     type(FmsNetcdfFile_t)         :: fileobj
 !
 !-----------------------------------------------------------------------
@@ -1055,21 +1065,24 @@ subroutine fcst_initialize(fcst_comp, importState, exportState, clock, rc)
 
         if ( quilting_restart ) then
 
-          do i=1,3 ! 3 dynamics restart bundles
+          ! Number of non-optional dyn bundles (core, srf_wnd and tracer)
+          num_dyn_bundles = 3
+          dyn_bundles_name(1) = 'restart_fv_core.res'
+          dyn_bundles_name(2) = 'restart_fv_srf_wnd.res'
+          dyn_bundles_name(3) = 'restart_fv_tracer.res'
+
+          ! Optional dyn bundles
+          if (do_hailcast) then
+             num_dyn_bundles = num_dyn_bundles + 1
+             dyn_bundles_name(num_dyn_bundles) = 'restart_fv_diag.res'
+          end if
+
+          do i=1,num_dyn_bundles ! dynamics restart bundles
 
             tempState = ESMF_StateCreate(rc=rc)
             if (ESMF_LogFoundError(rcToCheck=rc, msg=ESMF_LOGERR_PASSTHRU, line=__LINE__, file=__FILE__)) return
 
-            if (i == 1) then
-              name_FB = 'restart_fv_core.res'
-            elseif (i == 2) then
-              name_FB = 'restart_fv_srf_wnd.res'
-            elseif (i == 3) then
-              name_FB = 'restart_fv_tracer.res'
-            else
-              write(0,*)' unknown name_dynamics restart bundle ', i
-              ESMF_ERR_ABORT(101)
-            endif
+            name_FB = dyn_bundles_name(i)
 
             if (n > 1) then
               write(nest_suffix,'(A5,I2.2)') '.nest', n