diff --git a/.gitmodules b/.gitmodules
index 5ece87098e..857ca868ef 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,7 +1,9 @@
 [submodule "FV3"]
   path = FV3
-  url = https://github.com/NOAA-EMC/fv3atm
-  branch = develop
+  #url = https://github.com/NOAA-EMC/fv3atm
+  #branch = develop
+  url = https://github.com/junwang-noaa/fv3atm
+  branch = reg3km_decomp
 [submodule "WW3"]
   path = WW3
   url = https://github.com/NOAA-EMC/WW3
diff --git a/FV3 b/FV3
index e2d12a8de5..12b0655691 160000
--- a/FV3
+++ b/FV3
@@ -1 +1 @@
-Subproject commit e2d12a8de5d0bacb10d138adaaf948e28ca34ac8
+Subproject commit 12b06556916da7cca2b6aa6f7717acb56790b70d
diff --git a/tests/rt.conf b/tests/rt.conf
index e4777861c9..3778036e18 100644
--- a/tests/rt.conf
+++ b/tests/rt.conf
@@ -63,6 +63,7 @@ RUN     | regional_noquilt
 RUN     | regional_2threads                                                                                                       | - wcoss_cray jet.intel                  |     |
 RUN     | regional_netcdf_parallel                                                                                                |                                         | fv3 |
 RUN     | regional_3km                                                                                                            |                                         | fv3 |
+RUN     | regional_3km_decomp                                                                                                     |                                         |     |
 
 COMPILE | -DAPP=ATM -DCCPP_SUITES=FV3_RAP,FV3_RAP_RRTMGP,FV3_RAP_sfcdiff,FV3_HRRR,FV3_HRRR_smoke,FV3_RRFS_v1beta,FV3_RRFS_v1nssl -D32BIT=ON      |                                         | fv3 |
 
diff --git a/tests/tests/regional_3km_decomp b/tests/tests/regional_3km_decomp
new file mode 100644
index 0000000000..8a3a61e152
--- /dev/null
+++ b/tests/tests/regional_3km_decomp
@@ -0,0 +1,46 @@
+###############################################################################
+#
+#  FV3 regional hi-res 3km test with different decomposition
+#
+###############################################################################
+
+export TEST_DESCR="Compare FV3 decomposition regional hi-res 3km results with previous trunk version"
+
+export CNTL_DIR=fv3_regional_3km
+
+export LIST_FILES="dynf000.nc \
+                   dynf006.nc \
+                   phyf000.nc \
+                   phyf006.nc \
+                   PRSLEV.GrbF00 \
+                   PRSLEV.GrbF06 \
+                   NATLEV.GrbF00 \
+                   NATLEV.GrbF06"
+
+export_fv3
+
+export FV3_RUN=regional_3km_run.IN
+
+export OZ_PHYS_OLD=.false.
+export OZ_PHYS_NEW=.true.
+export H2O_PHYS=.true.
+export HYBEDMF=.false.
+export RESTART_INTERVAL="0"
+export WRITE_DOPOST=.true.
+export POSTAPP='lam'
+
+export CCPP_SUITE=FV3_GFS_v15_thompson_mynn_lam3km
+export INPUT_NML=regional_3km.nml.IN
+export MODEL_CONFIGURE=model_configure_regional_3km.IN
+export DIAG_TABLE=diag_table_lam
+export FIELD_TABLE=field_table_regional
+
+export WLCLK=15
+export FHMAX=6
+export TASKS=120
+export INPES=11
+export JNPES=10
+export OUTPUT_FH="3 -1"
+WRITE_GROUP=1
+WRTTASK_PER_GROUP=10
+NTILES=1