diff --git a/ush/parsing_namelists_FV3.sh b/ush/parsing_namelists_FV3.sh
index b88849d7e78..dfbdfcbc856 100755
--- a/ush/parsing_namelists_FV3.sh
+++ b/ush/parsing_namelists_FV3.sh
@@ -387,7 +387,7 @@ cat >> input.nml <<EOF
   iopt_tbot    = ${iopt_tbot:-"2"}
   iopt_stc     = ${iopt_stc:-"1"}
   iopt_trs     = ${iopt_trs:-"2"}
-  iopt_diag    = ${iopt_diag:-"1"}
+  iopt_diag    = ${iopt_diag:-"2"}
   debug        = ${gfs_phys_debug:-".false."}
   nstf_name    = ${nstf_name}
   nst_anl      = ${nst_anl}
diff --git a/ush/parsing_namelists_FV3_nest.sh b/ush/parsing_namelists_FV3_nest.sh
index 2f99a1cdf56..40ab80afcdb 100755
--- a/ush/parsing_namelists_FV3_nest.sh
+++ b/ush/parsing_namelists_FV3_nest.sh
@@ -444,7 +444,7 @@ cat >> "${nml_file}" <<EOF
   iopt_tbot    = ${iopt_tbot:-"2"}
   iopt_stc     = ${iopt_stc:-"1"}
   iopt_trs     = ${iopt_trs:-"2"}
-  iopt_diag    = ${iopt_diag:-"1"}
+  iopt_diag    = ${iopt_diag:-"2"}
   debug        = ${gfs_phys_debug:-".false."}
   nstf_name    = ${nstf_name}
   nst_anl      = ${nst_anl}