diff --git a/src/MNH/read_all_data_grib_case.f90 b/src/MNH/read_all_data_grib_case.f90
index 841ae62b0c834902a5fec42fcbbac2c947e6d8c3..04a8ff5e8b5556152d2a61599a05cbe5ed0c25ef 100644
--- a/src/MNH/read_all_data_grib_case.f90
+++ b/src/MNH/read_all_data_grib_case.f90
@@ -1480,6 +1480,7 @@ END IF
 ! After this projection, the file is simil
 !
 IF (HFILE(1:3)=='ATM') THEN
+ISTARTLEVEL = 1
 ALLOCATE (XU_LS(IIU,IJU,INLEVEL))
 ALLOCATE (XV_LS(IIU,IJU,INLEVEL))
 ALLOCATE (ZTU_LS(INO))