anchor.diff:      !! @param   [inout]current_precip   accumulated model precip at this time step
       !! @param   [in]last_precip         accumulated model precip prior to microphysics call
       !! @param   [in]local_fraction      fraction of precip to maintain in the local gridcell
  +    !! @param   [in]precip_delta        Flag to calculate this time steps precip as a delta from previous
       !!
       !!----------------------------------------------------------
  -    subroutine distribute_precip(current_precip, last_precip, local_fraction)
  +    subroutine distribute_precip(current_precip, last_precip, local_fraction, precip_delta)
           real, dimension(:,:), intent(inout) :: current_precip, last_precip
           real, intent(in) :: local_fraction
  +        logical, intent(in) :: precip_delta
           ! relies on module variable this_precip as a temporary array
           
           integer :: i,j, nx,ny
  
positive.code:                            )
              endif
              
              if ((options%mp_options%local_precip_fraction<1).and.(options%physics%microphysics/=kMP_MORRISON) ) then
                  call distribute_precip(domain%rain, last_rain, options%mp_options%local_precip_fraction)
                  call distribute_precip(domain%snow, last_snow, options%mp_options%local_precip_fraction)
              endif
          endif
          
  
negative.code:         if (options%physics%microphysics==kMP_THOMPSON) then
              write(*,*) "    Thompson Microphysics"
              call thompson_init(options%mp_options)
              precip_delta=.True.
          elseif (options%physics%microphysics==kMP_SB04) then 
              write(*,*) "    Simple Microphysics"
              precip_delta=.True.
          elseif (options%physics%microphysics==kMP_MORRISON) then 
              write(*,*) "    Morrison Microphysics"
              call MORR_TWO_MOMENT_INIT(hail_opt=0)
              precip_delta=.False.
          endif
  
          update_interval = options%mp_options%update_interval
  