County average using shape files

Hello,
I am having trouble calculating the US county area averages using gridded
CONUS data and US county shape file data. The county polyline overlay
works, but I cannot get the county area average function to work with my
data.
Following the example script
www.ncl.ucar.edu/Applications/Scripts/shapefiles_13.ncl
I am getting the following error:

fatal: Subscript out of range, error in subscript #0
fatal: An error occurred reading skip_check

;The CONUS data is land only for the coterminous US:

hf1 = addfile("conus.nc","r")
data = hf1->tmaxhist(:,:) ; ((/nlat,nlon/),float)
lat = hf1->lat
lon = hf1->lon

; The attributes of data and lat/lon are as follows:
; nlat = 222
; nlon = 462
; minlat/maxlat = 25.1875/52.8125
; minlon/maxlon = 235.312/292.938
; lat@units = "degrees_north"
; lon@units = "degrees_east"


Any help would be much appreciated. Thank you.
--
Cary Lynch

Received on Tue Jul 01 05:21:23 2014