Polar stereographic projection contourf leaves small area blank

Dear all,

when trying to contourf data from a netCDF file in North-Polar
Stereographic projection, I encounter the problem that the map is not
filled completely but there is a gap between 0E and some -2E where the
map stays blank (see attached plot).

I am reading the grid (lon,lat) from the respective netCDF file
variables. When plotting with other software, e.g. Ferret or Panoply,
the problem does not occur. The essential code:

import numpy as np
from netCDF4 import Dataset
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import matplotlib.spines

# what to plot
varclevs={ # contour levels for the given variable
    'slp': np.arange(-200,101,25),
    'temp2': np.arange(-3,3.5,.5)}
varlabel={ # variable labels
    'slp': 'sea level pressure anomaly [Pa]',
    'temp2': '2m air temperature anomaly [K]'}
varcmap={ # color map to use for variable
    'slp': plt.cm.RdYlBu_r,
    'temp2': plt.cm.Spectral}

# paths
dataDir = '...'
plotDir = '...'

# Open file and read data
fname = dataDir + anom+'_ensmean.JASmean.'+var+'.nc'
ncf = Dataset(fname)
vardata = ncf.variables[var][:]
lons = ncf.variables['lon'][:]
lats = ncf.variables['lat'][:]

# Map projection
m = Basemap(projection='npstere',boundinglat=60,lon_0=-30,resolution='l')

# make coordinate grid for contour plot
xx,yy = m(*np.meshgrid(lons,lats))

# Plot stuff
# set plot
f = plt.figure()
ax = plt.gca()

# draw coast lines etc

# draw parallels and meridians.

# label parallels manually
for l in range(len(latvals)):
    latval = latvals[l]
    lonval = lonvals[l]
    x,y = m(lonval,latval)
    latlab = '{0} N'.format(latval)

# plt.xlabel('longitude')
# plt.ylabel('latitude')

# Contour data
datacntr = m.contourf(xx,yy,vardata[0,:,:],

# draw color bar
datacb = plt.colorbar(datacntr,orientation='vertical',shrink=1.)

I am using the Entought Python Distribution 7.0 on Mac OS X 10.5.
Thanks for your kind help!

Jonas B., GFI, Bergen, Norway

npstere_contourf_problem.pdf (252 KB)