Voordelen & nadelen ECMWF, UKMO en GFS

• Compared to the other 2 operational models described above, the ECMWF does the best in predicting mid/upper tropospheric heights during the colder part of the year(such as October through April). The ECMWF tends to perform quite well in predicting amplitudes of planetary-scale regimes such as the Pacific/North American teleconnection (PNA). This model can also perform outstandingly during low to high planetary-scale wavenumber transition events, and northern hemispheric-scale regime transitions (Berry et al. 1996, CR TM 111).


• Outperforms the other medium-range forecast models during shallow cold air situations.


• Tends to overdevelop mid/upper cyclones across the southwestern U.S. Situations arise where this model will be too slow to predict the movement of cyclones from the southwest deserts.


• Has a slight tendency to forecast mid/upper tropospheric heights and the resultant thickness calculations too high (i.e.; a warm bias).


• Sometimes, especially during the warmer portion of the annual cycle, this model has too many closed lows. This bias may be related to its high resolution.


• Tends to overamplify the long wave pattern, resulting in slower than observed progression of systems through the westerlies. This can result in overly weak and northward displaced short waves and associated surface features lifting into the long wave ridge position.


• Found to have the smallest overall distance errors with springtime closed low forecasts during days four and five.


• Westward forecast bias of closed cyclones (related to the issue described above)


• Often too slow moving short wave features in deamplifying or zonal patterns


• Of the medium range models, the ECMWF performs best with driving Arctic fronts down the east slopes of the Rockies.


• The ECMWF too often incorrectly digs closed upper lows SWWD then WWD underneath strong upper ridges over the Eastern Pacific.

• Has problems with shallow cold air.


• Tends to progress shorter wavelength features too quickly.


• Westerlies are often too far south.


• The model tends to lower surface pressures too much and too far south and often implies synoptic-scale fronts too far south.


• Often too low with heights along the southern ends of short wave trofs, resulting in a southward displaced storm track


• Significant low pressure bias during the warm season over the western U.S., particularly when upper ridge conditions predominate


• Breaks down amplified long wave patterns too quickly


• Over the east, tends to be too weak and strung out with surface cyclogenesis along fronts when a significant short wave is digging into the trough position. This results from the forecasted baroclinic zone being too broad and low-level temperature gradients being too weak. (Doesn't take into account latent heat release from
  the Gulf Stream).


• Of the medium range models, it has the poorest performance forecasting polar vortices.


• Often is too flat with the upper and surface patterns over the western Pacific.


• Eastward forecast bias with upper lows, especially over eastern Canada, possibly due to its tendency to flatten amplified patterns too quickly


• The UKMET often develops an upper system too far to the south over the Gulf of Mexico and the northwest Caribbean. This is a tropical interaction problem or applies directly to tropical cyclones.