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• the background error estimate still appears too small in the lowest levels although stochastic physics in Cycle 49r1 have partially addressed this.  A larger spread of error estimates near the surface would tend to increase the size of analysis increments from T2m assimilation at the lowest model level and to reduce them a few levels up.  This would be more realistic for winter cases.

In general:

• actual and model station altitude in mountainous areas may differ.
• strong surface inversions, particularly over snow, may not be well modelled.
• extent of low cloud cover may not be captured by the model.

Users should assess the potential for deficiencies in low-level parameters and adjust forecast values as necessary.

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