To aid in this and with forecasting along ship routes, the model has also been required to perform well in cases of oceanic midlatitude cyclogenesis. This section will discuss some of the model tendencies which have been noted by Navy forecasters and other investigators of the model. Please note that many of the other global numerical models suffer from similar tendencies. Developing surface low pressure systems tend to develop slower in the model than in reality. Filling low-pressure systems also tend to be slower to fill then in reality.
Secondary lows are also slow to develop, deepen, and move.
Low-pressure systems north of the polar jet tend to deepen too much, while lows developing south of the polar jet are typically too weak and slow to deepen. Surface low-pressure systems over land have a tendency to be slightly too deep. Complex lows are usually merged into one elongated low-pressure system. In this situation the mature low-pressure system tends to be too deep and slow to fill, while the developing low is weak, too slow to weaken, and too slow to move. Upper-level shortwave troughs embedded in either zonal flow or a broad trough are poorly forecast and difficult to follow.