Atlantic mature lows are mostly deep and slow to fill. Mature oceanic lows are usually to the left of the analysis track and only occasionally to the right of the analysis track at the extended forecast period in strong upper-level flow. Former West Pacific tropical cyclones are typically slow to move during and after transition to extratropical. Secondary cyclogenesis continues to be under-forecast. Lee cyclogenesis off Southeast Kamchatka and Greenland is under-forecast.
Surface lows forming south of the polar jet and bottom-up types of lows are slow to deepen.
These are usually mature lows that have bottomed-out and tend to be slow to fill. The tendency to over-deepen lows is mostly observed in the cool seasons. Sea-level pressure analyses and forecasts over the very high terrain of Greenland, the Himalayas, and Antarctica are suspect and should be used with caution. In the deepening stage, forecast tropical cyclone directional bias is behind the analysis track and slow to move. After reaching maximum intensity, mature tropicals continue to be slow to move.