After reaching maximum intensity, mature tropicals continue to be slow to move. Mid-ocean high cells tend to be 1 to 2 mb strong by 48 to 72 hours. The forecast central pressure of the offshore Eastern Pacific high cell is also somewhat strong. Upper level short-wave troughs in strong zonal and broad meridional flow are slightly weak. The associated developing surface low tends to be slow to deepen and 3 to 4 mb weak.
Upper level lows north of the polar jet tend to be deep.
Upper level highs south of the polar jet are slightly strong. The formation of upper level cut-off lows associated with a digging trough continues to be well forecast in the transition seasons. Splitting upper level troughs moving in zonal flow typically show the poleward portion to be well defined, but too deep. The equatorward portion of the trough is less defined and typically underforecast. Intense jet level winds may be underforecast due to the limited vertical resolution of the model.