The Westerlies, anti-trades, or Prevailing Westerlies, are
prevailing winds in the middle latitudes between 30 and 60
degrees latitude, blowing from the high pressure area in the
horse latitudes towards the poles. These prevailing winds blow
from the west to the east and steer extratropical cyclones in
this general manner. Tropical cyclones which cross the
subtropical ridge axis into the Westerlies recurve due to the
increased westerly flow. The winds are predominantly from the
southwest in the Northern Hemisphere and from the northwest in
the Southern Hemisphere. The Westerlies are strongest in the
winter hemisphere and times when the pressure is lower over the
poles, while they are weakest in the summer hemisphere and when
pressures are higher over the poles. The Westerlies are
particularly strong, especially in the southern hemisphere,
where there is less land in the middle latitudes to cause the
flow pattern to amplify, or become more north-south oriented,
which slows the Westerlies down. The strongest we