Thursday’s Ask Storm Team 11 question comes from Lawrence Weaver. Lawrence asked, “Why do tornadoes go east northeast and hurricanes go west northwest.”
The direction of tornadoes and hurricanes is based on synoptic scale, or large weather systems.
As low pressure systems travel generally eastward, they carry warm and cold fronts in the same general direction as the jet stream. Conditions becomes favorable in between these fronts for severe weather, especially during the spring. Tornadoes form in severe thunderstorms. The storms follow the direction of these systems. This is why tornadoes generally travel from southwest to northeast.
Zooming out to the overall pattern, you may know our jet stream travels from west to east. But near the equator, the trade winds flow mainly towards the west. This is why in the tropics, systems form in the east and move towards the west. Now what gives tropical systems a turn northward? Another synoptic scale system is a high pressure. We call this steering current in the Atlantic the Bermuda High. As winds spin clockwise, the tropical system will follow the wind currents around the high and eventually northward. When the system makes that turn, just how sharp and when depends on the strength and location of the Bermuda High.
Ask Storm Team 11 your questions!