New York to LA via North Bay

From the FAA web site:

Flying North for the Summer

July 29 – Summer thunderstorms cause roughly 70% of all delays. The FAA’s Air Traffic Control System Command Center in Herndon, Virginia uses Canadian routes to spread out traffic and rebalance the workload within the national airspace system during these thunderstorms. Canadian routes allow U.S. air traffic controllers to safely expedite the flow of air traffic through the extra airspace, which reduces the backlash of delays during severe weather.

In order for New York traffic to safely get around thunderstorms blocking routes to the south and west of the metropolitan area, controllers direct planes through Canadian routes that extend as far north as North Bay, Ontario and Sault Ste. Marie, Michigan.

Decisions to use the routes are made jointly with Canadian air traffic control. The U.S. and Canada routinely participate in each other’s air traffic control planning teleconferences.

As a rule, the agency tries to provide several hours of advance notice when it sees a need for the Canadian routes. However, there are times when thunderstorms materialize unexpectedly or in places not previously forecast, and our neighbors to the north are quick to provide help and traffic relief.