November is the month of the short rains, but it is not so easy to time when they actually begin. In some years, rainfalls are abundant as early as mid-October and sometimes they arrive later.
The time the rains start and their abundance considerably affect the movement of the Great Migration. If the rainfalls are late or insufficient to fill the ponds and seasonal torrents in the Southern Serengeti and the Ngorongoro Conservation Area, the herds are reluctant to leave the Maasai Mara pastures and the Northern Serengeti as they know they will not find the grassy and fertile pastures they need.  Instead, if the rainfalls are so heavy to fill the ponds and seasonal torrents, the Great Migration sets off. 
The animals walk one after the other, in columns as long as the eye can see. In 40-50 kms long rows, wildebeests and zebras head to the Central and Southern part of the Serengeti, passing through the forests of the Eastern Serengeti. In years of prolonged drought, the migration routes can change considerably.
In years when there has been no rainfalls, the wildebeests moved to the West and stayed in the Western Corridor instead of heading South. 

Where is possible to spot the herds of Great Migration in November

Lobo: despite the uncertainty of rainfalls and hence the time at which the Great Migration sets off, in Lobo there are still numerous herds in November.
This area is a good starting point from where to move according to the position of the Great Migration.
Central Serengeti: if the rainfalls are sufficient to revive the South pastures, the Great Migration can be spotted here or, at least part of it; the rest will reach the South-Eastern Serengeti.