GMAT Sentence Correction (SC) | Re: QOTD: Hurricanes at first begin traveling from east to west

Hurricanes at first begin travelling from east to west, because that direction is the way the prevailing winds in the tropics blow, but they then veer off toward higher latitudes, in many cases changing direction toward the east before dissipating over the colder, more northerly waters or over land.

1) The placement of ' at first' will make more sense in the beginning of the sentence as it will show the flow of the sentence. i.e. at first.......and then something.......
2) The tense after 'but'
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