Final answer:
A negative phase of the Arctic Oscillation typically leads to colder and snowier conditions in Europe and the eastern United States, characteristic of Continental Climates or Type D climates in these regions.
Step-by-step explanation:
The blank in the question should be filled with negative to correctly complete the sentence: A negative phase of the Arctic Oscillation (AO) is typically associated with cold and snow conditions in Europe and the eastern U.S. During the negative phase of the AO, the polar vortex is weakened, allowing cold air to flow southwards, bringing colder temperatures and snow to these regions.
Type D or Continental Climates, which can be found in the Great Lakes region of the United States and much of Canada, also experience similar conditions with cool to hot summers and cold winters with snow. These climate regions are away from the moderating influence of large bodies of water and further north, which contributes to the colder winter weather.