The oscillation exhibits a "negative phase" with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a "positive phase" in which the pattern is reversed. In the positive phase, higher pressure at midlatitudes drives ocean storms farther north, and changes in the circulation pattern bring wetter weather to Alaska, Scotland and Scandinavia, as well as drier conditions to the western United States and the Mediterranean. In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the negative

phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general "opposite" to those of the positive phase, as illustrated below.

Over most of the past century, the Arctic Oscillation alternated between its positive and negative phases. Starting in the 1970s, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia.

On September 6 of last year, I first observed what I think was a localized anticyclone. Storm was about 45km across, had particularly calm clear weather within the cyclone, while at the circumference of the storm, variations of extreme weather phenomena were taking place. 

The storm moved up from Umea Sweden, following the coast of the Gulf of Botnia, up to Haaparanda Sweden then down along the coast until it reached Oulu.  I cant verify whether or not it continued south along the coast beyond Oulu, because I am still not sure what I observed.

 The storm displayed, snow, hale, thunder and lightening, strong winds, and finally rain as it passed through. After passing, the storm left no evidence of it ever being here, with a normalization of conditions immediately afterwards.

 I could use any an all help on this matter as possible. 

In meteorology, an anticyclone (that is, opposite to a cyclone) is a weather phenomenon in which there is a descending movement of the air and a high pressure area over the part of the planet's surface affected by it. Anticyclonic flow spirals in a clockwise direction in the Northern Hemisphere and counter-clockwise in the Southern.