31. The result is the polar air forms a coherent rotating air mass : the polar vortex. 32. The leading edge of a new polar air mass will stretch from upper Michigan to Montana. 33. The strongest winds are in the mid-latitudes where cold polar air meets warm air from the tropics. 34. High pressure in the central Plains will be associated with a mixture of Pacific and polar air . 35. Polar air will flow back into the Northeast on Saturday as low pressure strengthens near Nova Scotia.36. A push of polar air into the Plains will produce scattered snow showers in the Missouri Valley. 37. A fresh surge of polar air will sweep across the Northeast on brisk winds from the Northwest. 38. In winter, due to the action of masses of polar air the temperature can reach 6 �C. 39. Snow showers will dust the western Great Lakes as polar air returns to the region on gusty winds. 40. A : Conditions that spawn tropical storms and hurricanes involve sea and air temperatures and polar air flows.
