61.   A surge of arctic air will reach the border states Tuesday night.

62.   A vigorous west-to-east jet stream flow will keep arctic air locked in northern Canada for the next several days.

63.   A surge of arctic air will push across the Great Lakes on Thursday behind a strong cold front.

64.   Additionally, a limited supply of arctic air over eastern Canada will cause precipitation to mix with and change to rain for locations near the coast.

65.   Alberta Clippers often follow on the heels of an outbreak of Arctic air and, though moisture is lacking, can produce several inches of dry, fluffy snow.

66.   But Alberta clippers attain great notoriety because they are a mechanism by which Arctic air is transported south.

67.   But in winter, potent weather systems draw Arctic air south, while currents of warm air stream north.

68.   But low-level Arctic air will hold its ground, setting the stage for broken areas of snow and pockets of freezing rain.

69.   But the main invasion of Arctic air will wait until the caboose in a train of Pacific disturbances passes by the region early next week.

70.   By late this week, the current supply of Arctic air over the United States will be depleted.