Three domes of high pressure will dominate the U.S. weather map over the next few days. The first, over the Great Basin, will keep the Interior West clear, cold and dry but will likely produce strong Santa Ana winds in Southern California. The second dome, now centered over the mid Atlantic States is helping to produce heavy rains along the Gulf Coast; as the high drifts to the northeast, this rain will follow, bringing much needed precipitation to Alabama, Georgia and the Carolinas. Unfortunately, cold air, injected southward by the high pressure, will likely produce significant icing in north Georgia and western North Carolina.
The third and final high pressure dome, now lurking in western Canada, will drop into the Northern Plains and Upper Midwest, bringing frigid, Arctic air and producing lake-effect snows.
The movement and interaction of these domes is governed by the jet stream, which curves between them like an engine belt between rotors; dips in the jet allow domes to drop from the north while "ridges" (northward curves in the jet) permit high pressure to build from the south. In concert, pulses of low pressure (i.e. storms) ride along the domal boundaries, producing lift and, where moisture is sufficient, rain or snow.
