Articles by Roberto Rondanelli
May 1, 2007
Yesterday started off very cold and damp, however it quickly shifted to sunny weather and temperatures slightly above 70°F. If you are curious about the source of this springtime variability, at least part of it is due to the jet stream that is currently located over Boston. The jet acts as a guide for smaller scale perturbations that can potentially cause weather variations over a few hours. Also, since the jet stream in the upper atmosphere is concomitant with a large temperature gradient near the surface and lower atmosphere, to be close to the jet is also to be close to the boundary between the polar air masses and the tropical air masses. This is yet another source of variability since it provides the potential for rapid changes in temperature due to air crossing over either from the pole or from the equator side of the boundary.
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March 2, 2007
Once strong, the low pressure centered over the Midwest is now an old storm, slowly filling up and loosing power. During the peak of its activity though,the low produced a potpourri of bad weather — tornadoes, hailstorms, and snow from Missouri to Illinois. The cold front, part of the low, will continue making its way towards the Atlantic, affecting Florida and the southern part of the East Coast with thunderstorms.