In North America, storm systems generally move from west to east. Since showers and thunderstorms are produced along the trailing cold front and draw on atmospheric moisture ahead of the front, they are usually transient and of little consequence. It is only when the front flattens out and becomes stationary that storms "train" along the front, repeatedly passing over the same areas and producing floods.
Over the past 48 hours, the heavy rains and extensive flooding along the East Coast have resulted from a different and unusual weather pattern. A tropical depression, characterized by copious, deep moisture, was funnelled northward between two domes of high pressure, one covering the east-central portion of the U.S. and the other over the Atlantic Ocean. Forced out of the Gulf of Mexico by the advancing edge of the western dome and directed northward by the western edge of the Atlantic dome, this tropical moisture was dumped along a narrow swath, from Miami to New York. While it provided welcome relief for drought-plagued areas of the mid-Atlantic, areas to the south and north have experienced severe flooding.
As of this morning, most of the rain has moved into New England and will soon drift eastward above the Atlantic dome. Meanwhile, here in Missouri, we have enjoyed sunny, cool and dry conditions, safely entrenched beneath the continental dome of high pressure.
