After enduring a prolonged, severe drought, central Texas is under a flood watch as heavy rains have swept across the region for the past two days and are likely to continue for at least the next 24 hours. A stationary front bisects the country, from north to south, as the jet stream has taken a broad dip across the western U.S.; meanwhile, the eastern half of the country basks in summer-like weather under a ridge of high pressure.
This high pressure, centered over the northeast, is sweeping moisture from the Atlantic and Gulf of Mexico up against the cold front and areas just east of the front, from Texas to Nebraska, are receiving the copious cargo. While rain is welcome in the drought areas, this heavy precipitation is unfortunately arriving during the fall harvest, a time when dry weather is vital. In addition, the heavy rain is falling at a rate that cannot be absorbed by the hard, sun-baked earth, producing rapid run-off and subsequent flooding along stream channels.
Both the drought and the deluge have been produced by stationary weather patterns and it is not unusual that extreme weather events occur in sequence, one setting the stage for the other. Seasonal norms are merely averages based on long-term observations; a fickle jet stream or a stagnant zone of high pressure can, and often do, defy our expectations.
