U.S. Seasonal Drought Outlook.

September 7, 2012 – U.S. Seasonal Drought Outlook: Drought continues to cover a large portion of the country in early September, but beneficial rains finally brought improvement to a significant part of this area.

Heavy, beneficial rains, primarily from the remnants of Hurricane Isaac, fell on much of the Mississippi and lower Ohio Valleys during the last 2 weeks. Parts of Arkansas, Missouri, eastern Kansas, and Illinois recorded over 5 inches of rain, and amounts reached as high as 10 inches in isolated locations. Elsewhere, moderate to heavy rains also fell on portions of the mid-Atlantic, and isolated sites in Arizona received 2 or more inches of rain.

The seasonal decline in temperatures over the next 3 months will substantially reduce surface water lost to evaporation and vegetative growth. Furthermore, precipitation tends to fall at a more moderate rate over a longer period of time, which recharges soil moisture efficiently. Snowfall similarly holds moisture that seeps slowly into the soil as it melts.

These factors, along with anticipated precipitation patterns at least partially driven by the developing El Nino episode, should bring some relief to drought-affected areas in the East, the Mississippi Valley, the Midwest, and the northern Great Plains. The odds also favor some degree of improvement across a large swath of the Southwest and across southern Texas.

Still, there remains a large area covering the central and southern Plains, the central and northern Rockies, the central Intermountain West, and much of California where drought conditions are expected to persist. Most of these areas are moving toward a climatologically drier time of year, and there is no compelling indication that substantially above-normal precipitation will fall during the next 3 months. (Credits: The National Weather Service and NOAA).

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