March - May 2003

Latest Seasonal Assessment - A large storm system produced several inches of precipitation across portions of southern California and Arizona during the second week of February. Further north, unsettled weather across parts of Washington, Oregon, Idaho, Wyoming and Montana helped to increase mountain snow pack but was not enough to result in significant drought improvement. Unfortunately, large moisture deficits are still prevalent across much of the West. Wetter than normal conditions are expected during the next three months or so across southern California, southern Nevada, Arizona, New Mexico, Colorado and Utah. This should result in an improvement of pasture conditions, an increase in soil moisture and benefit to local agriculture. However, due to the large moisture deficits accumulated during past years, the improvement of streamflow and water supplies will be minimal. As a result, water shortages are expected to continue throughout the period. Further north across most of Montana and Wyoming, below normal precipitation will result in the continuation of drought conditions. Further east, drought conditions are expected to continue across western South Dakota and much of North Dakota. Drier than normal conditions are anticipated across the Great Lakes region. As a result, drought conditions are expected to persist through May.

Across the western U.S., a large Pacific storm system dropped several inches of precipitation across portions of southern California and Arizona during the second full week of February. This helped to ease dryness and resulted in the reduction of one Drought Monitor category across portions of southern California. Across Washington, Oregon, Idaho and Montana, unsettled weather during the end of January and the first week of February helped to increase mountain snow pack. Unfortunately, this was not enough to result in a significant improvement of drought conditions. Large moisture deficits exist across much of the West due to accumulated negative precipitation anomalies during recent years. Widespread D3 - D4 drought conditions are prevalent. Above normal precipitation is expected across much of the southwestern U.S. due to the El Niño conditions still prevalent in the Pacific. This should result in some increase in top soil moisture, improvement of pasture conditions and benefit to local agriculture. However, the anticipated wetter-than-normal period will not make up the large, long term moisture deficits that exist. As a result, the improvement of streamflow, groundwater and reservoir storage will be minimal. This is evident in the USDA/NRCS summer streamflow forecasts produced February 1. As a result, water shortages are expected to continue through the period. Across most of Montana and Wyoming, precipitation is expected to be below normal, therefore the drought will likely persist with little, if any, improvement.

Across much of the Great Lakes region and adjacent parts of Iowa, Illinois and Indiana, drier than normal conditions during the fall and winter have resulted in D1 - D2 drought conditions. Drier than normal conditions are anticipated through May. As a result, drought conditions will persist across these areas. The drought may expand southward into central Illinois, central Indiana, northern portions of Ohio and adjacent portions of northwestern Pennsylvania. Drought may also expand into Wisconsin, Minnesota and eastern North Dakota as conditions have been drier than normal this winter. Across northwestern Missouri, where conditions have been very dry, near normal precipitation is expected. This will result in an increase in top soil moisture and short term moisture supplies. However, a prolonged period of above normal precipitation will be required to ease longer term moisture concerns, such as groundwater.