Contact: Randee Exler FOR IMMEDIATE RELEASE
(301) 713-0622 3/13/95
The West Coast, parts of the Southeast and the upper Midwest are primary areas of concern for spring flooding, according to the 1995 National Hydrologic Outlook issued today by the National Oceanic and Atmospheric Administration. Conditions in the rest of the country make flooding less likely than normal at this time. Water supplies should be adequate throughout the nation, except for limited areas in Montana, Idaho, Colorado and Wyoming where problems may arise later in the summer.
Over the past week, California saw the renewal of flooding that, in some places, rivaled the January floods. A series of powerful storm systems slammed into California last week, bringing strong winds and torrential rains. As in January, the Russian, Napa and Sacramento Rivers spilled out of their banks. There was also serious flooding in the Monterey area, on the Pajaro, Carmel and Salinas Rivers. This storm came at a time when soils were already wet and many streams were still running high, causing rivers to rise more rapidly than in January. Flash flooding wreaked havoc in Monterey and San Luis Obispo Counties, driving thousands of people out of their homes.
Snowfall in the Sierras has been equally impressive, with as much as six feet of new snow in the higher Sierras. This will further improve California's water supply situation. After a long period of abnormally dry winters, adequate water supplies for the coming year are assured.
This past winter has been characterized by flooding episodes along the West Coast and in much of the Southeast. At the same time, much warmer than normal temperatures have been recorded in most of the nation. This has resulted in much less snow than normal in the Midwest, where spring snowmelt flooding is almost an annual event. There is also minimal snow in the Northeast as a result of the warm winter. In the West, where winter snow is critical to water supplies for many locations, the warm, wet winter has confined heaviest snows to the higher elevations. Much of the winter precipitation at the lower levels has fallen as rain. Oregon, the northern panhandle of Idaho, most mountainous areas in Montana, and eastern Wyoming have fallen short of normal snow amounts so far this year.
In addition to California, streams are running above average in Washington and Oregon, most of Arizona, the upper Midwest, including the Dakotas, Minnesota and Wisconsin, in much of the Ohio and lower Mississippi River basins, and in the Southeast where chronic flooding has occurred throughout the winter. In general, soils are wet in the locations with high streamflow and in some adjacent areas.
Given current conditions, significant snowmelt flooding is unlikely this year, with the possible exception of limited portions of North Dakota and Minnesota. Similarly, the warm winter has greatly reduced the potential for ice jam flooding this year. However, there is still time left to develop a sufficient snow cover in the upper Midwest and Northeast to cause concern for snowmelt flooding.
Pre-existing wet conditions in California, Washington and Oregon, a significant part of Nevada and most of Arizona, the Ohio River basin, as well as in the Southeast, from eastern Texas to the Atlantic, makes these areas vulnerable to flooding, given rainfalls that would not be abnormal for this time of year.
Although widespread water supply shortages are unlikely this year, reservoir levels in parts of Nevada, Idaho, Montana, Colorado and Wyoming are considerably below normal. Snowmelt into the summer will probably be adequate to support water needs of these areas. However, those locations that did not have reservoirs to store runoff as a result of rain and snowmelt from lower elevations during this warm winter, may see some problems because melt of only high-elevation snow may prove insufficient to sustain adequate streamflow levels throughout the summer.