Contact:  Randee Exler             FOR IMMEDIATE RELEASE
                                   3/20/96

WINTER SNOW MELT REDUCES SPRING FLOODING POTENTIAL

With most winter snow already melted in many parts of the country, serious flooding is unlikely for most of the United States this spring. The current outlook could change, however, if there is substantial rainfall over the next month, according to officials at the National Oceanic and Atmospheric Administration.

"The areas of highest risk for spring flooding include portions of the Southeast, the upper peninsula of Michigan, northern Wisconsin and Minnesota, and the drainages in eastern North Dakota. In the West, concern focuses on an area along the Montana-Idaho state line extending into northwestern Wyoming, and including most of Idaho, northern and western Nevada, the Sacramento and San Joaquin River drainages in California, and the Okanagan region in north central Washington. However, extreme flooding would only occur if these regions experienced significant rainfall," said Frank Richards, director of NOAA's National Hydrologic Information Center at the National Weather Service.

Many areas in the country that have the highest concern for spring flooding include those reporting above-average snow packs that have not already melted. The broadest extent of snow for the country is found in the higher elevations in the West. Many above- average snow packs are found in north-central Colorado and northwestern Wyoming. Above-average snow amounts cover locations in much of the higher elevations in Colorado, western Wyoming, southwestern Montana, eastern and central Idaho, northeastern Utah, northeastern Nevada, and the Sierra Nevada along the California- Nevada state line. Considerable snow is also found in areas around the northern Great Lakes; this pocket of deep snow extends westward through northern Minnesota.

In Alaska, the potential for spring breakup flooding from snow melt and ice jams is moderate to high for the Yukon, Kuskokwim, Koyukuk and Kobuk Rivers, and moderate for the Copper and Tanana Rivers. The potential for localized small stream and urban flooding in the south-central section of Alaska is high.

On the West Coast, October and November were quite wet in Oregon and especially in Washington. This wet period culminated at the end of November in severe flooding along the coastal portions of the Pacific Northwest. While flooding decreased by mid-December, conditions remained wet. In early February, a surge of warm, moist air brought another round of widespread severe flooding in the western portions of Washington and Oregon, with a number of locations reporting record high river levels.

The risk of spring flooding on the eastern seaboard is lower than normal because snow from January's blizzard largely melted off. The Blizzard of '96 concluded a prolonged period of heavy snow and very cold conditions in the Northeast. However, less than two weeks after the storm had paralyzed much of the eastern seaboard, substantial portions of the deep snow cover were gone. Warm and extremely humid air streamed north out of the Gulf of Mexico ahead of a major rainstorm. This devoured the snow pack, melting it at rates that were almost unprecedented. This snow melt, combined with heavy rainfall, produced regional widespread major flooding.

With the exception of parts of the Southeast, most of the rest of the nation, from the Rockies eastward to the Atlantic coast experienced a lack of precipitation in February and early March, significantly minimizing flooding potential. Southeastern California, southern Nevada, southern Utah, Arizona, New Mexico, Colorado, Kansas, Oklahoma and most of Texas as well as portions of Nebraska, Iowa, Illinois, Missouri, Arkansas and Louisiana have been extremely dry since the start of the Water Year on Oct. 1, 1995.

Temperatures exhibited wide excursions over the winter. On more than one occasion, temperatures varied by 50-60 degrees over no more than several hundred miles. These conditions were typically associated with Arctic air sweeping away record warmth ahead of it, occasionally resulting in temperature swings of more than 100 degrees at some locations in less than a week. Episodes of record warmth eliminated the snow cover in many areas, which explains how the dearth of snow now observed could occur in a year that saw record snowfall in many areas. The warmth also greatly reduced river ice in many locations, limiting the risk of ice jam flooding to only some of the northernmost rivers.

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