• The ``Pineapple Express,'' a series of warm, wet storms heading east from Hawaii, drenching Southern California and the far Southwest, which already are beset with heavy rain and snow. It could cause flooding, avalanches and mudslides.

• An ``Arctic Express,'' a mass of cold air chugging south from Alaska and Canada, bringing frigid air and potentially heavy snow and ice to the usually mild-wintered Pacific Northwest.

• A warm, moist storm system from the Gulf of Mexico drenching the already saturated Ohio, Tennessee and Mississippi valleys. Forecasters also expect heavy river flooding and springlike tornadoes.

All three are likely to meet somewhere in the nation's midsection and cause more problems, sparing only areas east of the Appalachian Mountains.

``You're talking a two- or three-times-a-century type of thing,'' said prediction center senior meteorologist James Wagner, who has been forecasting storms since 1965. ``It's a pattern that has a little bit of everything.'' Source.