US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 311 PM EST Wed Dec 19 2018 Valid Saturday December 22 2018 - Wednesday December 26 2018 Hazards: Heavy rain across portions of California and the Pacific Northwest, Sun-Mon, Dec 23-Dec 24. Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains, Wed, Dec 26. Heavy snow across portions of California, the Central Great Basin, the Pacific Northwest, the Northern Rockies, and the Northern Great Basin, Sun-Mon, Dec 23-Dec 24. Heavy snow across portions of the Central Plains, the Upper Mississippi Valley, and the Northern Plains, Wed, Dec 26. Flooding possible across portions of the Southern Appalachians, the Mid-Atlantic, the Northeast, and the Central Appalachians. Flooding occurring or imminent across portions of the Southeast, the Mid-Atlantic, and the Southern Plains. Flooding likely across portions of the Southeast. High winds across portions of mainland Alaska and the Aleutians, Mon, Dec 24. High significant wave heights for coastal portions of mainland Alaska and the Aleutians, Mon-Tue, Dec 24-Dec 25. Detailed Summary: A series of systems look to move into the Pacific Northwest with ample onshore moisture allowing for heavy rainfall along the coast from Washington state to northern California with significant snow accumulations in the higher terrain of the Cascades down into parts of the Sierra Nevada mountains. While there is a chance for rain each day, the most significant impacts are expected Sunday-Monday, December 23-24. Heavy accumulating snows may also spill over into parts of the northern Rockies as well. Given the timing over the Holiday weekend, both road and air travel delays are expected. Elongated upper level troughing over the Western U.S. early next week will push into the Central states by Wednesday. A low is expected to spin up at the surface with heavy rainfall possible along and ahead of the trailing cold front across parts of eastern Texas/Oklahoma into the Middle/Lower Mississippi Valley. To the north of the low, an area of heavy snowfall is possible, most likely from parts of the Central Plains into the Upper Midwest. Uncertainty is still high on exact placement of the heaviest axis and the amounts, but models show enough consensus to warrant a heavy snow area on the hazards chart for next Wednesday, December 26. In Alaska, a couple of deep surface cyclones are forecast to move over or south of the Aleutians towards the Gulf. This may result in significant waves (>20 ft) or high winds (>50 knots) across portions of the Aleutians into the western part of the Panhandle Sunday-Monday. Santorelli