US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 223 PM EST Fri Dec 20 2019 Valid Monday December 23 2019 - Friday December 27 2019 Hazards: - Heavy precipitation across portions of California, Thu, Dec 26. - Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains, Fri, Dec 27. - Heavy rain across portions of the Southeast and the Southern Mid-Atlantic, Mon-Tue, Dec 23-Dec 24. - Heavy snow across portions of California, the Central Great Basin, the Pacific Northwest, the Northern Great Basin, and the Southwest, Mon, Dec 23 and Thu-Fri, Dec 26-Dec 27. - Heavy snow across portions of the Southern Rockies, the Central Rockies, the Central Great Basin, and the Southwest, Tue-Wed, Dec 24-Dec 25. - Flooding possible across portions of the Southeast and the Northern Plains. - Flooding occurring or imminent across portions of the Pacific Northwest and the Northern Plains. - Flooding likely across portions of the Pacific Northwest and the Northern Great Basin. - High winds across portions of the Southeast, Mon-Tue, Dec 23-Dec 24. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon, Dec 23. - High winds across portions of the Aleutians, Mon, Dec 23. - High significant wave heights for coastal portions of mainland Alaska and the Aleutians, Mon, Dec 23. Detailed Summary: Low pressure over the Southeast, on Monday, will move eastward out over the Western Atlantic by Tuesday. The low will pull moisture off the Atlantic and stream into the Southeast on Monday. The moisture and the low will aid in producing an area of heavy rain over parts of the Southeast Coast into parts of the Southern Mid-Atlantic also on Monday into Tuesday. The pressure gradient associated with the low will be strong enough to produce high wind over parts of the Southeast Coast, likewise, on Monday into Tuesday. Meanwhile, a front extending from parts of the Northern Intermountain region southward to Southern California will move eastward to the Middle Mississippi Valley/Southern Plains by Wednesday, Christmas, a long with an upper-level trough that moves inland. Some moisture will come inland over Southern California from the Pacific and aid in producing an area of heavy snow over the Central Sierra Nevada Mountains on Monday. The energy associated with the southern parts of the upper-level energy will aid in producing areas of heavy snow over parts of the Mogollon Rim and the San Juan Mountains on Tuesday into Wednesday, Christmas Eve and Christmas day. An upper-level low will develop over the Pacific just off the California Coast on Wednesday evening into Thursday. The system will aid in pulling moisture off the Pacific developing an area of heavy rain over parts of Southern California on Thursday. Some of the moisture and onshore flow over parts of the Pacific Northwest will aid in producing heavy snow over parts of the Cascades into the Sierra Nevada Mountains on Thursday into Friday. The upper-level trough associated with the aforementioned upper-level low moves eastward over Northwestern Mexico by Friday. There is uncertainty associated with the system with some models moving the trough axis faster eastward than other models. There is enough of a signal in the models to display an area of heavy rain over parts of Southern Plains on Friday. Over Alaska, deep low pressure over the Aleutians will move into the Gulf of Alaska and weaken on Tuesday. The pressure gradient associated with the deep low will produce wind with speeds of 50 knots over parts of the Aleutians on Monday. An area of High Winds is depicted on the hazards chart on Monday. A long with the strong wind, and area of Significant Waves will also be placed on the hazards chart also on Monday. A plume of moisture will move off the Gulf of Alaska and stream moisture into the Alaska Panhandle on Monday. An area of heavy precipitation is depicted on the hazards chart over parts of the Alaska Panhandle into parts of Southeastern Mainland on Monday. Ziegenfelder