US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 220 PM EST Thu Feb 28 2019 Valid Sunday March 03 2019 - Thursday March 07 2019 Hazards: - Heavy snow across portions of the Central Great Basin, the Northern Plains, the Northern Rockies, the Central Rockies, California, the Northern Great Basin, the Pacific Northwest, and the Southwest, Wed-Thu, Mar 6-Mar 7. - Heavy snow across portions of the Central Rockies, the Northeast, the Central Great Basin, the Southern Rockies, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Central Appalachians, the Great Lakes, the Ohio Valley, and the Southwest, Sun-Mon, Mar 3-Mar 4. - Heavy snow across portions of the Central Rockies, Thu, Mar 7. - Severe weather across portions of the Southeast, the Lower Mississippi Valley, the Southern Appalachians, and the Tennessee Valley, Sun, Mar 3. - Flooding possible across portions of the Mid-Atlantic. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Mid-Atlantic, California, the Upper Mississippi Valley, the Southeast, the Pacific Northwest, and the Ohio Valley. - Flooding likely across portions of the Southeast. - Much below normal temperatures for much of the eastern two-thirds of the country, including the interior sections of the Pacific Northwest, Sun-Thu, Mar 3-Mar 7. - High winds across portions of mainland Alaska and the Aleutians, Mon-Tue, Mar 4-Mar 5. - High winds across portions of the Aleutians, Sun-Mon, Mar 3-Mar 4. and Wed-Thu, Mar 6-Mar 7. - High significant wave heights for coastal portions of mainland Alaska, Mon-Tue, Mar 4-Mar 5. Detailed Summary: Arctic air is expected to dominate much of the eastern two-thirds of the country, including the interior sections of the Pacific Northwest, through the medium range period as a cold high pressure system remains anchored across the region through the middle of next week. The actual temperatures could be more than 40 degrees below normal over the northern and central High Plains, which would equate to high temperatures between -10 F and 10 F. Models are coming into better agreement that a clipper type upper-level system will combine with an intensifying low pressure system off the northern Mid-Atlantic coast this weekend and bring a quick round of snow and some mixed precipitation across New England Saturday night into early Sunday. In the meantime, moisture from a Pacific cyclone should be moving across the southwestern U.S. into the southern Rockies Saturday night, and should begin to interact with the arctic front extending across the southern Plains by Sunday morning. Snow could be heavy at times over Colorado where the upslope flow will likely enhance the snowfall rate. By Sunday, a low pressure system is forecast to form over the southern Plains along the arctic front. The track and intensity of this low pressure system, as well as the degree of interaction with the arctic air mass are key elements for determining the wintry precipitation potential for the eastern U.S. later in the weekend and into Monday. Models showed a definite northward trend on the forecast low track yesterday but they appeared to have settled toward a track across the Mid-Atlantic States Sunday night, passing just off Cape Cod Monday morning. This will favor the best chance of snow across the Ohio Valley into Pennsylvania through Sunday night, with rain farther south across central to southern Appalachians as well as much of the Mid-Atlantic States. The snow should most likely spread into southern New England early Sunday followed by coastal Maine during the day. This is reflected on the latest WPC hazards chart with an area of heavy snow extending from the Ohio Valley through southern New England. Farther to the south, potential exists for heavy rain and thunderstorms reaching severe levels across the Deep South on Sunday ahead of the low pressure system. A strong cold front should then push the heavy rain into the Southeast Sunday night while ushering in colder air and ending the heavy rain for the Deep South. Behind the snow over parts of the eastern U.S., arctic air will once again dominate much of the eastern two-thirds of the country with well below normal temperatures spreading down into Florida. Meanwhile, moisture from the next Pacific cyclone is forecast to reach California on Tuesday (3/5), bringing the next round of heavy rain for the lower elevations with heavy snow once again for the Sierra Nevada. The rain should move into the Intermountain West on Wednesday (3/6) as mixed precipitation reaches the northern and central Rockies. By Thursday, some wintry precipitation should be moving out into the central Plains and further into the Midwest. Unsettled weather will likely linger across much of the northwestern U.S. down into central California. For western Alaska and the Aleutians, high winds will be likely through the weekend, spreading into western Alaska on Monday into Tuesday thanks to a strong low pressure system moving into the Bering Sea. Significant waves can also be expected early next week near the coast of western Alaska as the next Pacific cyclone brings the next round of high winds into the western Aleutians by next Wednesday. Kong