US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 308 PM EST Tue Jan 14 2020 Valid Friday January 17 2020 - Tuesday January 21 2020 Hazards: - Heavy precipitation across portions of the Plains, the Mississippi Valley, the Southern/Central Appalachians, the Tennessee Valley, the Great Lakes, the Mid-Atlantic, the Northeast, the Southeast, and the Ohio Valley, Fri-Sun, Jan 17-Jan 19. - Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, and the Southern Plains, Fri, Jan 17. - Heavy snow across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Fri-Sat, Jan 17-Jan 18. - Heavy snow across portions of the Great Lakes, the Mid-Atlantic, the Northeast, and the Central Appalachians, Sat-Sun, Jan 18-Jan 19. - Flooding possible across portions of the Southeast, the Middle Mississippi Valley, the Great Lakes, the Ohio Valley, and the Upper Mississippi Valley. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding likely across portions of the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley. - Much below normal temperatures across portions of the Northern Plains and the Northern Rockies, Fri-Sat, Jan 17-Jan 18. - Much below normal temperatures across portions of the Central Plains, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains, Sun-Tue, Jan 19-Jan 21. - High significant wave heights for coastal portions of California and the Pacific Northwest, Sat-Sun, Jan 18-Jan 19. - Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, Fri-Sun, Jan 17-Jan 19. - Much below normal temperatures across portions of the Alaska Panhandle, Fri-Sat, Jan 17-Jan 18. Detailed Summary: The main threat in the medium range period will be a low pressure system moving across the central into northeastern U.S. through the weekend. With this system, rain is likely along the southern tier, with heavy snow possible along the northern tier from the Upper Mississippi Valley across the Great Lakes and into the interior Northeast Friday through Sunday. In the transition zone between snow and rain, a myriad of precipitation types are expected--snow, sleet, freezing rain, and rain are all possible, with many areas changing between multiple precipitation types--across the Middle Mississippi Valley eastward into the Ohio Valley and Appalachians on Friday into Saturday, with the Mid-Atlantic and coastal areas of the Northeast being impacted Saturday into Sunday. Travel will likely be impacted with this system. Behind the low pressure system, a strong, cold high pressure system will dive southward from central Canada into the Northern Plains/Midwest early next week. This is forecast to usher in bitterly cold air to those regions. The Northern High Plains should see below average low temperatures late this week, with high temperatures more than 20 degrees below average. As the high moves southward, the much below normal temperatures will impact the Upper/Middle Mississippi Valley early next week, with somewhat cooler weather moving into much of the eastern half of the U.S. as well. A front approaching the Pacific Northwest on Friday into Saturday could cause waves to swell to significant heights; the timing currently looks like Friday night into Saturday morning for these significant waves. High winds are possible offshore as well, but the strongest winds should not make it over land. Precipitation is likely in the Pacific Northwest, but does not look particularly heavy for this time of the year. Over Alaska, below normal temperatures are expected for the Panhandle with an upper low over the region through the end of the week. The upper low should pivot northwest by Sunday, leading to one more cold day across portions of the mainland. Precipitation is likely to affect the Panhandle and then along the Gulf of Alaska coast early next week, but uncertainty remains regarding if the amounts will be high enough to warrant drawing a hazard area. Tate