US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 232 PM EST Fri Feb 01 2019 Valid Monday February 04 2019 - Friday February 08 2019 Hazards: Heavy rain from portions of the Middle/Lower Mississippi Valley to the Ohio Valley, Wed-Thu, Feb 6-Feb 7. Heavy snow across portions of the California, the northern Rockies, the Upper Midwest, and the Upper Great Lakes, Mon, Feb 4. Flooding possible across portions of the Middle Mississippi Valley. Flooding occurring or imminent across portions of the Southeast and the Great Lakes. High winds across portions of the Northern/Central Plains, the Upper Mississippi Valley, and the Upper Great Lakes, Mon, Feb 4. Much below normal temperatures across portions of the Northern Great Basin, Northern Rockies, Northern/Central Plains, and the Upper Mississippi Valley, Mon-Fri, Feb 4-Feb 8. High winds across portions of mainland Alaska and the Aleutians, Mon-Tue, Feb 4-Feb 5. High significant wave heights for coastal portions of mainland Alaska and the Aleutians, Mon-Tue, Feb 4-Feb 5. Detailed Summary: The hazards period (Monday 2/4 - Friday 2/8) begins with a cyclone moving through the Upper Midwest into the Upper Great Lakes. Heavy snowfall will be possible to the north of this low from northern Minnesota to the Upper Peninsula of Michigan. The snowfall combined with gusty winds across the same area, may result in blizzard conditions at times. Meanwhile, out west, a deep upper-level low entering California which will allow for continued widespread rain and mountain snows across California and much of the Western states. The best chance for heavy/significant snowfall looks to be across the Sierra mountains of California, as well as parts of the northern Rockies. As this system emerges into the Plains, a surface low is likely to develop in the Central High Plains next Wednesday. Models continue to show uncertainty regarding the track and intensity of this surface low, but there is a decent signal for likely widespread rainfall along the cold front from the lower/middle Mississippi Valley to the Ohio Valley next Wednesday and Thursday. Rainfall may also linger into next Friday as well, depending on how quickly the system departs. Regarding temperatures across the country, a significant warming trend is expected for the eastern half of the country through at least the middle of next week as an upper-level ridge propagates eastward. Temperatures for some locations, especially across the Ohio Valley, could be 10 to 20 degrees above normal. To the north, the next surge of arctic air should move into the northern states by the end of this weekend, spreading south and eastward through the week into the central Plains and the Upper Midwest. Next Thursday and Friday, there is some disagreement in the models on how far south the cold air propagates (this is dependent on the evolution of the central U.S. cyclone mentioned above), but at this time, the best chance for much below normal temperatures (-12+ degrees) is across the Northern Rockies/High Plains, into the Northern and parts of the Central Plains, and the Upper Mississippi Valley. In Alaska, a couple of cyclones cross the Aleutians and into the Bering Sea next week. This is likely to result in periods of high winds and significant waves, most likely along the Aleutians/western Peninsula, and up the mainland Alaska west coast. The best chance for these hazards would be next Tuesday, 2/5. The next cyclone during the middle of the week next week is likely to have gusty winds associated with them, but confidence is not high at this point on whether that reaches criteria for the medium range hazards chart. Santorelli