US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 325 PM EDT Tue Apr 06 2021 Valid Friday April 09 2021 - Tuesday April 13 2021 Hazards: - Heavy rain across portions of the Lower Mississippi Valley, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Southern Plains, Fri-Sat, Apr 9-Apr 10. - Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Fri-Sat, Apr 9-Apr 10. - Flooding occurring or imminent across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and the Ohio Valley. - Flooding likely across portions of the Lower Mississippi Valley. - Much above normal temperatures across portions of the Southern Plains, Fri, Apr 9. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Apr 12-Apr 13. - Much below normal temperatures across portions of mainland Alaska, Fri-Sun, Apr 9-Apr 11. Detailed Summary: During the upcoming medium range period (Friday, April 9 through Tuesday, April 13), the weather across the lower 48 will be predominantly influenced by a series of Pacific systems advancing across the northwestern states and swinging through a broad upper trough over the central United States. Starting with the central and western U.S. on Friday, a fast-moving upper level system and associated surface front will dive southeastward through the northern and central High Plains. Gusty winds are possible along and behind the frontal boundary, but current thoughts are that the wind gusts will remain slightly below warning criteria. Over the weekend, it looks like a repeat occurrence of high winds is possible over the northern Rockies/High Plains as another cold front quickly crosses the region. This system will also be responsible for high elevation heavy snow across the northern Cascades between late Friday and much of the day on Saturday. By early next week the frontal system will reach the southern High Plains and Southwest, accompanied by potentially windy conditions. No high wind areas were added to the hazards graphic today for the aforementioned regions given the uncertainty in magnitude, but changes are possible over the next couple of forecast cycles. Meanwhile, much above average temperatures are forecast to continue through Friday across southern Texas. High temperatures 10-20 degrees above average will equate to highs locally reaching 100-105F. Above average temperatures are also expected across the Desert Southwest for much of the period, but with highs maxing out in the mid-90s for the warmest locations. Farther east and downstream of the central U.S. trough, southerly flow will allow deep Gulf of Mexico moisture to stream northward into the Lower Mississippi Valley, Southeast, and sections of the Mid-Atlantic region between Friday and Sunday. This moisture will interact with a mid-upper level system transitioning out of the southern tier states, resulting in a broad area of moderate to heavy rainfall. The general consensus among our forecast guidance suggests that the heaviest precipitation will occur in the Friday to Saturday time frame. During the second half of the day on Friday, heavy rain and thunderstorms are likely to be mostly confined to around and just north of the central Gulf Coast (specifically between northern Louisiana and central Georgia). Then as this system slides northeastward around the central U.S. trough, the heavier rainfall may tend to shift into the southern/central Appalachians region Saturday, with heavy showers lingering across the central Gulf Coast States as well. There is still a lot of uncertainty with the exact placement of the heaviest precipitation, especially late on Saturday. Given the above normal recent rainfall across the Deep South and southern Appalachians, itâ€s worth keeping an eye on as the week progresses. Moderate to heavy rain is also possible farther north on Saturday and Sunday and the system lifts and stalls across the Great Lakes. However, widespread rainfall amounts appear to remain below one inch across the Midwest, Ohio Valley, Mid-Atlantic, and Northeast, thus no heavy rain areas were added to the hazards graphic. Locally heavy rain is possible, but given the recent stretch of warm and dry weather between the Great Lakes and Northeast, impacts should remain minimal. Temperatures across the eastern U.S. during this period are forecast to remain near or above average, with the warmest anomalies (10-20 degrees above average) located between the Lower Great Lakes and northern New England. By early next week yet another fast-moving system is expected produce showers and thunderstorms across the south-central U.S. and Deep South, but no hazards are expected during this period at the moment. Over Alaska, winter is maintaining a firm grip, as Arctic air entrenched over much of the mainland keeps temperatures much below normal through the end of the week and into the weekend. Temperatures will range from 20-30 degrees below normal, with a potential to set a few new records for early April. There will be some overall moderation to the temperatures beginning on Saturday across southwest portions of the state before temperatures rise closer to average by Monday across a majority of the state. Along with the relatively warmer temperatures, heavy precipitation is expected to make a return across northern sections of the Alaska Panhandle and the south-central region. This will be thanks to strong low pressure system located near the Aleutian Islands that is expected to funnel moisture northward from the North Pacific. Heavy snow will be possible across high elevations, with rain along the coast. Snell