US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 257 PM EDT Wed Apr 07 2021 Valid Saturday April 10 2021 - Wednesday April 14 2021 Hazards: - Heavy rain across portions of the Southeast, the Lower Mississippi Valley, and the Southern Plains, Tue-Wed, Apr 13-Apr 14. - Heavy rain across portions of the Southeast, the Mid-Atlantic, the Lower Mississippi Valley, the Southern Appalachians, and the Tennessee Valley, Sat, Apr 10. - Heavy rain across portions of the Southeast, Sat-Sun, Apr 10-Apr 11. - Severe weather across portions of the Southeast and the Tennessee Valley, Sat, Apr 10. - Flooding occurring or imminent across portions of the Lower Mississippi Valley. - Flooding likely across portions of the Lower Mississippi Valley. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Wed, Apr 12-Apr 14. - Much below normal temperatures across portions of mainland Alaska, Sat-Sun, Apr 10-Apr 11. Detailed Summary: During the upcoming medium range period (Saturday, April 10 through Wednesday, April 14), the weather across the lower 48 will be predominantly influenced by a series of Pacific systems advancing across the north-central states and reinforcing a broad upper trough over the Great Lakes. Starting with the eastern half of the country, much of the active and hazardous weather during this time frame will be across the Southeast and Lower Mississippi Valley. Southerly flow ahead of an approaching cold front will allow deep Gulf of Mexico moisture to stream northward into the central Gulf Coast States, Southeast, and sections of the southern Appalachians this weekend. This moisture will also interact with a mid-upper level system transitioning out of the southern tier states, resulting in a broad area of moderate to heavy rainfall. By Saturday, a low pressure center will be in the process of strengthening and sliding northeast out of the Ohio Valley and over the Great Lakes. Showers and thunderstorms are expected to race ahead of the cold front across the Southeast and central Gulf Coast, producing widespread rainfall amounts over an inch. Severe thunderstorms are also possible on Saturday across the Florida Panhandle, southeast Mississippi, and southwest Georgia according to the Storm Prediction Center. As the frontal boundary and thunderstorm complex shifts south on Sunday, heavy rain will remain possible across central and western Florida. Farther north, moderate to heavy rain is also possible 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 this weekend. By early next week, a separate system with a strong trailing cold front is forecast to reach the Gulf of Mexico and spark unsettled weather across the Lower Mississippi Valley and central Gulf Coast region once again. The greatest chances for heavy rain is currently located between far east Texas and southern Mississippi, including much of Louisiana as the frontal boundary stalls just to the south on Tuesday and Wednesday. Parts of this area have seen above normal rainfall over the last month, with more on the way this weekend, therefore any additional rain may exacerbate flooding concerns. Meanwhile throughout the central and western U.S., little to no precipitation hazards are expected through next Wednesday. Showers are possible beginning on Monday across the Southern/Central Plains and Central Rockies behind a cold front, but amounts at moment do not appear hazardous. There is growing concern that moderate snow may fall across the Central Rockies and central High Plains beginning next Wednesday, but uncertainty is still very high regarding precipitation amounts and precipitation type. Gusty winds may accompany the aforementioned cold front as it crosses the northern Rockies on Saturday, before reaching the Central Plains on Sunday and Southern Plains by Monday. Wind gusts may reach upwards of 50 mph and a hazard area may be added in future forecast cycles throughout the High Plains. Gusty winds are also a possibility across the Southwest on Wednesday as a low pressure system strengthens near the Four Corners region. Temperatures will start off the weekend above average across the Plains, with below average temperatures behind the front in the Northwest. By the beginning of next week, below average high temperatures will struggle to make it out of the 40s and 50s throughout the central United States. Low temperatures are forecast to dip below freezing across the Northern/Central Plains and Upper Midwest by Tuesday, where the recent warmth may have caused some early-season crops to begin blooming already. Over Alaska, winter is maintaining a firm grip, as Arctic air entrenched over much of the mainland keeps temperatures much below normal through this 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 region. Along with the relatively warmer temperatures, heavy precipitation is expected to make a return by Monday 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