US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 259 PM EST Tue Feb 02 2021 Valid Friday February 05 2021 - Tuesday February 09 2021 Hazards: - Heavy precipitation across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, the Southern Plains, the Ohio Valley, and the Tennessee Valley, Tue, Feb 9. - Heavy snow across portions of the Great Lakes and the Upper Mississippi Valley, Fri, Feb 5. - Heavy snow across portions of the Northeast and the Great Lakes, Fri-Sat, Feb 5-Feb 6 and Mon, Feb 8. - Heavy snow across portions of the Mid-Atlantic, the Northeast, and the Great Lakes, Mon, Feb 8. - Much below normal temperatures across portions of the Central Plains, the Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, Sun-Tue, Feb 7-Feb 9. - Much below normal temperatures across portions of the Central Plains, the Northern Plains, the Northern Rockies, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Great Lakes, Sat-Tue, Feb 6-Feb 9. - Much below normal temperatures across portions of the Great Lakes, the Mid-Atlantic, the Northeast, and the Central Appalachians, Mon-Tue, Feb 8-Feb 9. - Much below normal temperatures across portions of mainland Alaska, Mon-Tue, Feb 8-Feb 9. Detailed Summary: The medium range period (Friday, February 5th to Tuesday, February 9th) will feature a few strong cold fronts traversing the central and eastern United States. The leading cold front on Friday across the East will be associated with a strengthening low pressure system near the Great Lakes. As a result, heavy snow will likely be continuing across the Upper Great Lakes on Friday. Lake-enhanced and lake-effect snow will also be likely as strong west-northwest winds rush in behind the system. Lake-effect snow could continue into the weekend across the typical snowbelts downwind of Lake Ontario as well. As the low pressure system enters southern Canada, moderate snowfall is possible across northern New England Friday night into Saturday. Further south, rain showers and isolated thunderstorms will accompany the system across the Southeast on Friday. The next potential system to bring impactful wintry precipitation has a lot more uncertainty associated with it. Current forecast guidance shows two impulses of upper-level energy rounding the base of a deep upper-level trough and potentially leading to a strong surface cyclone riding up the East Coast from the Mid-Atlantic to New England between Sunday and Monday. This scenario would lead to widespread heavy snow for much of the major cities from Virginia to Maine. However, there is the potential that the timing of these two pieces of energy don't align, and only a weak surface wave brings light snowfall. Using the latest Winter Weather Outlook, probabilities remain highest across the Northeast and New England for impactful snowfall. A heavy snow area was added to this region in today's day 3-7 hazards graphic given the increasingly snowy trend in ensemble guidance. Be sure to check back as subtle changes to this forecast are likely. The most widespread hazard during this time frame will be associated with a bitterly cold airmass entering the north-central U.S. behind a secondary cold front. For much of the country from the northern Plains to Ohio Valley, the coldest temperatures of the season will be likely and a few daily records could be in jeopardy. Subzero degree temperatures are forecast to enter the northern Plains behind the front on Friday and spill into the central Plains by Saturday. Low temperatures around 10 to 20 degrees below average will then enter the Ohio Valley by Sunday and Monday. Cold air will also be found as far south and east as the Southern Plains, lower Mississippi Valley, and Mid-Atlantic by Monday. Places such as Chicago and Minneapolis will likely experience multiple days with low temperatures below zero beginning on Saturday. Wind chill values will be even colder and likely in the minus 20 degree range. Confidence is highest across the Upper Midwest and northern Plains regarding the extreme cold, with timing differences and less confidence on the strength of the cold air mass towards the south and east. By Tuesday, precipitation is expected to break out across the Arklatex region along an inverted trough. Given the cold airmass in place there is the potential for impactful freezing rain and/or snow. Due to precipitation type questions, a heavy precipitation area was drawn on today's graphic and drawn large enough to encompass the spread in where the precipitation may fall. It's entirely possible that any impactful winter weather here will be light, if that's the case this area may be dropped in the next few days. For Alaska, extremely cold temperatures will be possible across the northeast portion of the state by Monday. Temperatures 20 to 30 degrees below average would equate to lows in the -30 to -40 degree range. These cold temperatures could sink south and east as well, but a large spread in forecast guidance kept the hazard area from extending in that direction for today. Moderate snow will be possible across the southern coast and Panhandle with a passing storm system on Saturday, but the forecast snowfall amounts at the moment are just under hazardous threshold. Snell