US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 237 PM EST Fri Jan 29 2021 Valid Monday February 01 2021 - Friday February 05 2021 Hazards: - Heavy precipitation across portions of the Mid-Atlantic and the Northeast, Mon-Tue, Feb 1-Feb 2. - Heavy rain across portions of California and the Pacific Northwest, Mon, Feb 1. - Heavy rain across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, the Ohio Valley, and the Tennessee Valley, Thu-Fri, Feb 4-Feb 5. - Heavy snow across portions of the Northeast, the Central Appalachians, the Northern Rockies, the Mid-Atlantic, California, the Northern Great Basin, the Central Great Basin, the Pacific Northwest, and the Southwest, Mon-Tue, Feb 1-Feb 2. - Heavy snow across portions of the Central Rockies, the Central Great Basin, the Northern Rockies, the Northern Great Basin, and the Northern Plains, Tue-Wed, Feb 2-Feb 3. - Heavy snow across portions of the Central Plains, the Central Rockies, the Central Great Basin, the Northern Plains, the Southern Rockies, the Southern Plains, and the Southwest, Wed, Feb 3. - Heavy snow across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Wed-Fri, Feb 3-Feb 5. - Flooding possible across portions of the Middle Mississippi Valley. - High winds across portions of the Central Plains, the Central Rockies, the Northern Plains, the Southern Rockies, the Southern Plains, and the Southwest, Wed-Thu, Feb 3-Feb 4. Detailed Summary: The medium range period (Monday, February 1st to Friday, February 5th) contains a plethora of hazards from coast to coast with two main system impacting the Continental United States. Starting in the East on Monday, a low pressure system is expected to strengthen off the Delmarva Peninsula and very slowly move toward the northeast. Wintry precipitation will already be occurring across the Mid-Atlantic and will be in the process of spreading up the coast from Long Island to New England late Monday into Tuesday. There remains a relatively large spread on exactly how far inland the heavy snow reaches, but confidence is growing that enough snow will fall between northern Virginia and coastal New England to meet warning level criteria. A few locations may even approach a foot of total snowfall depending on where the pivoting band of heavy snow develops. This includes several major cities from Washington D.C. to Boston. Areas from southern Maryland to Delaware, as well as Cape Cod, will have the potential for a mixture of heavy rain and snow as warmer air infiltrates closer to the low pressure center. There also remains the possibility for gusty winds and coastal flooding from New Jersey to New England as strong east-northeast winds swing around the center of the storm. By Wednesday morning much of the snow should come to a gradual close across New England, with only gusty northwest winds to contend with. Meanwhile, the next system to cross the Lower 48 will be responsible for heavy rain and mountain snow throughout much of northern California and the Sierra Nevada to start the week. Precipitation amounts will not be nearly as high as what was seen the last 5 days, but nonetheless more heavy snow is on the way. By Tuesday, impacts will reach the northern Rockies and Intermountain West in the form of higher elevation heavy snow. As upper level energy reaches the Plains by Thursday, cyclogenesis should occur across the central Plains as an area of low pressure develops. Heavy snow will be possible across the central Rockies and High Plains from northern Colorado to central Wyoming during this time frame. Strong winds will also accompany the system and associated Pacific cold front on Wednesday and Thursday from the Southern Rockies to Central Plains. Forecast models offer several possibilities as the storm tracks to the northeast across the Midwest and Great Lakes by Friday. The greatest probability for heavy snow from mid-to-late week remains across the eastern Dakotas, Nebraska, and into the Upper Midwest/Great Lakes region. It is also possible gusty winds could accompany this snow, but given the higher than average uncertainty an area was not added to the hazards graphic today. As the cold front pushes through the Lower Mississippi Valley on Thursday, heavy rain and thunderstorms may develop across the Tennessee Valley and Southern Appalachians by the end of the week. Rainfall amounts over an inch will be possible and could pose a slight flash flooding risk, particularly along the typical upslope regions of the southern Appalachians. Temperatures across the Lower 48 will flip flop throughout the week, with below average temperatures in the eastern U.S. on Monday and Tuesday before flipping to above average to end the week. The opposite will be found across the central and western United States. In fact, high temperatures on Friday could be 10 to 15 degrees below average across the northern High Plains. An area highlighting much below average temperatures may be needed here during the next graphic update. Across Alaska, a potent cold front will bring the potential for gusty winds early next week across southwest portions of the state. These gusts appear to remain below hazardous threshold at the moment, therefor no area was needed on the hazards graphic today. Otherwise, below average temperatures will be easy to find at the beginning of the period before moderating by Friday Snell