US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 423 PM EDT Thu Nov 04 2021 Valid Sunday November 07 2021 - Thursday November 11 2021 Hazards: - Heavy rain across portions of California and the Pacific Northwest, Mon-Wed, Nov 8-Nov 10. - Heavy snow across portions of California, the Central Great Basin, the Pacific Northwest, and the Northern Great Basin, Mon-Wed, Nov 8-Nov 10. - 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, Nov 9-Nov 10. - Flooding occurring or imminent across portions of the Northeast and the Great Lakes. - Flooding occurring or imminent across portions of the Northeast and the Great Lakes. - Flooding occurring or imminent across portions of the Northeast. - Flooding likely across portions of the Middle Mississippi Valley. - Flooding likely across portions of the Middle Mississippi Valley. - Flooding likely across portions of the Middle Mississippi Valley. - High winds across portions of the Mid-Atlantic, Sun, Nov 7. Detailed Summary: During this upcoming medium range period (Sunday, November 7th - Thursday, November 11th), an active Pacific storm track will focus much of the active weather over the Pacific Northwest and northern California. A lead storm pivoting through eastern Pacific upper-troughing will produce moderate rain and accumulating elevation snow beginning this weekend which spills into Day 3 over the Pacific Northwest. General medium range shortwave timing differences remain with the forecast, but reasonable agreement exists that the influx of Pacific moisture should stay weak, which will limit hazardous precipitation potential on Sunday. The more impactful storm system is expected to arrive over the Pacific Northwest early next week, this time with better Pacific moisture and more robust onshore flow to support moderate to locally heavy rainfall and heavy mountain snows over the Sierra Nevada and Cascade Range beginning Monday. The precipitation will extend east into the Bitterroot and Absaroka Range by Tuesday to support moderate to locally heavy mountain snowfall through midweek. Afterwards, unsettled conditions are expected to remain over the Pacific Northwest as low pressure lingers off the British Colombia coast. The potential for heavy rain will spread east into the Midwest by the end of next week, as moist southerly inflow from the Gulf of Mexico increases ahead of the approaching Pacific frontal system. However, growing model disagreement regarding the timing and amplification of the pattern beyond Day 4 limits confidence in a Heavy Rain area for now. Farther east, a coastal low is forecast to track well east of the Mid-Atlantic coastline on Day 3. Heavy rain impacts are anticipated to remain offshore, although the Outer Banks of North Carolina may receive a brief glancing blow of moderate rain Sunday as the system tracks northeast. Moreover, the tight gradient between high pressure over the Tennessee Valley and the developing cyclone will result in strong winds along the Outer Banks of North Carolina on Sunday. Overall impacts from this system are expected to quickly wane as this storm tracks further into the Atlantic, however. Otherwise, no temperature related hazards are anticipated over the medium range. In general, high temperatures west of the Four Corners are forecast to remain at or slightly below normal over the medium range behind a series of Pacific cold fronts. A general warming trend will spread eastward from the West-Central U.S. to the Northeast through midweek beneath a subtropical ridge, before the aforementioned cold fronts push through and reset highs to around average. Alaska remains fairly quiet through the medium range, as much of the unsettled weather will track south south of the state. Some gusty winds are possible across the Aleutians Monday and Tuesday as low pressure skirts to the south, but are not expected to reach hazardous levels. After a warm weekend, an overall cooling trend over all of Alaska will persist through the medium range as an upper-trough re-establishes overhead. Asherman