US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 424 PM EDT Fri Oct 29 2021 Valid Monday November 1 2021 - Friday November 05 2021 Hazards: - Heavy precipitation across portions of the Central Great Basin and California, Wed-Thu, Nov 3-Nov 4. - Heavy rain across portions of California, the Lower Mississippi Valley, the Pacific Northwest, and the Southern Plains, Wed, Nov 3. - Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Tue, Nov 2. - Flooding possible across portions of the Mid-Atlantic and the Northeast. - Flooding occurring or imminent across portions of the Northeast, the Great Lakes, the Lower Mississippi Valley, the Pacific Northwest, and the Northern Great Basin. - Flooding likely across portions of the Middle Mississippi Valley and the Mid-Atlantic. - Much below normal temperatures across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley, Mon-Thu, Nov 1-Nov 4. - Heavy precipitation across portions of mainland Alaska, Mon-Tue, Nov 1-Nov 2. - Heavy precipitation across portions of mainland Alaska, Wed-Thu, Nov 3-Nov 4. Detailed Summary: The weather pattern over most of North America will be featured by a large upper level ridge over western Canada aiding in the development of downstream troughing over the Upper Midwest and Great Lakes. The resulting temperature pattern is for cooler than normal temperatures from the High Plains to the Ohio Valley and Midwest for much of next week. The coldest temperature anomalies are forecast to be from the Central Plains to the lower Ohio Valley, with the potential for some first frost/freezes of the season. This, combined with daily temperature anomalies approaching 10-15 degrees below normal for multiple days, has resulted in the continuation of a Much Below Normal temperature outlook area for these regions. In terms of precipitation hazards, an elongated frontal boundary stretching from the Four Corners region and Southern Plains to the Mid-South becomes the focal point for active weather for the first half of next week. As an upper level disturbance exits the Intermountain West, precipitation will blossom along the front, leading to periods of heavy rain and even thunderstorms on Tuesday (11/2) across the Southern Plains. By Wednesday (11/3), the heaviest precipitation advances east into the Lower Mississippi Valley with trailing convection possible into eastern Texas. Additionally, the West Coast will continue to be susceptible to stretches of wet weather owing to the very active North Pacific jet stream pattern. The heaviest round of precipitation for the period arrives Wednesday and Thursday (11/3-11/4). The trough will be deeper and be more supportive of generating heavy mountain snow in the northern and central Sierra Nevada, with heavy rain along the lower elevation slopes. This is likely shaping up to be another atmospheric river setup across this region, although there remains some uncertainty in placement specifics. This continues to be a welcome sight for the drought-stricken West, but should excessive rainfall rates materialize, flash flooding near burn scar areas would be possible. In Alaska, more wet, wintry, and windy weather is expected from the Alaskan Peninsula to near the southwest Yukon border into early next week as a strong and slow moving low pressure system meanders over the Gulf of Alaska. Increased moisture streaming inland ahead of the system will fuel heavy rain at lower elevations and significant mountain snowfall. This includes the Alaska Range, Chugach Mountains and the Kenai Peninsula. On the southern periphery of this storm, a Pacific cyclone, carrying the remnant moisture of Typhoon Malou, will also track towards the Panhandle by mid-week. There is still enough uncertainty and spread in ensemble guidance that exact impacts and where they occur are too low of confidence to add threat areas at this time, but it could mean soaking rainfall and gusty winds for the Panhandle towards the middle of the week. Hamrick/Mullinax