US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 339 PM EDT Mon Sep 28 2020 Valid Thursday October 01 2020 - Monday October 05 2020 Hazards: - Heavy rain across portions of the Southeast, Thu-Sat, Oct 1-Oct 3. - Flooding occurring or imminent across portions of the Southeast. - Much above normal temperatures across portions of California, the Pacific Northwest, and the Great Basin, Thu-Sat, Oct 1-Oct 3. - Much below normal temperatures across portions of the Central/Northern Plains, the Middle/Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Fri-Sat, Oct 2-Oct 3. - Heavy precipitation across portions of mainland Alaska, Thu-Sat, Oct 1-Oct 3. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Fri, Oct 2 and Sun-Mon, Oct 4-Oct 5. - Heavy precipitation across portions of mainland Alaska, Thu-Mon, Oct 1-Oct 5. - High winds across portions of mainland Alaska, Thu-Fri, Oct 1-Oct 2. Detailed Summary: During the medium range period (Thursday, Oct 1 - Monday, Oct 5), a deep upper-level trough will be slow-moving across the central to eastern U.S., while upper-level ridging is persistent across the West. This upper-level pattern should lead to warmer than average temperatures by 5 to 15 degrees across the West Coast into the Desert Southwest and Great Basin, and a handful of record warm lows and highs could be set. The most hazardous conditions are likely across the valleys of California into southern Oregon, where much warmer than normal temperatures in the 90s are forecast. The Desert Southwest can expect highs above 100 degrees, about 5 to 10 degrees above average for this time of year. Highs in the 70s and 80s for the Great Basin and the Pacific Northwest are not considered hazardous, but are above normal as well. On the other hand, cooler than normal temperatures are forecast for the central to eastern U.S. underneath the upper-level trough and behind a couple of cold fronts. High temperatures should be 10 to 15 degrees below average from the Northern/Central Plains across the Mississippi Valley toward the Great Lakes and Tennessee/Ohio Valleys through the weekend, with lesser cool anomalies toward the East Coast. In terms of low temperatures, Friday and Saturday mornings look to be the most below normal, and an area of Much Below Normal Temperatures was delineated on the Hazards graphic across portions of the Northern/Central Plains to the Upper Midwest and Ohio Valley, where morning low temperatures could get into the 30s and cause the first frost or freeze of the season. This seemed to be the most hazardous aspect of these temperatures more reminiscent of mid- or late fall. Most of the contiguous U.S. should have generally light to no precipitation during the period. The main exception will be southern Florida, where fronts could linger and cause locally heavy rain through the end of the week at least. There is some signal in the model guidance for heavier precipitation in central to northern Florida for the weekend into early next week as well, which will continue to be monitored. The initial cold front pushing through Florida could cause record low temperatures Thursday morning in the peninsula. With dry, warm conditions in the West, additional fire weather concerns may develop. Over Alaska, heavy precipitation is forecast along the Gulf of Alaska coast in the vicinity of potent surface lows. An initial low pressure system should spread heavy precipitation across the south-central part of the state through the end of the week, and high winds near Bristol Bay toward the Kenai Peninsula Thursday/Friday. Moist onshore flow from this system could bring a round of heavy rain farther east toward the panhandle Friday, and there is some potential for high wave heights south of the Kenai Peninsula and south of Prince William Sound on Friday as well. Then, another low system moving through the Gulf of Alaska early next week should provide additional chances for heavy precipitation for the Gulf coast for the first part of next week. Farther north in interior Alaska, above normal temperatures are forecast, with highs approaching 60 degrees. Tate