US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 412 PM EDT Mon Nov 01 2021 Valid Thursday November 04 2021 - Monday November 08 2021 Hazards: - Heavy precipitation across portions of the Pacific Northwest and along the Cascades, Thu-Fri, Nov 4-Nov 5. - Heavy precipitation across portions of the Pacific Northwest and along the northern Cascades, Thu-Sun, Nov 4-Nov 7. - Heavy precipitation across portions of northern California into Oregon, Mon, Nov 8. - Flooding occurring or imminent across portions of central New York. - Flooding likely across portions of central Illinois. - Heavy precipitation across the eastern portion of the Kenai Peninsula, Thu, Nov 4. Detailed Summary: With an omega blocking pattern centered over western Canada, much of the eastern two-thirds of the country is forecast to be under the influence of an amplified and positively-tiled upper-level trough throughout the medium-range period. Underneath this upper trough, a large area of cool high pressure is expected to dominate the weather from the Plains eastward to much of the East Coast through the weekend and into early next week. The prospect of a rather robust cyclone forming near the East Coast, as indicated by previous ECMWF forecasts for this weekend, is not anticipated. The heavy rainfall ahead of the upper trough is expected to stay just off the Gulf Coast late this week, and then off the Southeast U.S. coast this weekend. Nevertheless, there remains some potential for cyclogenesis to occur near or off the East Coast this weekend under this amplified upper-level pattern. In any event, a large area of below normal temperatures is expected to extend across the Deep South to much of the East Coast through the weekend. Many locations are expected to experience their first freeze of the season from the central Plains eastward through the mid-Mississippi and Ohio Valleys, the lower Great Lakes into parts of the Northeast, as well as interior Mid-Atlantic/Appalachians. In addition, considerable cloudiness will keep temperatures rather cool in the afternoon over parts of these areas midweek. In contrast to the persistent trough and cool conditions in the East, a warm upper ridge will tend to re-establish itself across the Rockies into the northern Plains through the medium-range period. This will sustain a large area of warmer than normal temperatures for much of the interior western U.S. to the High Plains and into the northern Plains. Meanwhile, unsettled weather is forecast to continue across the Pacific Northwest as additional Pacific fronts and decaying low pressure systems edge toward the West Coast. It appears that coastal Pacific Northwest will be under the threat of heavy rain while the Cascades will be under the threat of heavy snow through midweek. A lull in the activities should restrict the heavy precipitation farther north across the region during the weekend. By next Monday, a more robust Pacific cyclone could approach the West Coast. The threat of heavy precipitation is indicated for northern California into southwestern Oregon at present. However, it may be necessary to extend the threat northward depending on the eventual track of this cyclone. Meanwhile, Alaska will remain situated west of the omega block where upper-level southerly flow will persist through the end of the week before the pattern shows signs of breaking down by the weekend. Under this pattern, heavy precipitation is forecast to continue across the eastern portion of the Kenai Peninsula through Thursday before tapering off. No significant storms are forecast to impact Alaska through the weekend into early next week. Much of the interior Mainland will experience above normal temperatures through early next week under the persistent southerly flow aloft. In contrast, cooler than normal conditions will prevail across the Southwest, the Aleutians, and along the Panhandle. A slow cooling trend is expected to spread across the entire area as the omega block in western Canada begins to break down. Kong