US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 347 PM EST Wed Dec 16 2020 Valid Saturday December 19 2020 - Wednesday December 23 2020 Hazards: - Heavy precipitation across portions of the Pacific Northwest, Sat-Mon, Dec 19-Dec 21. - Heavy snow across portions of the northern Rockies, Sat-Mon, Dec 19-Dec 21. - Flooding possible across portions of the coastal plain in northwestern Washington. - High winds across portions of the northern Rockies, Sat-Mon, Dec 19-Dec 21. - Heavy precipitation across the Alaska Peninsula, Mon, Dec 21. - Heavy precipitation across portions of southern Alaska, Tue-Wed, Dec 22-Dec 23. - Heavy precipitation across portions of the Alaska Panhandle into southern Alaska, Wed, Dec 23. - Heavy snow across the eastern portion of the Alaska Panhandle, Sat, Dec 19. - High winds across the Alaska Peninsula into southern Alaska, Mon-Tue, Dec 21-Dec 22. - Much below normal temperatures across much of the lower elevations of eastern Alaska, Sat-Tue, Dec 19-Dec 22. Detailed Summary: The active onshore flow pattern across the Pacific Northwest will continue into the medium range period (Saturday, Dec 19 - Wednesday, Dec 23), as additional moisture-laden and energetic frontal systems are forecast to impact the area with heavy rain for the lower elevations while heavy snow will continue to blanket the Coastal Ranges as well as the Oregon and Washington Cascades. Further inland, heavy snow can be expected across the northern Rockies in Idaho, northeastern Oregon, and western Montana through this weekend and into Monday. In addition, winds across parts of the eastern slopes of the northern Rockies could experience very strong Chinook winds this weekend and into Monday as the main frontal system exits into the northern High Plains. By the middle of next week, it appears that the Pacific Northwest will catch a break from the active weather. Along the Gulf Coast, a developing low pressure along a coastal front will bring an increasing chance of rain across the region. It appears that the rain will not be heavy enough to warrant a heavy rain area at this time. Temperature-wise, the active zonal flow from the Pacific will result in above to well above normal temperatures across the northern tier states into the central Plains throughout the medium range period, with temperatures ranging anywhere from 10 to 25 degrees above normal. Though anomalous, these temperatures are not expected to be hazardous. Meanwhile, the active synoptic pattern over the northeastern Pacific will continue to direct large and energetic cyclones downstream toward Alaska during the medium range period. As the heavy snow associated with a weakening cyclone begins to wind down across the Alaska Panhandle on Saturday, a rather large and energetic cyclone is forecast to approach the Aleutians with widespread gale to storm force winds and heavy precipitation. This system will likely bring high winds and heavy precipitation from west to east across the Alaska Panhandle during the weekend, before reaching the southern portion of Alaska next Monday and continue into Wednesday. In addition, some of the heavy precipitation from this system is forecast to reach the Alaska Panhandle on Wednesday. Farther inland across the lower elevations of eastern Alaska, much below average high and low temperatures are expected to continue through this weekend into early next week, where temperatures are expected to reach as low as -35 to -40F. Kong