US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 341 PM EST Fri Jan 15 2021 Valid Monday January 18 2021 - Friday January 22 2021 Hazards: - Flooding occurring or imminent across portions of the Southeast and the Pacific Northwest. - High winds across portions of the Central Great Basin, California, and the Southwest, Mon-Tue, Jan 18-Jan 19. - High winds across portions of the Northern Plains and the Northern Rockies, Tue, Jan 19. - High winds across portions of the Central Rockies and the Central Plains, Wed, Jan 20. - Heavy rain across portions of the Southern Plains, the Lower Mississippi Valley, the Tennessee Valley, the Southern Appalachians, and the Southeast, Thu-Fri, Jan 21-Jan 22. - Enhanced wildfire risk across portions of California, Mon-Tue, Jan 18-Jan 19. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 18. - High winds across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 18. Detailed Summary: Throughout the medium range period (Monday, January 18 - Friday, January 22) the upper-level pattern will be dominated by the emergence of a deep cut-off low over the Southwest embedded within significant southwest-northeast oriented troughing. As this pattern develops, a low pressure/frontal system moving south through the Central Plains is forecast to bring snow to the Rockies on Monday, the heaviest of which is anticipated to fall in Colorado. High elevation snow is also expected to fall over the Colorado Plateau in northern Arizona on Tuesday. Simultaneously, high pressure building to the northwest of this system will begin moving southeast Monday evening, tightening the pressure gradient over the western states. The strongest tightening is expected to occur over California and the Southwest Monday into Tuesday, generating hazardous wind gusts that can reach up to 50kts in the Sierra Nevada and Los Angeles metro area. These high winds, dangerous enough on their own, will also contribute to enhanced wildfire risk in southern California extending from Los Angeles to the Mexico border. Tuesday evening into Wednesday morning a low pressure/frontal system descending from central to southern Canada will bring high winds to the Lewis Range in Montana and the Wyoming/Colorado Front Range as well as another round of snow for the Rockies. The highest totals will likely fall over the Colorado Rockies and Salmon River Mountains in Idaho, however, they are not expected to reach hazardous levels. On Thursday another low pressure/frontal system moving onshore from the Pacific will bring snow to the Oregon and Washington Cascades. Late next week a separate low pressure/frontal system that had been hovering over Texas will begin to propagate northeast on Thursday. Moisture pulled inland from the Gulf of Mexico by the system will combine with strong frontogenetical forcing over the South to produce heavy rain in the region Thursday and Friday, with rainfall rates that may reach 1.5+" in 24hrs in some areas. Throughout the course of the medium range period maximum temperatures over the CONUS will remain relatively normal, save for Wednesday when the Northern Great Plains could see daily highs 15-20 degrees above normal. Conversely, minimum temperatures virtually everywhere within the lower 48 will see above normal daily lows at least once during the period. None of these temperature departures are expected to be hazardous. In Alaska, much of the activity in the medium range will occur on Friday when a strong low pressure/frontal system passes through the Gulf of Alaska, bringing heavy precipitation to the Southcentral mainland and Alaska Panhandle. While most of the precipitation is expected to fall on Friday, some is expected to linger into Saturday morning over the southern Panhandle. Onshore winds associated with this system may pose a threat to coastal regions, specifically the southern mainland and northern Panhandle, where wind gusts are expected to reach hazardous levels. While this system may generate significant waves, they will remain predominantly offshore. Over the course of the period maximum and minimum temperatures are forecast to be well above normal throughout mainland Alaska. While maximum temperatures may reach 30F above normal, bringing some daily highs in the Southwest mainland above freezing Thursday and Friday, minimum temperatures in some areas will likely reach or exceed 40F above normal! Zavadoff