US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 441 PM EDT Mon Apr 08 2019 Valid Thursday April 11 2019 - Monday April 15 2019 Hazards: - Heavy precipitation across portions of the Pacific Northwest, Thu, Apr 11. - Heavy precipitation across portions of the Pacific Northwest and the Northern Great Basin, Sat-Mon, Apr 13-Apr 15. - Heavy precipitation across portions of the Central Rockies and the Central Great Basin, Fri-Sat, Apr 12-Apr 13. - Heavy precipitation across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Thu-Fri, Apr 11-Apr 12. - Heavy rain across portions of the Mid-Atlantic, the Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Northeast, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, Sat-Sun, Apr 13-Apr 14. - Heavy rain across portions of the Great Lakes and the Ohio Valley, Fri, Apr 12. - Heavy snow across portions of the Northern Rockies, Sun-Mon, Apr 14-Apr 15. - Heavy snow across portions of the Central Plains, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Thu-Fri, Apr 11-Apr 12. - Severe weather across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, the Great Lakes, the Ohio Valley, and the Tennessee Valley, Thu, Apr 11. - Flooding possible across portions of the Lower Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Northern Rockies, the Middle Mississippi Valley, the Northern Great Basin, the Upper Mississippi Valley, the Pacific Northwest, and the Ohio Valley. - Flooding likely across portions of the Northern Plains, the Tennessee Valley, the Pacific Northwest, the Northern Great Basin, the Upper Mississippi Valley, and the Southern Plains. - High winds across portions of the Central Plains, the Central Rockies, the Lower Mississippi Valley, the Northern Plains, the Southern Rockies, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southern Plains, and the Southwest, Thu, Apr 11. - Much below normal temperatures across portions of the Central Plains, the Central Rockies, the Northern Plains, the Southern Rockies, the Upper Mississippi Valley, and the Southern Plains, Thu-Sat, Apr 11-Apr 13. - Enhanced wildfire risk across portions of the the Southern Plains and the Southwest, Thu, Apr 11. - Heavy precipitation across portions of mainland Alaska and the Aleutians, Thu, Apr 11. - High winds across portions of mainland Alaska and the Aleutians, Thu, Apr 11. Detailed Summary: Thursday, April 11, will be the day when an intense low pressure system is forecast to spread heavy wet snow across the northern Plains into the upper Midwest where blizzard conditions are possible during the height of the storm. The snow should spread into the upper Great Lakes Thursday night while gradually tapering off over the northern Plains. There will be a zone along and just to the north of the storm track where heavy mixed precipitation can be expected. This is indicated by a strip of heavy precipitation on the hazards chart. In addition to the heavy wintry precipitation, heavy rain is possible from lower Michigan down into the Ohio Valley Thursday night ahead of a strong cold front, along with a chance of severe thunderstorms. During this potential blizzard, temperatures will be much below normal over the northern Plains into central High Plains Thursday and Friday. By Saturday, the cold air is expected to filter southward into the southern High Plains. The intense storm will also bring gale force winds and higher wind gusts across the southern Rockies into the High Plains early on Thursday. As the storm intensifies rapidly over the central Plains, high winds can be expected to develop to the north of the storm track in conjunction with heavy wet snow. An enhanced wildfire risk is indicated over the southern High Plains on Thursday as the intense storm drives Chinook winds down the eastern slopes of the southern Rockies. As the intense storm winds down on Friday, the next upper-level trough is forecast to move across the southern Rockies. This system is forecast to interact with the tail end of the cold front associated with the departing blizzard and will bring the potential of heavy rain into the western Gulf states on Saturday (Apr 14). Models are indicating a rather healthy injection of moisture from the Gulf of Mexico across the lower Mississippi Valley on Saturday, and possibly into the Ohio Valley by Sunday. There is a noticeable difference between the predicted storm track by the ECMWF and the GFS. The ECMWF shows a more stable solution with a more amplified upper-level pattern taking the storm more to the north-northeast toward the northeastern U.S., whereas the GFS takes the storm more to the east-northeast and pushes the storm off the Mid-Atlantic coast by next Monday (Apr 15). The heavy rain area indicated on the WPC hazards chart assumes a solution closer to the ECMWF and brings the heavy rain closer to New England by next Monday. Elsewhere, the western U.S. should become somewhat less active during the medium-range period with heavy precipitation possible only over the higher elevations of the Pacific Northwest, northwestern Wyoming, and southwestern Colorado. In Alaska, a rather intense occluded cyclone could bring high winds of over 50 mph toward the eastern Aleutian islands and the Alaska Peninsula on Thursday (Apr 11). Heavy rain can also be expected across much of the eastern Aleutians, into the Alaska Peninsula, and the south coast of Alaska on Thursday as the storm center and the associated occluded front pass through. In Hawaii, there appears to be a threat of heavy rain, especially on the eastern slopes of the Big Island and Maui, as an upper-level low drifts westward in the region, bringing higher instability under strong surface trade winds. Santorelli