US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 335 PM EDT Fri Apr 05 2019 Valid Monday April 08 2019 - Friday April 12 2019 Hazards: - Heavy precipitation across portions of California and the Pacific Northwest, Mon, Apr 8. - Heavy precipitation from portions of the Central Great Basin and Rockies to the Upper Midwest, Tue-Thu, Apr 9-Apr 11. - Heavy precipitation across portions of the Northern Rockies, Mon-Tue, Apr 8-Apr 9. - Heavy rain across portions of Central Plains and Upper Midwest, Wed-Thu, Apr 10-Apr 11. - Heavy rain across portions of the Gulf Coast and the Southern Appalachians, Mon, Apr 8. - Heavy snow across portions of the Northeast, Mon, Apr 8. - Flooding possible across portions of the Northern Great Basin. - Flooding occurring or imminent across portions of the Mississippi and Missouri River Basins. - Flooding likely across portions of the Missouri River Basin and the Upper Mississippi Valley. - High winds across portions of the Southern Rockies and the Southern and Central High Plains, Tue-Thu, Apr 9-Apr 11. - Enhanced wildfire risk across portions of the the Southern Rockies, the Southern Plains, and the Southwest, Wed, Apr 10. - Heavy precipitation across portions of the Alaska Panhandle, mainland Alaska, and the Aleutians, Wed-Fri, Apr 10-Apr 12. - High winds across portions of mainland Alaska and the Aleutians, Wed-Thu, Apr 10-Apr 11. Detailed Summary: Gulf of Mexico moisture streaming northward ahead of a cold frontal boundary moving across the Plains and Mississippi Valley this weekend will continue a threat for heavy rainfall at the beginning of the medium range period. The heaviest amounts and most likely areas for significant rainfall should focus across the Southern Appalachians and parts of the central Gulf Coast on Monday. The front will continue a steady progression into the eastern U.S. Monday into Tuesday, and the guidance indicates the potential for heavy rainfall extending into parts of the Ohio Valley and the northern Mid-Atlantic states, but given some uncertainty in rainfall amounts, left those regions out of a heavy rainfall hazard. There is also likely to be accumulating snowfall across parts of interior New England/Northern Maine associated with this system, and a heavy snowfall hazard was added today. An upper level low entering the Pacific Northwest by the end of this weekend will bring another round of heavy rain and higher elevation snows to parts of the Pacific Northwest and Northern California through Monday. Heavy precipitation (terrain-enhanced rain and mountain snows) pushes eastward Monday-Tuesday into the northern Great Basin and parts of the northern/central Rockies. Models show the development of a potentially deep surface low across the Central Plains by next Wednesday, with uncertainty beyond with respect to timing and placement. To the north and west of the low, an expansive area of heavy precipitation is likely to shift eastward from the Central Rockies, through the north-central Plains and into parts of the Upper Midwest Tue-Thur next week. Precipitation in the higher terrain should be mostly snow, with rain in the lower elevations. Across the Plains and Upper Midwest, it is possible there could be a thin axis of mostly snowfall along the northern edge of the precipitation shield, with rain changing to snow elsewhere. A heavy rainfall hazard area was included just south of the heavy precipitation area from eastern Nebraska to southern Wisconsin/northern Illinois where the predominant precipitation type is likely to be rain. Rainfall from this storm across the Mississippi and Missouri river basins may exacerbate ongoing flooding concerns and should be monitored closely. In addition to precipitation threats, models show better agreement on a region of high winds associated with this system from the Southern Rockies to the Southern and Central High Plains next Tuesday to Thursday. In the Southwest, an upper ridge will build early next week, potentially bringing the first 100 degree temperatures of the season to the Desert Southwest. While this may be 10-15 degrees above normal, it does not represent a significant hazard as the air mass is very dry and the warm temperatures will be short-lived, lasting just Monday and Tuesday before temperatures cool closer to normal on Wednesday. 90 to near 100 degree heat shifts to parts of the southern Rockies/High Plains Tuesday into Wednesday as well and combined with gusty winds behind the strong storm in the central U.S., may result in an enhanced wildfire risk. In Alaska, the main system of concern is with a very deep cyclone tracking across the Aleutians and into the Bering Sea during the middle to latter part of next week. This is likely to bring the potential for high winds and heavy precipitation across much of the Aleutians, and into the Peninsula and parts of the southern Coast, including St Lawrence Island and the Prince William Sound. Santorelli