US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 314 PM EDT Mon Jun 08 2020 Valid Thursday June 11 2020 - Monday June 15 2020 Hazards: - Heavy rain across portions of the Southeast and the Mid-Atlantic, Thu-Fri, Jun 11-Jun 12. - Heavy rain across portions of the Southeast, Sat-Mon, Jun 13-Jun 15. - Flooding possible across portions of the Lower Mississippi Valley, the Northern Rockies, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southeast, the Great Lakes, and the Ohio Valley. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern Plains, the Northern Rockies, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Southeast. - Flooding likely across portions of the Southeast and the Lower Mississippi Valley. - High winds across portions of the Central Great Basin, the Northern Great Basin, and the Southwest, Fri, Jun 12. - High winds across portions of the Central Plains, the Central Rockies, the Central Great Basin, the Northern Plains, the Southern Rockies, and the Southwest, Sat, Jun 13. - High winds across portions of the Great Lakes, Thu, Jun 11. - Enhanced wildfire risk across portions of the the Central Great Basin and the Southwest, Fri, Jun 12. - Enhanced wildfire risk across portions of the the Central Great Basin and the Southwest, Sat, Jun 13. - Much above normal temperatures across portions of mainland Alaska, Thu-Sun, Jun 11-Jun 14. Detailed Summary: The weather pattern during the medium-range period (Thurs Jun 11 - Mon Jun 15) features a wavy jet stream with an upper level trough over the Pacific Northwest, ridging across the Plains, another trough over the Great Lakes, and a corresponding ridge over the eastern Canadian Maritime. One of the key storm systems of the period is Post-Tropical Cyclone Cristobal as it becomes very intense over eastern Ontario. Guidance shows at 12Z Thursday the storm with a minimum MSLP that is 3 to 4 standard deviations below normal. Combined with a large dome of high pressure over the South Central U.S., the tight pressure gradient overhead could lead to high winds, especially over the open waters and along the coasts of the northern Great Lakes where rough waters are also possible. Rainfall from both the storm system and an anomalously wet spring led to overly saturated soils in the region, which could aid in the increased potential for tree damage and power outages. River flooding is also possible the first half of the period across much of the Mississippi River Valley. Ahead of the storm system, expect a very warm and humid Thursday and Friday but cooler conditions arrive in time for the weekend. As drier northwesterly flow infiltrates the U.S. along with a lack of moist southerly flow from the Gulf of Mexico, much of the Lower 48 can anticipate drier than normal conditions. That said, there are still a few locations that can expect wetter than normal conditions. Most notably this Thursday and Friday, a slow moving cold front looks to be come nearly stationary over the Southeast. High moisture content is expected over the region and with the front acting as a trigger, heavy showers and thunderstorms could produce excessive rainfall rates. Soil in the Carolinas and Georgia also remain overly saturated after a very wet May, giving rise to flash flood opportunities late week. In addition, a weak upper level trough and elevated moisture aloft will make for a wet and stormy weekend in South Florida and into early next week. Farther west, the Pacific Northwest will also contend with abnormally wet conditions with the heaviest rainfall occurring in the Cascade and Olympic mountain ranges but confidence in whether amounts reach heavy rain criteria is low at this time. In contrast, much drier conditions along with strong winds and very low humidity levels over the Four Corners region are possible as a strong upper trough swings through the Great Basin and Intermountain West Friday and into the weekend. Both high wind and enhanced fire risks areas are in place along with a separate area for strong winds in the northern High Plains on Saturday Over Alaska, much warmer than normal temperatures look to develop across the northwestern part of the state with the potential for near threshold warmth over the northern-most regions. Meanwhile, topographically-induced/enhanced precipitation is also expected to linger across the mainland each afternoon throughout the interior. Fire potential is most concerning in the Yukon Flats but increased thunderstorm potential, particularly in central Alaska, along thermal troughs running through mainland Alaska compounded by parched/favorable fuels could spark a number of starts. Mullinax