US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 318 PM EDT Wed Sep 25 2019 Valid Saturday September 28 2019 - Wednesday October 02 2019 Hazards: - Heavy precipitation across portions of the Northern Rockies and the Northern Plains, Sat-Sun, Sep 28-Sep 29. - Heavy rain across portions of the Central Plains to the Upper Midwest, Mon-Wed, Sep 30-Oct 2. - Heavy rain across portions of the Upper Mississippi Valley, Sun, Sep 29. - Flooding possible across portions of the Middle Mississippi Valley and Upper Midwest. - Flooding occurring or imminent across portions of the Mississippi River Valley. - Flooding likely across portions of the Middle Mississippi Valley and the Southern Plains. - Much above normal temperatures across portions of the Southeast, the Ohio Valley, and the Mid-Atlantic, Sat-Wed, Sep 28-Oct 2. - Much below normal temperatures across portions of the Central Great Basin to the Northern Plains, Sat-Wed, Sep 28-Oct 2. - Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Sun-Tue, Sep 29-Oct 1. Detailed Summary: The upper level flow pattern during the medium range period (Saturday to Tuesday) continues to be highly amplified. This features an anomalous upper trough over the West, and an upper ridge over the East. Temperatures under the trough will be much below normal across a broad area from the Great Basin to the Northern High Plains, where daytime highs could be 10 to 25 degrees below normal and locally 25 to 35 below normal especially across parts of Montana. Morning lows are also expected to be below normal, though not to the extreme as the daytime highs. Meanwhile in the East, daytime highs could be 10 to 25 degrees above normal for many east of the Mississippi but these kinds of temperatures may not necessarily be considered hazardous. The exception is from the Deep South to the lower Ohio Valley and Mid-Atlantic where daytime highs in the mid to upper 90s may come close to or exceed daily high temperature records. For this reason, a much above normal temperatures hazard area was included for this region. In between, plenty of moisture will be funneled northward into the Plains region to produce a couple of regions of concern for heavy precipitation/rain. An area of heavy rain (and mountain snow) is likely to the north of a surface low as it drifts across the Rockies into the Plains this weekend. Several feet of snow is possible in the highest terrain, though meaningful snow may also spill over into the lower elevations as well. Heavy rainfall is also possible into parts of the northern High Plains, but for simplicity reasons, opted to just include all of this region (from the Northern Rockies to High Plains) within a broad heavy precipitation area. As this system moves into the Plains early next week, heavy rainfall is possible initially across parts Minnesota into northern Wisconsin/U.P. of Michigan on Sunday. The attendant cold front may slow or stall across the Central Plains to the Upper Midwest/Great Lakes Monday-Wednesday which would provide an additional focus for heavy rainfall. Models advertise several inches of rain could be possible within this corridor. In Alaska, a system moving into the Gulf of Alaska early next week should bring a threat for heavy rainfall across the southern Coast region into northern parts of the Panhandle. Much of this should be rain, though some snow (probably below hazard criteria) is possible in the highest terrain. In Hawaii, an axis of tropical moisture is forecast to settle in across the western islands later this week and into this weekend. This could bring daily and locally enhanced heavy rainfall potential. Santorelli