Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 402 PM EDT Wed Sep 11 2019 Valid 00Z Thu Sep 12 2019 - 00Z Sat Sep 14 2019 ...There is a moderate risk of excessive rainfall over parts of the Upper Mississippi Valley and parts of the Northern/Central Plains... ...There is a slight risk of excessive rainfall over parts of the Northern High Plains... ...There is a slight risk of severe thunderstorms over the Great Lakes and Central Plains into parts of the Upper/Middle Mississippi Valley with an embedded enhanced risk over parts of the Central Plains... A strong wave of low pressure over the Central Plains will move northeastward to Southern Ontario by Friday evening. Showers and thunderstorms will develop along and ahead of the associated front over the Central Plains into parts of the Southern High plains that will move into the Great Lakes across parts of the Ohio Valley into Southern Plains by Friday evening. Some of the thunderstorms will be severe over parts of the Central Plains into parts of the Upper/Middle Mississippi Valley with the hazards of large hail, damaging wind gusts and a few tornadoes. A second area of severe thunderstorms will develop over parts of the Great Lakes with hazards of damaging winds and some hail through to Thursday morning for both areas. The associated rain will be heavy over parts of the Upper Mississippi Valley and parts of the Northern/Central Plains that produce an increase of the flood/flash flood potential. A stationary boundary set up from the Upper Great Lakes westward towards the northern High Plains will serve as a focus for potentially heavy rainfall and severe weather today. SPC shows a slight risk for severe thunderstorms along this boundary from southern Wisconsin to far southeast Wyoming, with an embedded enhanced risk across western Nebraska. WPC highlights parts of the Upper Midwest within a slight to moderate risk for excessive rainfall, with the potential for several inches of rain from northern Iowa/southern Minnesota into Wisconsin . An upper level trough across the western U.S. will advance eastward on Wednesday, eventually spinning up a robust surface low pressure system in the High Plains by early Thursday. Heavy to locally excessive rainfall is possible across parts of eastern Wyoming into the northern Plains on Wednesday. As this low lifts into the Upper Mississippi Valley on Thursday, another round of potentially heavy rainfall is expected from the Northern Plains to the Upper Great Lakes. Recent wet weather and saturated soils across this region will likely increase the flood/flash flood potential and WPC highlights much of the region within a slight risk for Thursday. This system will also drag a cold front across the Central Plains into the Mid-Mississippi Valley, with showers and thunderstorms and a threat for heavy rainfall and severe weather along the boundary as it progresses eastward Thursday into Friday. The deep troughing in the West will usher in an anomalously chilly air mass Wednesday and Thursday across the Northern Rockies into the Northern Plains with daytime highs 10 to 20 degrees below normal. As this system continues east into the Plains on Thursday, a warming trend can be expected across the West Coast states, with high temperatures returning into the 90s for the Central Valley of California. Meanwhile, east of the Rockies, upper level ridging will keep temperatures quite warm with daytime highs from the mid-80s to the mid-90s for many from the Mississippi Valley to the East Coast. These kinds of temperatures may approach or exceed record values, especially for parts of the Southern Appalachians. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php