Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 345 PM EDT Sat Jun 17 2017 Valid 00Z Sun Jun 18 2017 - 00Z Tue Jun 20 2017 ...Severe thunderstorms and heavy rain possible from portions of the southern and central plains to the Northeast... ...Temperatures expected to reach dangerously hot levels across portions of the western U.S... An upper-level trough is forecast to amplify across the Great Lakes through the next couple days, helping to move a cold front from the plains and the Midwest to the East Coast states by Monday. Ahead of the front, a warm and unstable air mass is expected to support numerous showers and thunderstorms from the southern and central plains to the Upper Great Lakes tonight, to the Mississippi and Ohio valleys on Sunday, and into the eastern U.S. by Sunday night into Monday. Severe thunderstorms and heavy rainfall will be possible from portions of the southern and central plains to the Midwest, Ohio valley, Great Lakes, and Northeast through Monday. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. As the cold front moves south across the Plains, it will bring and end to the hot temperatures which have affected the region in recent days. High temperatures behind the front will be be near to slightly below average on Sunday and Monday, with only south Texas remaining in the warm air as the front becomes nearly stationary. High pressure aloft will expand across the western U.S. through Monday, with dry conditions and rising temperatures prevailing for most areas. Isolated showers or thunderstorms will be possible each afternoon and evening in mountainous areas. Temperatures will rise substantially across much of the West by Monday, with highs soaring well into the 90s from the interior West Coast states to the Great Basin, 10 to 20 degrees above average. Highs in the California Central Valley and across portions of the Desert Southwest may surpass 110 by Monday. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php