Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 328 AM EDT Sat Sep 23 2017 Valid 12Z Sat Sep 23 2017 - 12Z Mon Sep 25 2017 ...Cold for the western U.S. and warm for the eastern states... A dichotomy of air masses will exist across the nation this weekend, with a deep trough over the Intermountain West and a large upper level ridge over the eastern U.S. This equates to below normal temperatures and some snow for the highest elevations of the Rockies, and summer-like heat and noticeable levels of humidity from the Plains to the East Coast. Some locations could even achieve record high temperatures with readings breaking the 90-degree mark. Widespread areas will see temperatures running 10 to 20 degrees above normal for this time of year. Given the pronounced difference in these air masses, a strong frontal boundary will exist from the central Rockies to the Upper Midwest, with very slow eastward progression over the next couple of days. Some strong to severe thunderstorms are expected to develop along and ahead of the front across the western High Plains, and also for parts of the Upper Midwest on Saturday. In addition, these storms will be capable of producing episodes of heavy rain that could result in flash flooding. Across the eastern U.S., the effects of post Tropical Storm Jose will continue to diminish as this system weakens. The attention now turns to Hurricane Maria and its future path, and the National Hurricane Center has additional details on that storm. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php