Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 310 AM EDT Tue May 30 2017 Valid 12Z Tue May 30 2017 - 12Z Thu Jun 01 2017 ...Severe thunderstorms and locally heavy rain possible today for portions of the Mid-Atlantic and Northeast... ...Above average temperatures expected to shift east from the Pacific Northwest to the northern Rockies... A frontal system will bring scattered to numerous showers and thunderstorms to much of the Mid-Atlantic and Northeast today. Some thunderstorms could be severe; please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. Locally heavy rainfall is also possible. Another round of scattered showers and storms is possible on Wednesday for the same areas as a secondary cold approaches the region and an upper-level disturbance passes overhead. As this secondary cold front passes through Wednesday night and Thursday morning, high pressure will move into the Great Lakes and Northeast behind it, ushering in a drier and somewhat cooler air mass. Farther south, the trailing end of the frontal boundary will linger as a stationary front from Texas to the Southeast, producing scattered showers and thunderstorms over a wide area today through Thursday. The ridge of high pressure aloft that has resulted in temperatures soaring well into 90s for interior portions of the Pacific Northwest will begin to move east today. Temperatures will once again rise into 90s across the interior Northwest and northern Great Basin today. The Northwest will cool by Wednesday as an upper-level trough begins to move into the region, and a weak cold front ushers in a cooler Pacific air mass. The above average temperatures will shift east on Wednesday along with the upper-level ridge, and high temperatures will rise well into the 70s and 80s across much of the northern Rockies, 10 to 15 degrees above average. Scattered showers and thunderstorms will be possible as well from the Northwest to the northern Rockies, especially ahead of the aforementioned cold front as it moves inland on Wednesday and Thursday. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php