Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 459 PM EDT Wed Sep 18 2013 Valid 00Z Thu Sep 19 2013 - 00Z Sat Sep 21 2013 ...Strong to severe thunderstorms along with above normal temperatures are expected ahead of a frontal system as it pushes eastward across the northern and central U.S.... After a very cool morning in the Northeast, temperatures will gradually moderate as the high pressure center moves to the mid-Atlantic coast and southerly winds establish ahead of a strong cold front approaching from the northern Plains. A progressive upper-level trough will advance the cold front steadily across the Plains into the Midwest and the Great Lakes by Friday. Temperatures ahead of the front are expected to rise to more than 10 degree above normal. The warm temperatures and favorable upper-level dynamics will also help trigger showers and thunderstorms which could become severe in the northern Rockies today, and in the upper Midwest by tomorrow. The mid-Atlantic coast will remain fine under the influence of the cool high pressure system. However, unsettled weather is expected to continue in Florida as a moist and unstable airmass remains in place. Increasing tropical moisture from Mexico associated with tropical storm Manuel as well as from the cold front approaching from the north is expected to bring and increasing chance of showers and thunderstorms into Texas. In the northern Rockies, very cool air along with showers will begin to move eastward into the northern High Plains tonight and tomorrow. Meanwhile, moisture from the next Pacific front is expected to reach the Washington and Oregon coasts on Friday. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php