Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Thu Sep 26 2013 Valid 00Z Fri Sep 27 2013 - 00Z Sun Sep 29 2013 ...Heavy rain possible over the Pacific Northwest... ...Heavy rain possible from parts of the Central Plains to the Upper Mississippi Valley... ...Temperatures will be 10 to 15 degrees above average from the Upper Great Lakes to part of the Middle Mississippi Valley, in contrast, temperatures will be 10 to 20 degrees below average from the Northern/Central High Plains to the Great Basin/Central Rockies... A front extending from the Northern Plains to the Great Basin/Southwest will slowly advance eastward to the Upper Mississippi Valley/Southern High Plains by Saturday morning. Strong upper-level dynamics in deep upper-level trough will produce higher elevation snow and lower elevation rain over parts of the Northern/Central Rockies and parts of the Great Basin through Friday evening. As the boundary moves onto the Plains, moisture from the Western Gulf of Mexico will stream northward over the Plains/Mississippi Valley and pool along the front. Showers and thunderstorm will develop along and ahead of the boundary over the Middle Missouri Valley/Upper Mississippi Valley early Friday morning while expanding southward along the front to the Southern Plains. Behind the front, rain will develop over parts of the Northern Plains moving eastward to the Upper/Middle Mississippi Valley by Saturday morning. Meanwhile, a wave of low pressure along a front over the Eastern Gulf Coast/Southeast Coast will steadily move eastward out over the Atlantic. Showers and thunderstorms will develop along the boundary and also associated with easterly flow off the Atlantic over the Southern tip of Florida as well as Florida's east coast through Saturday. An approaching Pacific front will influence the weather along the Pacific Northwest Coast producing light rain starting overnight Thursday that will expand inland as far as the Northern Rockies by Friday afternoon/evening. The rain will become moderate to heavy by Saturday morning along the Northwest Coast. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php