Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 332 AM EDT Wed Sep 16 2015 Valid 12Z Wed Sep 16 2015 - 12Z Fri Sep 18 2015 ...Heavy rain possible off the East and West Coast of Florida... ...Temperatures will be 15 to 20 degrees below average over parts of Northern California/Pacific Northwest into parts of the Northern Rockies... High pressure over the Mid-Atlantic will slowly inch off the East Coast. Likewise, a front extending from the Upper Mississippi Valley to the Central Plains then roughly westward into the Great Basin will advance slowly eastward to the Upper Great Lakes to the Central Plains then into the Central Rockies and parts of the Great Basin by Thursday evening. Associated upper-level energy over the Northwest will move northeastward to South-Central Canada by Thursday. Additional upper-level energy will move onshore over the Pacific Northwest on Thursday morning moving to the Northern Intermountain Region by Thursday evening. The first batch of upper-level energy will produce showers and thunderstorms over parts of the Great Basin/Northern Intermountain Region to the Northern High Plains and the Central Rockies on Wednesday morning will expand into parts of the Upper Midwest by Wednesday evening. On Thursday, showers and thunderstorms will develop along and ahead of the front over the Upper Midwest during the morning and advance into parts of the Upper Great Lakes to the Middle Mississippi Valley by Thursday evening. The second bundle of energy will produce rain along portions of the Pacific Northwest/Northern California Coast that will expand into parts of the Northern Intermountain Region by Wednesday evening. On Thursday, the rain will move into the Northern Rockies with showers and thunderstorms developing over parts of the Central High Plains by Thursday evening. Additionally, onshore flow off the Pacific will produce rain along the Northwest Coast on Thursday. Meanwhile, onshore flow off the Gulf of Mexico will aid in producing showers and thunderstorms over parts of the Western Gulf Coast on Wednesday morning. In addition, upper-level energy over parts of the Southeast and flow off the Atlantic will produce showers and thunderstorms over the Eastern Gulf Coast and the Southeast Coast through Thursday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php