Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 319 AM EST Tue Dec 15 2015 Valid 12Z Tue Dec 15 2015 - 12Z Thu Dec 17 2015 ...Heavy rain possible over parts of the Northwest Coast... ...Heave rain possible over parts of the Southern Appalachians... ...Snow possible from parts of the Central/Northern Plain into the Upper Mississippi Valley and parts of Northern Maine... A storm over the Central High Plains will move northeastward to the Upper Mississippi Valley/Upper Great Lakes by Wednesday evening. The system will produce snow over parts of the Central/Northern Rockies and parts of the Central/Northern High Plains that will move into the Northern/Central Plains by Tuesday evening and into parts of the Upper Mississippi Valley/Upper Great Lakes by Wednesday. Moisture from the Gulf of Mexico will begin to pool along the associated front by Tuesday afternoon producing rain over parts of the Southern Plains/Lower Mississippi Valley. Rain will also develop over parts of the Middle Mississippi Valley by Tuesday evening. The area of rain will expand southward from the Middle Mississippi Valley and northward from the Lower Mississippi Valley to cover from the Upper Mississippi Valley/Upper Great Lakes to the Lower Mississippi Valley and parts of the Western/Central Gulf Coast by Wednesday morning. By Wednesday evening the rain will move eastward to the Great Lakes to the Central Gulf Coast/Southeast. Meanwhile, upper-level impulses moving onshore from the Pacific and a stronger area of upper-level energy moving southward from Western Canada will move over the Pacific Northwest into parts of the Northern Rockies from Tuesday evening into Wednesday. Onshore flow will also start over the Northwest Coast Tuesday afternoon. The combination of moisture and energy will aid in produce rain along the Pacific Northwest Coast into parts of Northern California with snow at the higher elevations of the Northwest and over parts of the Northern Intermountain Region/Northern Rockies Tuesday afternoon into Wednesday. Elsewhere, deep low pressure over the Northeast will move eastward out over the Western Atlantic by Wednesday morning. The storm will produce light rain over parts of the Lower Great Lakes and the Northeast on Tuesday morning. Snow will develop over parts of Northern Maine by Tuesday afternoon with the rain and snow ending by Tuesday night. The associated front will linger over parts of Florida before returning northward to off the Carolina Coast by Wednesday evening. The boundary and easterly flow off the Atlantic will aid in producing scattered light rain over parts of Florida through Wednesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php