Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 341 PM EST Mon Dec 19 2016 Valid 00Z Tue Dec 20 2016 - 00Z Thu Dec 22 2016 ...Heavy rain for parts of the Pacific Northwest... ...Heavy snow for the Cascades... ...Snow from parts of the Northern Plains to the Upper Great Lakes... ...Rain/Freezing rain possible for parts of the Northern Intermountain Region... A front moving onshore over the Pacific Northwest will move to the Northern/Central Plains by Wednesday. Onshore flow ahead of the front will aid in producing rain and higher elevation snow over parts of the Pacific Northwest with snow over parts of the Northern Intermountain Region/Northern Rockies through Tuesday morning. When the boundary moves onshore, rain and higher elevation snow will continue over the Northwest. The snow levels will lower when the front passes over the area then the rain and snow will end overnight Tuesday. As the front moves into the Northern Intermountain Region/Northern Rockies, pockets of rain/freezing rain will develop over parts of the Northern Intermountain Region on Tuesday morning. Other places over the Northern Intermountain Region/Northern Rockies, snow will continue on Tuesday and begin to wane by Wednesday morning. Overnight Tuesday, snow will develop over parts of the Northern High Plains into the Northern Plains by Wednesday morning. Meanwhile, upper-level energy over the Northern High Plains will move eastward to the Great Lakes by Tuesday afternoon and into the Northeast by Wednesday morning. The system will produce snow over parts of the Northern Plains into the Upper Mississippi Valley that will move into the Upper Great Lakes on Tuesday ending by Wednesday morning. Snow will develop in places over the Northern Appalachian into Northern New England Tuesday evening into Wednesday morning. Elsewhere, a wave of low pressure just off the Eastern Florida Coast will move out over the Atlantic as the associated front moves from Central Florida to the southern tip of Florida by Wednesday. The system will produce rain and thunderstorms over parts of the Southeast Coast moving off the coast by Tuesday evening. Showers and thunderstorms will retreat to the southern tip of Florida by Wednesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php