Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 301 AM EST Tue Dec 10 2019 Valid 12Z Tue Dec 10 2019 - 12Z Thu Dec 12 2019 ...Rain changing over to snow during the early morning on Wednesday a long the I-95 corridor... ...Heavy lake effect snow along parts of Lake Superior Coastline... ...Wind chill advisory in effect over parts of the Upper Midwest on Tuesday morning... Temperatures will be 10 to 20 degrees above average over parts of the East Coast in contrast, temperatures will be 10 to 25 degrees below average over parts of the Upper Midwest... A front extending from the Lower Great Lakes southwestward to the Central Gulf Coast will move eastward off the East Coast and Gulf Coast by Wednesday. The boundary will produce rain from parts of the Northeast across the Central Appalachians into parts of the Central/Western Gulf Coast moving off the Northeast Coast by Wednesday evening and the Gulf Coast by Wednesday afternoon. The rain will change over to snow over parts of the Southern Plains and the Lower Mississippi/Southwestern Ohio/Western Tennessee Valleys by Tuesday morning. Likewise on the back edge of the precipitation shield, rain will change over to snow over parts of the Northern/Central Appalachians into parts of the Lower Mississippi Valley by Tuesday afternoon. As the front continues to move eastward, rain changing to snow will move into the I-95 corridor during the early morning to late morning on Wednesday producing hazardous traveling conditions for the morning rush hour. The rain and snow slowly end over the Lower Mississippi Valley and Ohio/Tennessee Valleys overnight Tuesday. The snow over the Northeast to the Mid-Atlantic will end by Wednesday evening. Furthermore, lake effect and lake enhanced snow will develop over the Upper Great Lakes through Wednesday evening. Another front extending from the Middle Mississippi Valley roughly northwestward to the Northern Rockies will remain quasi-stationary through Thursday morning. The boundary will aid in producing scattered snow over parts of the Northern Rockies/Northern High Plains through Wednesday morning. Meanwhile, upper-level energy will move onshore over the West Coast on Tuesday evening and moves inland to the Plains by Thursday morning. The energy will aid in producing rain over parts of the Pacific Northwest/Northern California Coast on Tuesday. As the energy and associated moisture will move inland producing higher elevation snow over parts of the Northwest and Northern California overnight Tuesday. On Wednesday, snow develops over parts of the Northern Intermountain Region into the Great Basin. The snow will become more scattered The main feature of interest for the beginning to middle part of the week will be a strong cold front crossing the eastern U.S. and Gulf Coast region. Widespread rain is expected ahead of the front Monday night and into Tuesday with temperatures briefly above average on Tuesday for the East Coast. The front will herald the arrival of an arctic airmass to much of the Great Lakes region and eventually to the Mid-Atlantic and Northeast by midweek. There will likely be enough moisture and upper level forcing in place behind the front to support a transition to snow from the central Appalachians to New England before ending on Wednesday. The western U.S. initially begins on a tranquil note through most of Tuesday before a more unsettled weather pattern arrives. A weakening front from the eastern Pacific will generally support some light showers and mountain snow, followed by another round of precipitation by Wednesday as a stronger storm lurks offshore. The heaviest precipitation should be across southern Oregon and northern California. Elsewhere across the continental U.S., dry conditions can be expected from the Desert Southwest to the Upper Midwest. It will continue to be bitterly cold from eastern Montana to northern Michigan with widespread subzero lows and single digit highs. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php