Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 402 AM EST Wed Dec 07 2016 Valid 12Z Wed Dec 07 2016 - 12Z Fri Dec 09 2016 ...Heavy snow possible over the Sierras... ...Heavy snow possible in downwind favored areas from the Great Lakes... ...Rain/freezing rain possible over interior portions of the Pacific Northwest/Northern California... ...Temperatures will be 15 to 35 degrees below average over the Northern/Central Rockies and High Plains... Deep low pressure just north of the Great Lakes will slowly move northeastward to just east of James Bay by Thursday evening. The energy will produce snow over parts of the Northern Plains to the Upper Great Lakes through Thursday with the snow ending over the Northern Plains and the Upper Mississippi Valley on Thursday afternoon into evening. The associated upper-level low will pass just north of the Keweenaw Peninsula on Wednesday that will aid in producing the heaviest snow over that region of the Great Lakes. The lake effect/enhanced snow will move into the Lower Great Lakes on Thursday morning into evening. In addition, a front extending from the Lower Great Lakes/Northern Appalachians southward to the Southeast will move eastward off the East Coast by Thursday morning. Higher elevation snow and rain will develop over parts of the Central Appalachians/Lower Great Lakes eastward to the Northeast/Northern Mid-Atlantic that will slowly wind down west to east overnight Wednesday. Meanwhile, upper-level energy over the Great Basin/Central Rockies will move eastward to the Northeast by Thursday evening. The energy will aid in producing snow over parts of the Great Basin into parts of the Central High Plains on Wednesday morning ending by Wednesday evening. Upper-level jet dynamics will aid in producing rain over parts of the Western Gulf Coast starting overnight Wednesday that will expand into the Lower Mississippi Valley and Southern Plains on Thursday retreating to the southern tip of Texas by Thursday evening. Furthermore, a boundary moving over Southern Florida will aid in producing showers and thunderstorms over the region Wednesday morning into Thursday evening. Elsewhere, a front over the Eastern Pacific will approach the West Coast Wednesday into Thursday. A plume of moisture associated with the system will begin to move onshore over California on late Wednesday morning, expanding into parts of the Pacific Northwest on overnight Wednesday into Thursday. Rain and higher elevation snow will develop over Central/Northern California by Wednesday evening. The snow will expand eastward into parts of the Great Basin/Northern Intermountain Region by Thursday evening. Rain and higher elevation snow will move into parts of the Pacific Northwest early Thursday morning expanding northward into Washington State on Thursday afternoon into evening. Additionally, rain and freezing rain will develop over interior parts of Northern California/Pacific Northwest on Thursday morning into evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php