Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 332 AM EST Mon Dec 02 2013 Valid 12Z Mon Dec 02 2013 - 12Z Wed Dec 04 2013 ...Heavy snow will be possible across the higher terrain of the West along with the Northern Plains/Upper Midwest... ...Well below normal temperatures should be commonplace across the West... A fairly busy start to the first few days of meteorological winter which commenced December 1st. The current National Weather Service hazards paints this picture quite well with a myriad of winter storm watches/warnings/advisories in place over much of the West and North-Central U.S. A potent upper low currently crossing Vancouver Island is forecast to continue dropping southward into the Pacific Northwest. This system will help draw arctic air south of the U.S./Canadian border which should bring quite the chill to the air early this week. Strong vertical lift in response to the upper low will bring widespread precipitation to much of the western states with topography aiding in additional lift through orographic effects. The modestly high snow levels to begin the event will quickly come down as the arctic air mass infiltrates the region. It appears wintry precipitation will be possible into the valley locales of the Intermountain West although the heftiest accumulations are forecast to remain in the higher terrain. During the next couple of days, the WPC winter weather desk suggests 12 to 18 inches of snow will be possible over the Tetons, Wasatch, and Colorado Rockies. As the aforementioned upper low drops down from Vancouver Island into the Pacific Northwest, forecast models suggest the disturbance will split into two. One of these impulses will be responsible for the unsettled conditions over the Western U.S. while the other should shift eastward toward the Northern Plains. The latter location is forecast to have better access to low-level moisture as the Gulf of Mexico brings sufficient return flow to the Central U.S. Temperatures are expected to be plenty supportive for snow as the dominant precipitation type with over a foot possible across much of Northern Minnesota. The arctic intrusion will bring very chilly temperatures to the Western/Central U.S. Although the air mass will modify in time, readings will remain well below normal with highs by Wednesday only in the lower single digits across the Upper Intermountain West, Northern Rockies, and sections of the Northern Plains. Lows will easily plunge into the negative teens in the some of the coldest locations. Meanwhile, even the lower valley locations across the Central Great Basin can expect highs in the 20s. The only other major system affecting the map is a coastal storm which should be just far enough off the coast to only produce limited effects. The area which could be grazed by the cyclone is coastal Maine with heavier precipitation falling in close proximity to the mainland. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php