Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 348 AM EST Wed Feb 12 2020 Valid 12Z Wed Feb 12 2020 - 12Z Sat Feb 15 2020 ...Central Plains across Midwest and the Northeast... Days 1 and 2... A southern stream trough ejecting from the southern Rockies early this morning will race northeast on an intensifying jet, crossing the Midwest tonight. This is just ahead of a northern stream trough pushing southeast across the Great Lakes through tonight. The surface low with this southern stream trough will develop around Houston this morning and race northeast across the TN Valley and central Appalachians tonight before crossing southern New England Thursday morning. The north side of an expansive precip shield will continue to be cold enough for snow with banding aided by the right entrance region of the intensifying jet streak and PVA ahead of the mid-level trough axis in a stripe from southwest KS this morning to northern MO/southern IA this afternoon, to the south side of Lake Erie this evening and central NY overnight and interior southern New England Thursday morning. A strip of wintry mix is expected along and ahead of the low track with areas of light icing (generally less than a tenth inch) from the StL metro to PA and southern NY interior southern New England. Furthermore, the strong cold front associated with the northern stream trough will cross Lake Superior early this afternoon and cross the eastern Great Lakes Thursday morning. This will set up lake enhanced and effect snow on a rather north/northeasterly flow. A meager 12 percent ice coverage over the entirety of the Great Lakes (essentially only bays are frozen) means there is plenty of potential energy for some greater than normal for this time of year lake effect snows that will continue through Friday. The Day 1 snow probability for four or more inches is moderate from southeast KS across north-central portions of MO and IL into northwest IN. The Day 1.5 snow probabilities include some LES with more moderate probabilities for four or more inches from northwest IN across the southern shore of Lake Erie and for higher elevations of Upstate NY and the mountains of New England and eastern Maine. Day 1 freezing rain probabilities for a tenth inch or more of ice are across central OH, northern PA, southern NY and the Berkshires of MA with some 20 to 30 percent probabilities for a quarter inch or more over the Catskills and Berkshires. ...Wyoming and Colorado... Day 1... A cold front banking up against the Front Ranges of WY and CO with strong high pressure building in from the Canadian Prairies as well as a northern stream shortwave riding along the front over the northern High Plains will produce fluffy snow over the eastern mountains of these states including the Big Horn and Laramie in WY and the Front Range and Sangre de Christos in CO to the NM border. Moderate snow probabilities for six or more inches are over the highest portions of these mountains. ...Pacific Northwest/Northern Rockies... Days 2-3... A trough pushes into western WA late Thursday, tracking to the ID/MT border by Friday morning and pushing across the Northern Plains by Friday night. Ample Pacific moisture ahead of this trough along with low snow levels (generally 2000 to 3000ft through the event) will make for heavy mountain snows. The Day 2.5 snow probabilities capture the event best with moderate to high probabilities for six or more inches over the Olympics, WA and northern OR Cascades, the Blue Mountains, and the northern ID/western MT ranges (as well as the Tetons in WY). Moderate probabilities for a foot or more are in place on Day 2.5 over the higher WA Cascades. Jackson