Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 322 AM EST Tue Jan 28 2020 Valid 12Z Tue Jan 28 2020 - 12Z Fri Jan 31 2020 ...Pacific Northwest to the Northern Rockies... Days 1-3... The models show the likelihood of another round of 6-10 inches snow in the western WA/OR Cascades as a 700 mb wave from the eastern pacific moves towards the coast and onshore today, driving a surge of moisture and lift across WA/OR and then into the northern Rockies, where secondary maxima are expected in the ranges of ID/northeast OR to northwest WY. This system is expected to quickly move out of the northern Rockies region by Wednesday. However, an upstream ridge will quickly give way to another band of enhanced moisture and loft steadily progressing onshore in WA and then steadily progressing across ID and into western MT. Late Thu to Thu evening, the 00z ECMWF shows a following wave arriving centered near 00z Fri in western WA, accompanied by relative humidity of 90-100 percent and moderate ascent. An additional several inches of snow are projected for the northern WA Cascades. Due to the limited duration of a several hour period, odds are low for heavy snow chances, as there are multi-hours breaks of reduced relative humidity and lift in between waves of moisture/ascent. ...Southern and Central Plains... Day1... Models continue to show a closed 850 mb low tracking from the TX panhandle east southeast down the Red Rover Valley/adjacent southern OK. Cold air surging south on the backside of the system will support a change from rain to snow from southwest Kansas across the OK/TX panhandles, and Northwest Oklahoma. Models continue to present a signal for several inches centered over southwestern Kansas and northwestern Oklahoma. However, confidence in the details remains limited in part due to uncertainties from the changeover timing and duration of snowfall. Probabilities for accumulations of 4-inches or more peak over southwestern Kansas into northwestern Oklahoma, including the eastern Panhandle. Low probabilities for 8 inches exist as the high res windows show locally higher QPF in the form of snow near 0.75 inches. As the low weakens progressing into AR, snowfall rates taper in southeast KS to southern MO, where only light amounts are expected. Light freezing rain is possible in the precip type transition zone across southeastern KS, which follows continuity from freezing rain obs in southwest KS the past few hours. The probability of 0.25 inches of freezing rain is less than 10 percent Days 1-3. Petersen