Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 AM EDT Thu Mar 15 2018 Valid 12Z Thu Mar 15 2018 - 12Z Sat Mar 17 2018 ...Up to a few feet of snow expected to fall over the Sierra Nevada ranges... ...A winter storm should affect the northern high Plains into large sections of South Dakota and Nebraska... ...An elevated to critical risk for wildfires exists from the southern Rockies eastward into the southern/central Plains... The initial setup across the country will feature an omega block with a ridge over the center of the country while closed lows are positioned to either side. Ultimately, this particular regime will maintain colder than average readings over most locations outside of the middle of the nation. In particular, expect temperatures around 10 to 15 degrees below climatology across the West as well as over the northern-central to northeastern United States. A well defined west-east oriented stationary front will be the boundary separating highs in the 70s and 80s over the southern Plains while 30s and 40s prevail to the north. Generally speaking, expect highs around 15 to 20 degrees above average over Kansas and Oklahoma. With the deep upper trough in place across West Coast, multiple embedded impulses will be foci for persistent, organized precipitation. While wet weather is anticipated over a vast majority of the western states, the best focus should be across the higher terrain over northern California into southwestern Oregon. This is where some of the stronger lift with the upper trough will combine with favorable orographics. More specifically, expect several inches of precipitation over the Sierra Nevada ranges, primarily snow given such cold temperatures aloft. At this point, 2 to 3 foot snowfall accumulations appear likely with isolated locations approaching 4 feet. While neighboring ranges will see lighter amounts, widespread amounts around 12 to 18 inches are possible over the Shasta, Siskiyou, Trinity, and Klamath ranges. As the upper trough across the western states advances inland, one particular disturbance is forecast to intensify over the central high Plains on Thursday evening. Strong lift underneath this system will combine with favorably easterly upslope flow to produce heavy snowfall anywhere from southeastern Montana and northeastern Wyoming into vast sections of western South Dakota and northwestern Nebraska. Amounts over a foot are likely across the Black Hills based on the latest forecast. An additional threat will be icing as mild air emanating from the Gulf of Mexico overrides a sub-freezing surface layer. This will be confined to locations north of the stalled surface front stretching from the central Plains into the Tennessee valley. This places significant icing potential anywhere from along and north of I-70 across Nebraska and South Dakota into a large chunk of the middle Mississippi valley. Given the intensification process occurring over the central Plains late Thursday, a strengthening pressure gradient will unfold at the surface. Dry gusty winds are likely across the southern Rockies eastward into the southern/central Plains which will enhance the risk for wildfires. Additionally, the U.S. Drought Monitor shows this area has a large rainfall deficit which will make this region more susceptible to a fire danger. The Storm Prediction Center fire weather outlook places an elevated to critical risk throughout the forecast period. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php