Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EST Mon Nov 27 2017 Valid 12Z Mon Nov 27 2017 - 12Z Wed Nov 29 2017 ...Heavy rain and snow for the Sierras... ...Heavy rain possible over the Pacific Northwest Coast and Heavy snow for the Cascades... ...Snow for areas downwind of Lake Ontario... ...Temperatures will be 20 to 30 degrees above average for Central/Northern Plains and parts of the Southern High Plains... A low pressure system and associated surface cold front will pass through exit the Rockies and move east through the Northern and Centrals Plains today- with the leading edge passing through the Great Lakes and the Northeast by Wednesday morning while the southern edge sinks southward and stalls over the Central and Southern Plains. Prior to the frontal, temperatures today across the south-central U.S. will be well above average. As the front moves further inland across the Pacific Northwest the snow levels will lower from the coast to the Intermountain West. Heavy snow is expected over the Cascades early this morning before decreasing intensity this afternoon and evening-- with snow accumulations increasing for portions of the Northern Rockies by Tuesday. Also, the rain over the coastal areas of Pacific Northwest will increase in coverage by expanding south into parts of Northern/Central California. There will be periods of heavy rain and snow will also develop over the Sierras. A weak front moving through the Lower Great Lakes and Northeast today will produce light snow over parts of the Lower Great Lakes into the Northern Appalachians. Counties east of Lake Ontario will have some lake enhancement of the snow today. A Winter Weather Advisory and Lakeshore Flood Warning is in effect. Elsewhere, upper-level energy will move over the southern tip of Florida this afternoon and into Tuesday; which will aid in producing showers and thunderstorms over the southern tip of Florida. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php