Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Mon Jan 21 2019 Valid 12Z Mon Jan 21 2019 - 12Z Wed Jan 23 2019 ...Very cold and blustery conditions in the eastern U.S. will moderate by Wednesday... ...Developing low pressure system currently bringing heavy snow over the Rockies will become the next winter storm for northern Plains to the Great Lakes... ...Active weather returns for the Pacific Northwest into the Intermountain region... A broad and energetic upper-level trough is currently moving across northern California where rain has been widespread. This system is expected to penetrate further inland and develop into a large low pressure system as it moves across the Rockies today, bringing widespread mountain snow from the Great Basin eastward into much of the northern and central Rockies. The system will then exit the Rockies tonight and become the next winter storm for the northern Plains and expanding into the Great Lakes on Tuesday. Up to 8 inches of snow can be expected over the upper Midwest on Tuesday. By Wednesday morning, the wintry precipitation should reach New England, with freezing rain possible over the northern and central Appalachians. The storm will also tap into mild and moist air from the Gulf of Mexico. Rain is expected to expand across the lower and mid-Mississippi Valley on Tuesday near a warm front and ahead of a strong cold front. Some thunderstorms will be possible over the eastern Gulf states by Wednesday morning. In the eastern U.S., frigid air from Canada will pour into the area in the wake of the major winter storm. High temperatures today will be more than 20 degrees below normal across much of the Northeast. The flow of frigid air over the Great Lakes will promote lake-effect snow as well as upslope snowfall over parts of the central Appalachians through this evening. Temperatures will begin to moderate on Tuesday as the arctic high pressure system slides off the East Coast. Meanwhile, more active weather is forecast to reach the Pacific Northwest on Tuesday ahead of the next energetic Pacific cyclone. Expect coastal heavy rain and windy conditions to resume on Tuesday with snow spreading rapidly eastward into the Intermountain region Tuesday night, reaching the northern Rockies early on Wednesday, and into the northern High Plains Wednesday morning. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php