Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 303 AM EST Wed Dec 18 2019 Valid 12Z Wed Dec 18 2019 - 12Z Fri Dec 20 2019 ...Relatively quiet weather pattern for much of the U.S. but the Pacific Northwest will soon enter an extended period of precipitation... ...Arctic air expected to surge across the Northern Plains toward New England, while mild temperatures spread eastward from the lee of the northern and central Rockies... An intensifying low pressure system continues to quickly move away from the eastern U.S., bringing an end to the rain and thunderstorms along the East Coast, and the snow to taper off this morning across New England. However, as an arctic cold front approaches from the Great Lakes, snow and snow showers are expected to spread from west to east across New England later today into tonight. The cold front will then usher arctic air into the region under blusterly west to northwest winds. Temperatures are forecast to dip into the single digits by Thursday morning across interior New England with below zero readings forecast near the Canadian border. Farther west, the arctic air has already dropped temperatures to well below zero this morning over the upper Midwest. As the frigid air flow across the warm waters of the Great Lakes, lake-effect snow is expected to be very active today with some snow squalls likely bringing locally heavy amounts. Over the northern and central Plains, downslope/Chinook winds blowing down the lee of the Rockies will result in milder than normal temperatures through the next few days. Along the West Coast, a compact low pressure system is expected to spread rain into central and northern California today with snow over the higher elevations. Farther north, a Pacific front will spread precipitation into the Pacific Northwest today. With large-scale Pacific fronts and cyclones continue to aim for the Pacific Northwest, an extended period of precipitation is anticipated for the region as we head toward the end of the week. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php