Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 417 PM EDT Wed Apr 04 2018 Valid 00Z Thu Apr 05 2018 - 00Z Sat Apr 07 2018 ...An unusually cold surge of arctic air will drop temperatures into record low territories from the Plains eastward into the Midwest... ...Snow will develop in the northern Rockies and spread towards the central Plains during the next couple of days... A highly blocky synoptic pattern in the high latitudes is setting the stage for an unusually cold surge of arctic air for April to usher into the U.S. First of all, a strong low pressure system that has brought showers and thunderstorms along the East Coast and wintry precipitation over northern New England today should continue to move quickly off to the east through tonight. Cold air behind the storm will overspread the eastern U.S. with blustery west to northwest winds. Areas downwind of the lower Great Lakes will see the highest chance of lake-effect snow through Thursday morning. Meanwhile, a colder surge of arctic air with an associated arctic high pressure system is building in western Canada. Snow is expected to develop and expand along an arctic front across the northern Rockies. The snow will then spread eastward across the northern High Plains and into the central Plains on Friday. By Friday evening, energy will be focused along a strong arctic cold front as a low pressure center begins to form in the central Plains and move toward the mid-Mississippi Valley. Moderate snow and a narrow band of freezing rain are expected to the north of the storm center while thunderstorms are possible to the south. Meanwhile, the northern Plains into the Midwest will be in the deep freeze as the core of the arctic air sends temperatures down into the single digits, which are more than 30 degrees below normal for some areas. Meanwhile, active weather will continue across the Pacific Northwest and Intermountain West as an influx of moisture will first bring coastal showers and mountain snow into the Pacific Northwest. By Thursday, an impressive flux of moisture ahead of a frontal system will bring the next round of precipitation, this time extending southward into northern California. By Friday, the coverage and intensity of the rain are expected to increase through much of northern and central California as a warm front ahead of the next Pacific storm approaches the West coast. The Desert Southwest and the southern Rockies will remain dry. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php