Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 320 PM EST Mon Jan 09 2017 Valid 00Z Tue Jan 10 2017 - 00Z Thu Jan 12 2017 ...Relentless rain and snow over much of the western U.S. will be reinvigorated by another powerful storm moving onshore late Tuesday... ...A winter storm is forecast for the upper Midwest and Great Lakes on Tuesday... ...Mild temperatures expected for much of the central and eastern U.S. as next surge of arctic air reaches the northern Rockies... The western U.S. will once again be the target of more heavy rains and snows. The second in a series powerful low pressure systems currently located north of Hawaii is forecast to move rapidly eastward and reach the western U.S. late on Tuesday. Widespread rain and snow, heavy at times, currently over much of the West will once again intensify from west to east late on Tuesday into Wednesday. The northern half of California will be first in line for heavy rain to arrive during the day on Tuesday along with increasing winds, especially near the coast and on higher grounds. The intensity of the storm should culminate Tuesday night with a threat of flash flooding and a chance of thunderstorms near the coast, and heavy snow in the Sierras. The precipitation will once again penetrate rapid inland across much of the Great Basin, Intermountain region, and much of the northern and central Rockies through Wednesday evening. Some of the lower elevations will see mixed precipitation and freezing rain. The strong and energetic upper-level jet stream will continue to carry moisture-laden air eastward into the northern Plains on Tuesday. As the jet stream interacts with a reinforcing surge of arctic from Canada, a low pressure system is forecast to form and intensify rapidly as it moves across the northern Plains during the day on Tuesday and into the Great Lakes by Tuesday evening. This will bring a period of snow with strong gusty winds across the upper Midwest into the upper Great Lakes on Tuesday. Showers and thunderstorms will be possible farther south across the Ohio and Mississippi Valleys ahead of a cold front late on Tuesday as well. Meanwhile, snow across the northeastern U.S. is forecast to change over to mixed precipitations and all rain from west to east on Tuesday, as mild air works it way in from the southwest. Arctic air currently in the Eastern Seaboard will give way to milder temperatures as a large area of warm air forecast to develop in the central U.S. moves eastward. High temperatures are forecast to be 20 to 30 degrees above average on Wednesday afternoon in the central U.S. as the next surge of arctic air filters into the northern Rockies, where temperatures are expected to drop to more than 20 degrees below normal. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php