Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 244 PM EST Mon Feb 04 2019 Valid 00Z Tue Feb 05 2019 - 00Z Thu Feb 07 2019 ...Heavy rain and threats for flash flooding continue for portions of California tonight... ...Heavy snow likely over mountainous regions from the Sierras to the Central Rockies... ...Wintry mix expected for portions of the Midwest and Great Lakes Tuesday evening through Wednesday afternoon... ...Temperatures will be well below average from Montana into the Dakotas and well above average from the Southern Plains to the East Coast... A highly active pattern will continue across the lower 48 early this week with a series of storm systems impacting locations west of the Continental Divide bringing snow for the mountains and lower elevations of the Intermountain West along with lower elevation rain. Heavy rain with the potential for flash flooding will continue to be a concern through early tonight across recent burn scar locations of northern California along with the Transverse Ranges of southern California. While rainfall intensities may not be as high across southern California as in recent days, much of the area has received 200 to 400 percent of their normal precipitation over the past seven days which has left portions of the area susceptible to runoff due to heavy rain. As a pair of cold fronts move across the western U.S. over the next two days, snow levels will fall allowing temperatures to support snow across lower elevations of northern California and much of Oregon as well as much of the Intermountain West by Tuesday afternoon. Snow will be measured in feet across the Sierra Nevada Mountains and portions of the Wasatch Range, with locally heavy snow also expected into the central to northern Rocky Mountains. Due to the magnitude of cold air expected across the Intermountain West, many lower elevation locations will see at least light snow over the next two days. Arctic air will stay entrenched across the Northern Plains into much of Montana through the middle of the week with temperatures ranging 20 to 40 degrees below average. Sub-freezing temperatures will also extend into northern portions of the upper Great Lakes region. Ahead of a surface low/cold front tracking through the Great Lakes, total accumulations of a quarter to a half inch of freezing rain are expected by this evening from northern Wisconsin into the U.P. of Michigan. Colder temperatures will filter in behind the cold front supporting a threat for a wintry mix of snow for the Upper Mississippi Valley and freezing rain for portions of the Midwest and lower Great Lakes late Tuesday into Wednesday, with all rain closer to the Ohio Valley. Ice accumulations between 0.10-0.20" are expected across portions of the lower Great Lakes including Chicago and Quad Cities, IL metro areas. Potential exists for significant freezing rain and ice accumulations (0.25") across southern Michigan, including the Detroit metro area. By Wednesday, another wave of low pressure will eject into the Southern Plains underneath the strong arctic high in southern Canada. This will lead to an area of snow across the northern and central Plains, as well as parts of the Upper Midwest by late Wednesday. Meanwhile, heavy rain will be possible along a stationary front in the Ohio and Tennessee valleys. Snell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php