Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 254 AM EST Tue Jan 15 2019 Valid 12Z Tue Jan 15 2019 - 12Z Thu Jan 17 2019 ...Heavy precipitation returns to California and arctic air surges south across the northern plains... A very active weather pattern will be in place across California and then the Intermountain West through the middle of the work week. A deep Pacific trough off the West Coast will remain in place over the next few days with a frontal boundary approaching central California Tuesday evening, and a much stronger storm arrives Wednesday night. The result will be widespread rain with enhanced rainfall for the coastal mountain ranges, and WPC has a moderate risk of flash flooding across the mountainous terrain near Los Angeles for Tuesday. Heavy snow will fall across the Sierra Nevada and Siskiyou mountains of California, with amounts exceeding a foot at the highest elevations. Elsewhere across the continental U.S., a strong cold front drops southward across the Plains on Tuesday and into early Wednesday, bringing frigid temperatures to the Dakotas and the Upper Midwest by the middle part of the week. There should be enough moisture with this front to produce some mixed precipitation over the lower Great Lakes and snow showers behind the front over northern Michigan. With a large surface high over the Gulf Coast region, return flow from the Gulf of Mexico will begin to bring increasing moisture through eastern Texas and into the central Plains, where some showers are likely on Wednesday. In addition, the northern extent of the moisture could result in some wintry precipitation across the north-central Plains on Wednesday as well. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php