Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 327 AM EST Thu Dec 19 2019 Valid 12Z Thu Dec 19 2019 - 12Z Sat Dec 21 2019 ...A long duration precipitation event beginning to impact the Pacific Northwest... ...Chance of rain increasing toward the weekend for the Gulf states... ...Arctic air over the eastern U.S. will slowly moderate while mild temperatures expand across the Plains and into the northwestern U.S.... A long duration precipitation event is in store for the Pacific Northwest as an active stream of moisture is forecast to aim toward the region for the next few days. This pattern is sustained by an active jet stream pivoting around a large-scale cyclone which is forecast to remain stationary over the northeast Pacific, spawning multiple waves of low pressure toward the Pacific Northwest. Long periods of moderate to heavy rain could result in rainfall amounts locally exceeding 10 inches over western Washington and Oregon through Saturday morning. Over the higher elevations in the interior sections, heavy wet snow is forecast to accumulate between 1-3 feet with locally higher amounts by Saturday evening. After a day of active snow showers and snow squalls across many locations in New England, the activities should gradually subside today as the arctic cold front behind a deep storm moves farther away. Much of New England will remain in the deep freeze as we head into the weekend. In contrast, warmer than normal temperatures across the northern and central Plains are expected to expand eastward into the Great Lakes, Ohio Valley and the Southeast by the weekend. Much of the Pacific Northwest will be 5 to 15 degrees warmer than normal as well as the heavy rain and mountain snow continue. Over in central California, rain associated with a low pressure system is tapering off as it continues to move farther inland into the Great Basin. By Friday, the closed upper level low associated with this system is forecast to reach Texas. This will begin to pull in moisture from the Gulf and increase the chance of rain for the Gulf states from west to east toward the weekend. This system will need to be watched closely as the vigorous dynamics appear to support the development of a significant storm system further into the weekend. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php