Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 131 AM EST Sat Feb 03 2018 Valid 12Z Sat Feb 03 2018 - 12Z Mon Feb 05 2018 ...Unsettled weather with locally heavy rain and snow will continue over the Pacific Northwest and the Northern Rockies... ...A new storm developing over the Midwest will bring a threat of snow to areas of the Great Lakes, Central Appalachians and Northeast by the end of the weekend... ...Arctic air will pour south across the Northern Plains and Upper Midwest... Moist onshore flow associated with a series of storm systems will keep much of the Pacific Northwest to the Northern Rockies in an unsettled, and wet pattern through the weekend and into early next week. This will bring locally heavy rain to coastal Washington while the higher elevations to the east will have heavy snow. Areas of the Washington Cascades, and especially the interior ranges of the Northern Rockies including the Bitterroots, Tetons and Big Horns will see as much as 2 to 3 feet of fresh snow through Monday. For the rest of the Western U.S., mild and dry conditions are expected to continue. Temperatures across the Southwest, Great Basin and California will generally be near or above average. Meanwhile, very cold air initially in place over portions of the Eastern U.S. will quickly erode as high pressure advancing over the Mid-Atlantic region today moves offshore the East Coast by Sunday. This will allow temperatures to begin to moderate as southerly winds begin to return. However, as this area of high pressure moves offshore, a complex storm system will be developing over the Central Plains and Middle Mississippi Valley as some of the energy impacting the Northwest U.S. drops southeast. Multiple waves of low pressure will impact the broader Midwest through the weekend which will allow for a swath of accumulating snow across the Great Lakes, Central Appalachians and the Northeast. It appears that temperatures should warm up just enough across the Mid-Atlantic region for generally a cold rain to fall here, but some snow initially along with pockets of freezing rain can be expected. More widespread and heavier rain is expected farther south from the Tennessee Valley to the Gulf Coast states and including interior areas of the Southeast as a separate area of low pressure impacts this region and draws a more substantial axis of moisture north in off the Gulf of Mexico. Another blast of arctic air will plunge south from Canada late this weekend and arrive over the much of the Northern U.S. In fact, over areas of the Northern Plains and Upper Midwest, daytime temperatures will struggle to get out of the single digits and nighttime lows will be well below zero. These temperatures coupled with the wind will result in dangerously cold windchill values. Some of this very cold air will settle southeast across portions of the Central and Eastern U.S. going into the early part of next week. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php