Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 445 AM EDT Sat Nov 01 2014 Valid 12Z Sat Nov 01 2014 - 12Z Mon Nov 03 2014 ...Moderate to heavy snow expected for Maine and parts of the Northern Rockies this weekend... ...Much below normal temperatures anticipated across the Eastern third of the nation... A highly amplified flow regime will predominate across the CONUS as we enter the month of November. A powerful closed low diving rapidly across the Southeastern U.S. will bring an early taste of winter to the southern Applachians as strong dynamic cooling results in accumulating snow across higher elevations Saturday. Amounts will be relatively limited due to the rapid movement of the system. This feature will move offshore later Saturday and induce surface cyclogenesis off the Carolina coast, which will strengthen as it moves up the Eastern seaboard. As a result, much of the East Coast will experience very cool, breezy and unsettled weather through the weekend. The most significant precipitation after early Saturday morning is expected over the Northeast, with one area of overrunning precipitation pushing in by Saturday afternoon. This should start out as mostly rain, but cold air advection from Eastern Canada will allow precipitation to change to snow Saturday night across all but coastal sections of Maine. There will be a relative lull in the precipitation late Saturday night, but as the coastal low strengthens and moves northward into Nova Scotia Sunday, a second round of heavy precipitation...all snow...will sweep across Maine. Snowfall amounts of over a foot are possible over east-central sections of the state. Meanwhile, high pressure settling in behind this low will bring widespread freezing and sub-freezing overnight low temperatures to large areas of Missouri/Tennessee Valleys and into the Deep South Saturday and Sunday mornings. In the West, a highly amplified trough moving onshore is bringing welcome precipitation in the form of valley rains and mountain snows to drought-stricken areas of California. This system will push steadily eastward through the Great Basin and Rockies during the next two days, with one piece of upper energy shearing into the Northern Rockies, while the remainder hangs back across the Southwest. The bulk of the dynamics and Pacific moisture are associated with the northern wave, which will likely bring heavy snow accumulations into the mountains of central Idaho and western Montana this weekend. The southern end of the trough will tap into some tropical moisture, which should help fuel convection across Arizona and New Mexico on Sunday. Late in the period, increasing onshore flow associated with a series of weak upper impulses embedded in the westerlies will bring and renewed chance for light precipitation into the Pacific Northwest late Sunday into Monday. Elsewhere...ridging in the Central States will support mostly dry and very mild conditions, though winds across the Plains will be on the increase Sunday as southwesterly flow strengthens in advance of the Pacific trough sliding across the Rockies. Klein Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php