Extended Forecast Discussion NWS Weather Prediction Center College Park MD 126 AM EST Sat Feb 02 2019 Valid 12Z Tue Feb 05 2019 - 12Z Sat Feb 09 2019 ...Overview... Active weather week next week as a Pacific system on Tuesday will push toward the central Plains and then lift into the Great Lakes/Northeast Friday. High pressure will settle down from Canada with very cold temperatures for the High Plains behind an arctic front but rather mild temperatures in the east. ...Guidance/Predictability Assessment... Consensus among the recent 18Z/12Z GFS and 12Z ECMWF offered a reasonable starting point with the pair of systems on Tuesday and continuing into Thursday as the closed upper low moves inland over northern California. This will carry a front underneath the arctic airmass to the north (stumbling over the Divide) through the Rockies and onto the southern Plains early Thursday. For next Fri/Sat, the models/ensembles have really struggled with both the upstream Pacific evolution (offshore OR/CA as well as across western Canada) and the track of the surface low (and possible lingering surface waves in the lower MS Valley) out the St. Lawrence Valley. Considerable spread exists in the precipitation forecast next Fri/Sat (rain and northern side snow) but favored the drier ECMWF ensemble guidance given a favored progressive front into the Gulf and Atlantic. ...Weather Highlights/Hazards... Temperatures will be much below average (20-40 degrees negative anomalies) over Montana into the High Plains for much of next week behind the arctic front. The east/Southeast will see a lead surge of much milder temperatures ahead of the lead cold front Tue/Wed that will again rise Fri/Sat until that front pushes off the coast. Some record highs may be possible from the deep South into the Northeast. Initial western storm will finally exit on Tuesday into Wednesday after a very stormy period. Rain will expand east of the Plains Thursday as the low lifts into the Lakes with some snow on the north side. Lake effect snow will attempt to re-establish itself with limited cold air but may resume in earnest by next weekend as Canadian high pressure pushes through the Upper Midwest with NW to W flow across the Lakes. Fracasso WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation and winter weather outlook probabilities are found at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4