Extended Forecast Discussion NWS Weather Prediction Center College Park MD 145 AM EST Mon Feb 04 2019 Valid 12Z Thu Feb 07 2019 - 12Z Mon Feb 11 2019 ...Overview... Upper ridging will dominate the area just west of the Gulf of Alaska as well as across the Florida Straits. This will favor renewed troughing along the West Coast with a storm track northeastward through the Great Lakes/St. Lawrence Valley. ...Guidance/Predictability Assessment and Preferences... 12Z GFS/ECMWF and their ensembles have finally come much closer together in the Thu/Fri period with respect to the Northeastern Pacific separation and the speed of ejection of the Four Corners trough. The ECMWF ensembles have been the leader in this flow pattern but the GFS/GEFS were much more in line so that a blended solution offered a good starting point. This will take a lead system out through southern Ontario Friday as another trough drops down the West Coast. Canadian high pressure will slide southeastward this weekend into the Mid-Atlantic as a weak system attempts to lift into the Lakes next Sun/Mon. To the south, the upper ridge will keep the surface front from sinking much past central Florida and then return through the Gulf Coast as a warm front late in the period. Weather Highlights/Hazards... Well above average temperatures in the Southeast/East (with record highs possible) Thursday will be replaced by nearer to then below average temperatures (especially north of ~I-70) as the cold front clears the East Coast. From MT to the Upper Midwest temperatures will remain well below average on the north side of an arctic front that will linger near the Divide. The rest of the West will mostly see below average temperatures due to the persistent troughing. A swath of heavier precipitation (mostly rain but perhaps northern fringe snow) will spread east of the Plains through the OH/TN Valleys and into the northern Mid-Atlantic/Northeast on Thursday. Frontal/warm-sector rains may be locally heavy on Thursday but trend lighter on Friday as the system weakens and looses support. As the main low pulls away, lake-effect snow will resume at least Friday into Saturday ahead of the surface high. More precipitation will spread out of the Plains into the mid-MS Valley via another weak impulse out of the Rockies and to the north of the Gulf warm front. 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