Extended Forecast Discussion NWS Weather Prediction Center College Park MD 130 AM EST Tue Nov 12 2019 Valid 12Z Fri Nov 15 2019 - 12Z Tue Nov 19 2019 ...Pattern Overview and Guidance/Predictability Assessment... Upper ridging on either side of North America will favor troughing over the CONUS with several embedded features. In the east, three longitudinally-aligned shortwaves will progress through southern Canada, the lower MS Valley, and the northeast Gulf on Friday. The former will swing sharply through the Northeast with a quick shot of reinforcing cold air while the latter will sneak out ahead of the middle feature into the Atlantic. The shortwave initially over MS Fri will likely slow down as heights build ahead of it and to the north. Low pressure is forecast to develop just off the Southeast coast and move northeastward. Western trough on Friday will help to move the eastern system along as the flow across the North Pacific remains progressive. The models/ensembles were mostly in agreement though the GEFS (and GFS) have seen a slowing trend toward the more steadfast ECMWF ensemble mean. Blend of the 12Z GFS/ECMWF served fairly well with the near-offshore eastern CONUS system (Canadian offshore, 18Z GFS along the Mid-Atlantic/New England coast). In the West, one upper low is still forecast to split off west of Baja California and remain offshore (18Z GFS not preferred) while to the north, ECMWF appeared too aggressive by next Tue. Blend with the 12Z GFS and ensembles tempered this area towards Great Basin troughing given how inconsistent the ECMWF has been. ...Weather Highlights/Threats... Below average temperatures in the East will slowly moderate back toward more typical mid-November values by early next week. Much of the West will maintain near to above average temperatures by about 5-15 degrees. Coastal system should keep the heaviest rains offshore but this is dependent on the track/evolution of the system. Coastal showers (and breezy conditions) are expected per the current forecast. The precipitation shield will move northward into New England by next week. Several systems out of the Pacific will maintain a rather wet period for at least coastal Washington/Oregon and the Cascades, with less rain/snow along and just west of the Divide. Fracasso Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are 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 https://www.wpc.ncep.noaa.gov/heat_index.shtml