Extended Forecast Discussion NWS Weather Prediction Center College Park MD 156 AM EST Sat Jan 18 2020 Valid 12Z Tue Jan 21 2020 - 12Z Sat Jan 25 2020 ...Overview... As upper troughing exits the Southeast on Tuesday, another will approach the Pacific Northwest. This will dig through the Rockies and into the Southern Plains by Thursday, increasing the threat of rainfall and northern fringe snow for the eastern half of the CONUS through Saturday. A couple other Pacific fronts will bring some snow/rain to the Northwest late next week. ...Guidance/Predictability Assessment... The models/ensembles were in generally good synoptic agreement with the longwave flow and progressive and modestly amplified pattern. The GFS/GEFS had generally trended toward the more consistent (but not totally consistent) ECMWF/ECMWF ensembles but the latest 12Z/18Z runs were more in line. Differences lied in the depth/speed of 1) the exiting Southeast upper trough Tue/Wed (GFS/GEFS quicker, ECMWF slower), 2) northern stream shortwave across Ontario Wed, and 3) north-south location of low pressure in the Lower MS Valley or northern Gulf Coast region Fri-Sat. Favored the ECMWF-led consensus with support from the Canadian and UKMET to varying degrees early in the period before forming an ensemble consensus with the southern system that lied near the 12Z Canadian. With a bit of divergent trends between the GEFS/ECMWF ensembles, a middle-ground solution seemed prudent. ...Weather/Hazard Highlights... Lingering below normal temperatures over the Upper Midwest/Corn Belt (owing to new snowfall in the short term) will moderate Wednesday onward as southerly flow brings in milder air (5-15 deg above normal). This will work its way to the East Coast by Friday into Saturday ahead of the Gulf system. Precipitation in the Northwest Tuesday will be a nearly daily occurrence with several systems to push through. Thursday may be the rainier/snowier day of the 5-day period which will see several inches of precipitation in favored areas. Rainfall will expand over Texas and points eastward/northeastward starting Tuesday with help from leftover mid/high-level moisture from a weak Pacific system racing across Mexico. Then as the surface cold front organizes over Texas Thursday, some Gulf inflow will help realize modest rainfall totals along the Gulf coast with uncertainty to its northward extent. Some amounts could be locally heavy. The system may have some wintry weather on its northern side from the Central Plains to the Great Lakes. 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