Extended Forecast Discussion NWS Weather Prediction Center College Park MD 142 PM EST Thu Jan 16 2020 Valid 12Z Sun Jan 19 2020 - 12Z Thu Jan 23 2020 ...Guidance/Predictability Assessment... Troughing in the East will gradually shift into the Atlantic next week as Pacific troughing moves into the Northwest midweek. Ridging over the Rockies will weaken as it slips eastward to the Plains. The overall pattern will be much quieter than the short term in the East but remain active in the West with a main system on Tuesday. The models/ensembles were in good agreement to start the period and a deterministic consensus sufficed for Sunday with the exiting eastern system. Models continue to struggle with the next system entering the Northwest by Tuesday, including a potential surface low offshore on Monday. The GFS (and to some extent the GEFS) continue to be the farthest south with the surface low/upper low, with the ECMWF the farthest north. The UKMET/CMC and ECENS mean are all a bit south of the ECMWF position, though not as far south as the GFS. Greater differences emerge with evolution of this system as it shifts inland Tuesday into Wednesday eventually reaching the Southern Plains early Thursday as a potential closed low, though run to run continuity with this is not great at this point. Increasing weighting of the ensemble means is preferred beyond day 4 to handle the uncertainty. Continued smaller contributions of the ECMWF and a bit of the GFS just for some definition. This maintains good continuity with the previous WPC forecast. This brings the western front through the Great Basin/northern Divide and to the Southern Plains by the end of the period, with rising heights in the East. ...Weather/Hazard Highlights... The eastern half of the CONUS will be near to below normal temperatures early next week behind the exiting Northeast system, with the greatest anomalies (-20 to -30F from normal) centered over the northern Plains/Upper Midwest Sunday-Monday. With the eastern U.S. cold front expected to push south of Florida, even the sunshine state will see high temperatures only in the 60s and low 70s at best all the way to the Keys. High temperature anomalies of 10-20F below normal will ease after Tuesday back toward more typical January values in the East, with some above normal temperatures moving into the High Plains/Upper Mississippi Valley next Wednesday and Thursday. Precipitation will be limited in the East to around the Great Lakes and across Florida early in the period. Main western front will bring in modest lower elevation rain/higher elevation snow to WA/OR and northern/central CA with lighter amounts east of the Cascades/Sierra Tuesday, followed by lighter precipitation Wed-Thu. By next Wed-Thu, Gulf moisture should increase rain chances over Texas northward and northeastward as a front approaches the area from the northwest with some models indicating heavy rainfall potential. Santorelli 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