Extended Forecast Discussion NWS Weather Prediction Center College Park MD 147 AM EST Fri Dec 13 2019 Valid 12Z Mon Dec 16 2019 - 12Z Fri Dec 20 2019 ...Wintry weather early next week from the central Plains to the Northeast..with heavy rain over parts of the interior Southeast... ...Pattern Overview and Guidance/Predictability Assessment with Weather Highlights/Threats... A low pressure system will likely bring a swath of wintry precipitation early next week from the central Plains to the Northeast as a shortwave trough ejecting out of the Rockies interacts with a cold front. Models are in decent agreement on this scenario with the GFS showing somewhat faster development and forward speed of the low than other models. Areas of heavy rain will also be possible across the interior Southeast before the front moves off the East Coast Tuesday night. The air mass behind the low will not be tremendously cold, although much of the eastern two-thirds of the country will be colder than normal through midweek next week. Meanwhile, models are indicating that a Pacific cyclone will approach the West Coast by the middle of next week. The GFS again shows a faster forward motion with this system than other models. More of the ensemble mean solutions were used to handle the uncertainty. The WPC medium-range forecast grids were a consensus of the 00Z ECMWF/EC mean with a blend of the 12Z/18Z GFS as well as the 18Z GEFS. Precipitation ahead of the cyclone should first reach the coast of California and the Pacific Northwest on Wednesday, followed by slow inland progression of the precipitation as the system is forecast the gradually weaken near the West Coast. The higher elevations of California such as the Sierra Nevada should see some wet snow on Wednesday into early Thursday. The chance of snow will also be on the increase from the Cascades to the Intermountain region late next week. In addition, the snow along the Cascades could become heavy on Friday. Also by late next week, models are beginning to indicate the return of Gulf moisture across southern Texas where a coastal front may be forming. Kong 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