Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Sat Jan 30 2021 Valid 12Z Tue Feb 02 2021 - 12Z Sat Feb 06 2021 ...Winter Storm for the Mid-Atlantic/Northeast early next week and from the West to the Midwest/Northeast mid-later next week... ...Weather/Threats Highlights and Guidance/Predictability Assessment... For the major coastal storm persisting early next week, a signal for heavy snowfall remains from the interior Mid-Atlantic to southern New England, bolstering mid-larger scale forecast confidence. Some areas along or offshore the coast should also see a period of brisk to strong winds. This deepened low will also remain a significant maritime threat. Guidance meanwhile agrees to dig a strong upper trough into CA Tue-Wed to support a period of enhanced moisture/rains and heavy Sierra snows, with more modest enhanced amounts focusing on favored terrain and with deformation for the cooled south-central Great Basin/Rockies. Variance with the extent of digging leads to subsequent ejection differences. Differences grow downstream along with uncertain stream phasing/central U.S. storm genesis mid-later next week. It is expected that as the energy comes out of the West and Rockies, a deepening low to the lee of the Rockies will to lift toward the Upper Midwest. Strong warm air advection and moisture return on the backside of the departing high will allow for copious amounts of moisture to work with the better dynamics and forcing. Over the central then eastern U.S., this offers a threat for heavy wrap-back snows to the north as per the WPC winter weather outlook, QPF and weather type grids along with an expanding area of enhanced warm sector/frontal heavy rains/convection farther south. Recent GFS and Canadian runs offer less than stellar run to run continuity. Recent ECMWF runs have tended to be on the slower/wrapped side of solution envelope, but have been more run to run consistent and a bit better clustered with ensembles. Given initial deep system amplitude over the West, the ECMWF and ECMWF/GEFS ensemble means were heavily incorporated into the WPC forecast product blend. Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook 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