Extended Forecast Discussion NWS Weather Prediction Center College Park MD 247 AM EDT Fri Oct 04 2019 Valid 12Z Mon Oct 07 2019 - 12Z Fri Oct 11 2019 ...Another round of cold/snow for portions of Montana next week... ...Overview... Troughing will exit the Northeast but enter the Pacific Northwest early next week as a fairly amplified but progressive flow pattern continues. Western troughing will push through the central states next Thu/Fri with much below average temperatures in its wake. ...Guidance/Uncertainty Assessment... The 12Z/18Z GFS and 12Z ECMWF offered reasonable clustering near their ensemble means and each other such that a blend sufficed through the period. Typical differences within expected errors for 3-7 day lead times suggested at least average confidence. By later next week, the ECMWF and its ensemble members were generally quicker with the central CONUS trough than the 18Z GFS/GEFS but there was quite a bit of east-west spread by next Fri depending on the wavelength amplitude of the member--the slower members (with a deeper trough or closed low lingering in the West) were generally slower downstream with another closed low near the New England coast (like the 12Z Canadian). For now, GFS/ECMWF/ensemble consensus was progressive enough to keep the surface front moving through the week. ...Weather Highlights/Threats... Cold front nearing the East Coast will provide a focus for locally modest to heavy rainfall from the central Appalachians into the Northeast Monday. This rainfall will be beneficial over areas currently experiencing drought of varying intensity. Brief warm-up (70s on the coastal plain, 60s inland) will be replaced by near average temperatures for the rest of the week in much of the East. By Tue-Thu the front should settle over the Florida Peninsula and possibly lead to some rainfall enhancement in its vicinity. The upper trough dropping southeastward from the Gulf of Alaska will bring a period of rain and initially higher elevation snow to the Northwest during the first half of next week with highest totals over favored westward-facing terrain. Winter Weather Outlook snowfall probabilities exceed 70% (> 2-3" snow) over higher elevations on Tuesday in western Montana around Glacier Park. The cold air behind the leading surface front will progress southward and eastward which will lower snow levels toward or into the valley locations of the rest of Montana. High temperatures are likely to be at least 10-20F below average over the northern Rockies/Plains on Wed and over much of the northern-central Plains by Thu. This will spread southward to Texas and eastward to the Mississippi Valley by Friday but perhaps with less intensity. Rainfall will expand and perhaps become locally heavy over the mid-Mississippi Valley late in the period depending on moisture inflow from the Gulf. 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