Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Fri Oct 25 2024 Valid 12Z Mon Oct 28 2024 - 12Z Fri Nov 01 2024 ...Heavy snow threats for the West/Northwest next week may focus over the central Rockies Tuesday. Lead central U.S. heat to then be replaced by a cold/windy post-frontal airmass as frost/freeze issues spread from the West into later next week... ...General Overview... An amplified upper-level trough set to dig into the West this weekend will spread highly unsettled weather across much of the western U.S. early next week to include high-elevation snow, gusty winds and colder temperatures. This trough will then push eastward against expansive/warm central to eastern U.S. upper ridging; resulting in a wavy sharp front for the mid-section of the country where a moderately heavy rain event appears to emerge from the Plains through the Mississippi Valley and Midwest by next midweek. ...Guidance/Predictability Assessment... Latest GFS/ECMWF/UKMET/Canadian model guidance seems well clustered through early to mid next week and enjoys good ensemble and National Blend of Model (NBM) support, bolstering forecast confidence. A composite solution seems to well mitigate lingering system timing differences next week, albeit with favored slow transition from the models to a blend of the NBM and compatible GEFS/ECMWF ensemble means. This holds good WPC product continuity. ...Weather/Hazards Highlights... A cold front associated with a digging upper-level trough from the Pacific will increasingly work inland over the West into early next week. Periods of rain, high- elevation snow, windy and colder conditions are expected to overspread much of the rest of the western U.S. through early next week along/behind the front, with high winds set to impact the southern Rockies and southern High Plains as the colder airmass digs into the region. This may also lead to some frost/freeze concerns. Modest cyclogenesis across the Canadian prairies will advance a front across the northern Plains and upper Midwest through early next week. This front is forecast to sharpen with time as it continues to push against an expansive high pressure system anchoring across the eastern and southern U.S. Snow will appear to linger over the northern to central Rockies and into the northern High Plains behind a low pressure wave where accumulating snowfall appears likely. Ahead of the sharpening front, a long fetch of return flow from the Gulf of Mexico could lead to a moderate to heavy rain event to emerge across the mid- Mississippi Valley to the Midwest with embedded thunderstorms by midweek next week especially if a low pressure wavy is able to consolidate along the front. In the meantime, precipitation associated with the next Pacific system is forecast to move into the Pacific Northwest during midweek next week. The digging trough in the West will be mirrored by a staunch downstream ridge over the central to eastern U.S. next week. This ridge will support temperatures between 20-30 degrees above average across the Plains on Monday before spreading into the Mississippi Valley and Midwest/East into Tuesday, Wednesday and Thursday. There's also a potential for widespread temperature records to be tied or broken across from Arizona to Texas on Sunday followed by an expansion of this into the Plains and Upper Midwest. 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 forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw