Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 PM EST Thu Feb 10 2022 Valid 12Z Sun Feb 13 2022 - 12Z Thu Feb 17 2022 ...Weather Pattern Overview... A rather significant pattern change is coming early next week as a strong trough, originating over the Gulf of Alaska, drops southeastward across the West Coast region. This will abruptly replace the long-standing upper ridge that will be over the western third of the nation through this weekend, which is expected to lead to surface cyclogenesis by the middle of next week across the western High Plains. This will tend to displace the ridge axis farther east across the Plains, although less amplified than before, and resulting in more of a quasi-zonal flow pattern across much of the central and eastern U.S. as the deep upper trough over the East Coast region lifts out by early-mid next week. Additionally, there will be an offshore low that develops off the East Coast for late Sunday and then lifts northeastward to Nova Scotia and Newfoundland, with increasing chances for snow across parts of the Mid-Atlantic and Northeast. ...Guidance Evaluation/Predictability Assessment... The 00Z deterministic model guidance is in very good agreement on the expected synoptic scale evolution of the western U.S. trough that builds in for early next week. However, there are still some model differences with shortwave energy crossing the eastern U.S. through early Monday and its role in offshore surface cyclogenesis. The latest 12z CMC run was too fast and weak compared to the other 12z deterministic runs, with respect to the Pacific shortwave arriving over the West Coast on Monday. By Tuesday it appears to form a pair of embedded closed lows within the same trough. By Wednesday, it comes into better agreement with the other models. The WPC fronts/pressures forecast was primarily derived from a general model blend through Monday, and then gradually increasing percentages of the means through the middle of next week. ...Weather Highlights/Threats... An offshore low is expected to develop along the exiting cold front on Sunday as shortwave energy from an approaching upper level trough induces cyclogenesis. There has been some run-to-run variance in the guidance over the past 24 hours, but this still keeps the majority of the precipitation off the coast. However, some snow is becoming increasingly likely for portions of eastern New England and also across parts of the Delmarva and into Virginia. This may begin as a cold rain before changing to snow. Later in the forecast period across the central U.S., widespread showers and thunderstorms are likely to develop by Wednesday into Thursday as the surface low develops further across the Plains and advects substantial moisture from the Gulf of Mexico northward into the Mississippi/Tennessee Valley and Southeast, with some strong storms possible in this type of synoptic scale set-up. There may also be some accumulating snow on the northern periphery of this low pressure system across portions of the Midwest and Great Lakes. In terms of temperatures, below average readings are expected by Sunday and into early next week for the eastern U.S. as the strong cold front ushers in a renewed round of cold weather. Highs up to 20 degrees below normal are possible for portions of the Great Lakes region this weekend. It should be mild once again across most of the Plains for Sunday and into Monday with the West Coast region beginning to cool down with the trough building in, after anomalous warmth across portions of California this weekend. Kebede/Hamrick 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