Extended Forecast Discussion NWS Weather Prediction Center College Park MD 330 PM EST Wed Jan 19 2022 Valid 12Z Sat Jan 22 2022 - 12Z Wed Jan 26 2022 18Z Update: The overall trend in the 12Z model guidance suite is for a faster and slightly more suppressed surface low that tracks out to sea by Saturday morning, with any lingering precipitation coming to an end across the coastal Mid-Atlantic by mid-day Saturday. There is no indication that this storm will have any significant impacts for the Northeast U.S. at this time. For the closed low that ejects from the Southwest to the Gulf Coast region, the CMC is on the fast side of the model guidance with the arrival of the trough to the northern Gulf early next week, and there has been a gradual increase in the QPF expected from the associated low that develops along the front across the central and western Gulf Coast region. By the end of the forecast period, this storm system will likely head east across Florida and then out to sea. The WPC fronts/pressures forecast was primarily derived from a multi-deterministic blend through early Monday, and then incorporated some of the NAEFS/ECENS for days 6 and 7. The rest of the forecast remains on track and the previous forecast discussion is appended below for reference. /Hamrick ______________________________ ...Pattern Overview and Guidance/Predictability Assessment... Guidance remains in good agreement with the mean flow over the lower 48 highlighted by an amplified upper ridge off/along the West Coast and an amplified and unsettling upper trough over the central to eastern U.S. that coincides with several short and medium range Arctic blasts with periods of much below normal temperatures. The models have been less than stellar with the run to run continuity of embedded shortwaves rotating through the mean upper trough position and surface system reflection, but seem to be slowly improving. Given lingering model variance issues however, the earlier released WPC medium range product suite was primarily derived from the 12 UTC GEFS mean and especially the ECMWF ensemble mean along with the 01 UTC National Blend of Models. The 00 UTC models seem to be converging on better clustered solutions that have overall trended favorably toward the WPC composite solution, bolstering forecast confidence. ...Weather Highlights/Threats... 00 UTC forecast guidance is better clustered with an important shortwave trough exiting the Mid-Atlantic Saturday that offers potential for coastal storm development. The 00 UTC models better agree with development of an organized low off the Mid-Atlantic and New England. The WPC Winter Weather Outlook holds a lingering chance for coastal snows into Day 4/Saturday with the exiting low given the threat of a few more robust ensemble members. Upstream, models generally agree to carve out a Southwest U.S/northern Mexico closed low by Saturday that offers terrain enhanced snow potential from the Mogollon Rim to the southern Rockies/High Plains. The system remains slated to be ejected eastward across the U.S. southern tier early next week. Lead moisture return from the Gulf of Mexico will overrun a trailing/wavy front to fuel a decent swath of precipitation within a cooled airmass from Texas eastward across the Gulf Coast. 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 Hazards: - Flooding occurring or imminent across portions of the Lower Mississippi Valley. - Much below normal temperatures across portions of the Southern Plains and the Southwest, Sat-Sun, Jan 22-Jan 23. - Much below normal temperatures across portions of the Northern/Central Plains, the Upper/Middle Mississippi Valley, and the Great Lakes, Sun-Wed, Jan 23-Jan 26. - Much below normal temperatures across portions of the Northeast, the Central/Southern Appalachians, the Tennessee Valley, the Mid-Atlantic, the Southeast, and the Great Lakes, Sat, Jan 22. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat, Jan 22. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Jan 23-Jan 24. - High winds across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 24. 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