Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Thu Feb 21 2019 Valid 12Z Sun Feb 24 2019 - 12Z Thu Feb 28 2019 ...Major Upper Midwest/Great Lakes/Interior New England Winter Storm Sunday/Monday... ...Guidance/Predictability Assessment and Preferences... Guidance was reasonably well-clustered at mid-larger scales through the medium range period and a composite blend of the latest ECMWF/UKMET/Canadian and ECMWF ensembles offers a reasonable starting point for the forecast. The GFS and GEFS are less robust to bring lower level colder air southward next week and their solutions were downplayed as the FV3 showed an opposite trend more in line with the other guidance. ...Weather Highlights/Hazards... A threat for significant snows/some icing exists around a deep surface low. The rapidly deepening system (central pressure fall of about 20mb/24 hrs between Sat and Sun morning) lifts into the Great Lakes and then exits out the St. Lawrence Valley Sunday into Monday. This system has the potential to deepen into the upper 970s mb or at least low 980s mb which may be close to monthly record low pressure values for portions of Lower Michigan Sunday. Expect strong/gusty winds and potential blizzard conditions over the Upper Midwest/Great Lakes and into Canada Sunday-Monday. Mild air will surge northward east of a trailing cold front with a brief spike in temps to the 60/70s as far north as the Mid-Atlantic. Farther south, a prolonged heavy rain pattern will finally end with cold frontal passage, with lead record warm temps possible over Florida. A long-standing and wintry mean upper trough over the West deamplifies next week, but will still be reinforced over the Northwest into Sun-Mon as energy undercuts and digs to the lee of a blocking Alaska-centered closing upper high. This will bring unsettled weather across the Northwest/Northern CA and the north-central Intermountain West/Rockies. The best chance for heavy snow will be from the Cascades to especially northern CA with emergence of uncertain Pacific flow undercutting the northern stream. Flatter flow downstream over central and eastern U.S. next week reduces potential for big storms, but a series of smaller/less predictable systems will progress over the region. This will still favor cold air surges/anomalously cold temps through the n-central U.S. and snow swaths over the northern tier states. Rainfall also redevelops across the Gulf Coast/FL with the fronts, but guidance has backed off with amounts. Schichtel WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation and winter weather outlook probabilities are found 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