Extended Forecast Discussion NWS Weather Prediction Center College Park MD 156 AM EST Mon Feb 27 2023 Valid 12Z Thu Mar 2 2023 - 12Z Mon Mar 6 2023 ***A series of active winter storms to threaten the West and a late week storm offers a heavy rain/severe weather threat across the southern to eastern states along with a snow/ice threat from the central Plains/Midwest to the Northeastern states*** ...Synoptic Overview... It remains the case that the month of March is expected to begin like a lion across much of the south-central U.S. as a potent southern stream disturbance generates a well defined surface low over the Southern Plains on Thursday, and then is forecast to track across the Mid-South and then exit the East Coast Friday night. A weaker lead disturbance is expected across the Northeast U.S. prior to this event on Thursday. Surface high pressure then builds across the Eastern U.S. in time for the weekend. Meanwhile, the West Coast region remains active with another low pressure system dropping south from the Gulf of Alaska by Saturday, and surface cyclogenesis is once again possible over the western High Plains going into Sunday night and Monday. ...Guidance/Predictability Assessment... Models and ensembles generally offer well clustered solutions into the end of the week and a GFS/ECMWF/UKMET seems to provide a good forecast starting point, although the CMC was a bit farther south with the low developing over Texas, so the 12Z run for fronts/pressures was given less weighting. The larger scale pattern evolution seems well forecast into the weekend and next Monday as well from the Pacific into the West, although there is some differences with individual shortwaves across the central to eastern U.S., albeit with less forecast spread than yesterday. ...Weather/Hazard Highlights... The Pacific Northwest and the northern Rockies will continue to remain rather unsettled and cold going into Thursday as the upper trough rebuilds, with heavy snow likely over the Cascades and northern Idaho. High winds are also a good possibility Thursday north of the evolving frontal boundary over the Central Plains where a strong surface high will be building in from the north. A deeper upper trough evolves over the West next weekend is expected to increase coastal rain and inland snow from northern California to Washington state. Heavy rain and thunderstorms are likely to develop across portions of the Mid-South and southern Appalachians late Wednesday into Thursday, and there is a Slight Risk area for Day 4 in the excessive rainfall outlook for portions of that area. Additional rainfall is becoming more likely going into the end of the week, and some of this may be heavy at times across the southeastern U.S., mainly from northern Mississippi to North Carolina where the best forcing for ascent is likely to reside. In terms of temperatures, much of the central/eastern U.S. should have readings of 10-20F above normal through Thursday. Readings should return to with 5 degrees of climatological averages by next weekend for most areas east of the Rocky Mountains. The West will see a persistent cool pattern through the weekend with the Intermountain West and Rocky Mountains most consistently having highs on the order of 10-20F below normal, but nothing all that extreme in terms of arctic blasts is currently expected. 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, experimental excessive rainfall outlook, 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/#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