Extended Forecast Discussion NWS Weather Prediction Center College Park MD 152 AM EST Mon Feb 24 2025 Valid 12Z Thu Feb 27 2025 - 12Z Mon Mar 03 2025 ...Overview... The upper flow pattern should remain rather progressive through much of the upcoming medium range period. A deepening surface trough into the East on Thursday and Friday, will eventually be reinforced by secondary energy next weekend. Meanwhile, a ridge axis over the West will be undercut by a southern stream cutoff low moving inland across Southern California and into the Southwest and southern U.S. this weekend and early next week. Another deep and elongated upper trough looks to move into the West Coast next Sunday or Monday, as upper ridging begins to fill in again over the East. ...Guidance/Predictability Assessment... There continues to be reasonable agreement on the large scale pattern during the medium range period, but still plenty of uncertainty in the details, some of which could have notable sensible weather impacts. There are still some lingering timing uncertainties on the trough across the East late this week, but a general model compromise between the GFS, ECMWF, and CMC guidance seemed like a good starting point. Out West, guidance has trended more consistent with the timing of a cutoff upper low into California on Saturday, but some disagreement downstream on how quickly it weakens and gets absorbed into the large scale flow over the Southern Plains. The most uncertain part of the medium range period is with the second elongated trough/upper low into the West Coast around Monday of next week. Through the 12z/18z Feb 23 model runs, the ECMWF and its ensemble mean were considerably faster than consensus, with several of the EC-based AI models also supporting a slower progression of the low. The late period WPC forecast leaned closer to the slower CMC and GFS along with the ensemble means, anchored by the NAEFS. ...Weather/Hazards Highlights... A cold front into the East will spread generally light to moderate precipitation into Thursday. Some precipitation could be snow in the northern part of the precipitation shield across the Interior Northeast. A clipper system should bring an additional round of precipitation to the Great Lakes and Northeast Friday into Saturday. A building ridge should keep conditions quiet and dry across the West Thursday and Friday, other than a little light precipitation possible in the Pacific Northwest. The southern stream upper low moving across southern California Friday and inland next weekend may lead to light showers over California, the Southwest, and into the south- central U.S., with increasing rain chances in the southern Plains by next Sunday as moisture increases. The northern stream trough moving through the eastern Pacific and into the West next weekend will also bring precipitation back into the forecast for the West Coast and Great Basin. Much above normal temperatures will be well established by Thursday across the West and into the northern/central Plains. The greatest anomalies will be across the Plains with daytime highs 20 to locally 30 degrees above normal, with 60s for highs as far north as Nebraska or perhaps even South Dakota at times. The above normal temperatures will spread south and east, with the West Coast trending cooler by early next week. Across the East, temperatures may initially be warm on Thursday, but should trend back towards normal (or below normal) by the weekend. Santorelli 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