Extended Forecast Discussion NWS Weather Prediction Center College Park MD 154 PM EST Tue Feb 25 2025 Valid 12Z Fri Feb 28 2025 - 12Z Tue Mar 04 2025 ...Overview... Overall it generally remains the case that the medium range continues to feature a rather progressive overall flow pattern. Troughing over the East on Friday will be reinforced again this weekend by a shortwave through the Upper Midwest. Meanwhile out West, a cutoff upper low will slide into southern California on Friday, across the Southwest this weekend, and weaken and get absorbed into the larger scale flow early next week over the southern Plains and generally eastward as per trends from 12 UTC guidance. Behind this, another deep trough or upper low will move into the West Coast Sunday into Monday, with general indications of a more amplified pattern over the West to Central U.S. next week. ...Guidance/Predictability Assessment... Recent guidance cycles continue to show good agreement on the overall pattern progression and dominant features of the medium range period, but with uncertainty in the details. Two main sources of uncertainty lie with the pair of upper lows through the Western U.S. this weekend and again next week. The first, into southern California on Friday, has shown improved consistency in the timing, but there is variability in the track. The last few GFS runs remains notably displaced north of the UKMET, CMC, and ECMWF. The EC-based AI models were also varied and thus suggesting that either placement was less likely but plausible. For the second trough early next week, the guidance agrees on its existence but there's considerable uncertainty in the timing and evolution. The 12 UTC ECMWF was on the faster side, with the trough over the Central U.S. by next Tuesday. The newer 12 UTC ECMWF has slowed down some. Recent GFS runs, however, still have the main trough over the West by that time. CMC runs offer an in between solution, slightly faster than concensus. Ensemble means generally sided with their deterministic counterparts, but closer to consensus. The preferred WPC blend used a multi-model blend the first few days of the period for Friday/Saturday, transitioning Sunday to an ensemble mean blend for next Monday/Tuesday. This acts to maintain reasonably good WPC product continuity amid lingering uncertainty. ...Weather/Hazards Highlights... A clipper system should bring a round of precipitation to the Great Lakes and Northeast Friday into Saturday, with moderate snowfall possibly enhanced by the lake waters across the upper Great Lakes, with mixed precipitation just to the south. A period of strong and gusty winds can also be expected on Friday across the northern Plains and perhaps into Saturday near the Great Lakes on the back-side of the system as cold air rushes in behind it. A building ridge should keep conditions quiet and dry across the West into Friday. 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. There appears to be a better signal for the precipitation to spread farther east/northeast across the southern Plains Sunday into Monday, and with much more uncertainty into the east-central U.S. through early next week to monitor given ambient moist soil conditions. The northern stream trough moving through the eastern Pacific and into the West next weekend will also bring precipitation chances back for the West Coast, spreading across the Great Basin/Rockies early next week. Much above normal temperatures will be well established by Friday across the West and into the northern/central Plains. The greatest anomalies will be across the northern Plains with daytime highs 20 to locally 30 degrees above normal, with 60s for highs as far north as Nebraska/South Dakota. The above normal temperatures will spread south and east, with the West trending cooler by early next week. Across the East, temperatures will vary between normal and above normal into Saturday, but be mostly below normal Sunday and Monday in post-frontal high pressure before again moderating. Santorelli/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 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