Extended Forecast Discussion NWS Weather Prediction Center College Park MD 154 PM EST Tue Feb 20 2024 Valid 12Z Fri Feb 23 2024 - 12Z Tue Feb 27 2024 ...Overview... An upper ridge traversing the country late this week into early next week will spread much above normal temperatures particularly to the Plains and Midwest. Troughing will be in place across the East late this week ahead of the ridge, with some precipitation across the Eastern Seaboard Friday and cooler temperatures by Saturday behind a cold front, before transitioning to more zonal flow. Meanwhile an eastern Pacific upper low should spread some increasing precipitation chances to the West Coast once again, possibly by the weekend but more confidently by early next week as northern and southern stream troughing phase and track into the West. ...Guidance/Predictability Assessment... Overall, the model guidance continues to show above average agreement on the large scale pattern, but some inconsistencies in the details. There are some minor differences early on with weak shortwaves through the Northeast but a general model compromise seems to smooth these out and provide a good starting point. Out West, the Sunday-Tuesday period presents some uncertainties with northern stream energy through the Pacific Northwest and then the details of eventual phasing with the upper low that meanders off the southern California coast late this week/weekend. By next Tuesday, the CMC is noticeably faster than the GFS/ECMWF (and ensemble means) with an eventual amplified trough through the West and was excluded from the late period blend today. WPC used a blend of the deterministic guidance for the first half of the period, eventually transitioning to a 50/50 blend of the deterministic (GFS and ECMWF) with the ensemble means by day 7. This also maintained good continuity with the previous WPC forecast as well. ...Weather/Hazards Highlights... Light to moderate precipitation is forecast for the Eastern Seaboard on Friday ahead of a cold front. Higher elevations of New York and New England have relatively higher probabilities of seeing notable snow with this activity but the details of the exact low track and temperatures will determine placement and amounts of snow. Brisk winds are also possible for New England particularly late Friday into Saturday as the surface low strengthens. Behind this system, parts of the Great Lakes may see mostly light snow from a combination of lake effect and lake enhanced activity caused by nearby fronts this weekend into early next week. An upper low and its surface reflection look to meander in the eastern Pacific late this week, perhaps reaching close enough to California to provide some shower activity. But by Sunday model guidance is more agreeable that precipitation should spread into the Pacific Northwest and California with some moisture spreading farther inland into the Intermountain West. Snow and rain should continue to increase in interior parts of the West into Monday/Tuesday, with potential for gusty winds to accompany this overall system. Another low pressure/frontal system also should provide forcing to increase precipitation (mainly in the form of rain given the anomalous warmth) in the Midwest. Warmer than average temperatures by 10-20 degrees in the central U.S. on Friday look to only increase in coverage and magnitude by the weekend and early next week. Temperatures of 20-30F above average will stretch from the northern Plains/Upper Midwest Saturday southward into the Plains and Mississippi Valley early next week. This puts actual temperatures into the 80s and even 90s in Texas Monday-Tuesday while 50s and possibly even 60s reach the Dakotas. A gradual eastward spread/shift should warm the Southeast in to the 70s next week. The East looks to be above average Friday but near to below average Saturday behind a cold front, and gradually warming again next week. Meanwhile the West is forecast to see near to slightly above normal temperatures late week into the weekend, but cooling to below normal particularly in terms of highs by Monday-Tuesday as upper troughing comes in. Santorelli/Tate 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, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages 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 https://www.wpc.ncep.noaa.gov/#page=ovw