Extended Forecast Discussion NWS Weather Prediction Center College Park MD 159 PM EST Tue Feb 08 2022 Valid 12Z Fri Feb 11 2022 - 12Z Tue Feb 15 2022 ...Weather Pattern Overview... Guidance continues to advertise persistence of an amplified East Pacific/West Coast upper ridge and downstream mean trough through the weekend, followed by a significant pattern change early next week as a trough initially tracking across the North Pacific drops into the West ahead of a newly building Pacific upper ridge. This evolution will ultimately lead to a flatter trend for downstream flow, with the initial western ridge migrating through the western/central U.S. and the eastern trough departing from the East Coast by next Tuesday. The forecast pattern will tend to favor below-average coverage and intensity of precipitation over the lower 48. Parts of the West will see well above normal temperatures late this week into the weekend before a cooling trend while some areas farther to the east may see some notable temperature swings over the course of the period. ...Guidance Evaluation/Predictability Assessment... Models and ensembles agree on the large scale pattern evolution but embedded detail uncertainties persist. These issues involve specifics of initial upper trough energy crossing the eastern half of the country/eventual western Atlantic surface development, upstream energy dropping into the mean trough/associated surface pattern, and distribution/timing of North Pacific shortwave energy expected to push into the West next week. Thus far the consensus indicates that the eastern trough aloft will remain sufficiently open to keep a potential western Atlantic system far enough offshore not to bring meaningful precipitation to the Mid-Atlantic and Northeast around Sunday-Monday. However a minority of ensemble members could still suggest a lingering low-end potential for moisture to extend farther westward. Meanwhile models have been varying considerably for specifics of the surface pattern over the central/eastern U.S. behind this system. At least the 06Z GFS/GEFS and 00Z ECMWF/ECMWF mean runs arrived at similar ideas for the next wave so their scenario provides the most likely option at this time. Operational model runs have also been erratic with the details of Pacific energy coming into the West. Again the aforementioned models/means showed reasonable agreement in principle, bringing an open shortwave into the West, while individual stray runs such as the 00Z CMC pulled off a low offshore. The 00Z ECMWF could be a little too amplified though. The new 12Z CMC has adjusted to the model/mean consensus and the 12Z ECMWF has toned down its trough amplitude. Based on the guidance comparisons through 06Z data, an operational model blend with greater emphasis on the 06Z GFS/00Z ECMWF transitioned to a model/mean mix among the GFS/ECMWF and their respective means. Maintaining continuity, QPF stayed closer to the operational model scenario near the East Coat around Sunday-Monday. PoPs represented a compromise between the wetter ensemble means and fairly dry operational guidance. ...Weather Highlights/Threats... A strong but progressive clipper type low pressure system will cross the northern Great Lakes on Friday and then track into northern New England/eastern Canada by Saturday, spreading snow across the Great Lakes and mostly light rain farther south and east. Expect breezy to windy conditions across the Upper Midwest and Great Lakes region as this low moves through the region. Parts of the Plains/Rockies could also see a brief period of brisk winds as a couple cold fronts push southward. Trailing Canadian surface high pressure dropping southward across the central U.S. will deliver dry conditions to much of the nation for the upcoming weekend. It appears likely that low pressure will develop off the East Coast Sunday-Monday but the system is likely to be far enough offshore to keep most of the precipitation and wind away from land. The upper trough and leading front reaching the West early next week should bring an area of precipitation (mostly light to moderate) and possibly strengthening winds to the region. Coverage and timing of rain and mountain snow will depend on system details that remain somewhat uncertain. A majority of the West will see above normal temperatures from late this week through the weekend. Expect the warmest anomalies (plus 10-15F and locally higher) to be centered over and near California where high temperatures may challenge or exceed daily record values. Then the upper trough/leading cold front moving into the West early next week will bring a cooling trend, ultimately leading to highs within a few degrees F on either side of normal by next Tuesday. Farther to the east, the Plains should see plus 10-20F anomalies for max and/or min temperatures on Friday. Frontal passage will bring a brief cooler period during the weekend followed by temperatures rebounding to 5-20F above normal early next week. The eastern U.S. will see its warmest temperatures of the period Friday-Saturday ahead of the approaching front. Plus 5-15F anomalies will be common and parts of the Northeast could see lows 20F or more above normal on one or both days. The cold surge behind the front will reach the Mississippi Valley by Saturday and then continue toward the East Coast, leading to one or more days of max/min readings of 10-20F below normal with coldest anomalies tending to focus over the northern half of the East. Rausch/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, 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/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml