Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 AM EDT Sat Apr 16 2022 Valid 12Z Tue Apr 19 2022 - 12Z Sat Apr 23 2022 ...Weather Pattern Overview... There will be three well-defined storm systems that will affect the continental U.S. next week. The first will be a coastal low near the Northeast U.S. coast on Tuesday that will intensify as it lifts northward towards eastern Quebec, bringing rain, wind, and mountain snow to New England. A large surface high will then encompass the eastern half of the nation through Wednesday ahead of the next developing storm system over the Plains, which should result in another cold front reaching the East Coast by Friday. The third system develops over the West Coast and Intermountain West region for the end of the week as an amplified upper level trough builds in from the Pacific, along with a downstream upper ridge axis over the Plains. ...Model Guidance Evaluation... The 00Z model guidance suite is initially in very good overall agreement through the early-middle part of next week with above average confidence, and although mesoscale differences become more apparent going forward, the overall synoptic scale depiction remains good through the remainder of the week and into Saturday. By Thursday, the GFS becomes more progressive with the shortwave/surface low crossing the northern tier states, but is very close to its ensemble mean. For the end of the week, the CMC holds the axis of the upper trough farther back to the west compared to the ECMWF and the ensemble means, whereas the GFS is faster to lift the trough out of the Intermountain by Saturday. The WPC forecast was primarily derived from a multi-deterministic blend through Wednesday, and then gradually incorporated more of the ECENS/GEFS means for the latter half of the forecast period. ...Sensible Weather/Threats... In the precipitation department, the West Coast region is expected to remain rather unsettled with two well defined events. The first round of rain and mountain snow is expected late Monday into Tuesday from northern California to Washington state, and the second and more impactful system arriving Thursday and early Friday, extending farther south into central California and also affecting areas to the north. This late season event will deliver highly beneficial precipitation to drought-stricken areas of California, with the potential for up to three inches of rain in some areas next week, and 1-3 feet of snow for the Sierra. Elsewhere across the continental U.S., the surface low near New England is expected to result in widespread rain, wind, and potentially moderate to heavy snow for the higher terrain of the Adirondacks and extending to northern Maine through Tuesday afternoon. Another round of organized showers and storms is likely to develop across the central U.S. and extending northward to the Great Lakes by midweek as Gulf moisture is advected northward ahead of the organizing storm system over the central Plains. Additional moderate to heavy snow is also expected for portions of the northern Rockies for the end of the week. Temperatures are expected to remain rather chilly from the northern Plains to the Great Lakes and Appalachians through about Wednesday, and these below average readings may persist even longer across North Dakota and northern Minnesota going through the end of the week. On the contrary, warm conditions are currently expected across much of the interior western U.S. for the majority of the forecast period ahead of the upper trough, with well above normal readings probable across the western High Plains by the end of the week and into Texas. Temperatures should also moderate for the Eastern U.S. by Thursday as the surface high moves off the coast and warmer southerly flow commences. Windy conditions are also likely from western Texas to the western Dakotas on Tuesday with strong southerly flow 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