Extended Forecast Discussion NWS Weather Prediction Center College Park MD 256 AM EDT Fri Apr 15 2022 Valid 12Z Mon Apr 18 2022 - 12Z Fri Apr 22 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 surface low over the Great Lakes with a trailing cold front that will reach the East Coast around Monday night, with a triple point low likely developing near the Northeast U.S. on Tuesday. 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 next 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, and although mesoscale differences become more apparent going forward, the overall synoptic scale depiction remains good through the remainder of the week. One of the more noticeable changes in the guidance is with the 00Z ECMWF being much more progressive with the building trough over the western U.S. by next Friday compared to its prior 12Z run, and also ahead of the 00Z model consensus. Therefore the 12Z ECMWF would be preferable for the central/western part of the U.S. instead of the latest 00Z run. The 00Z GFS/CMC/GEFS appear to handle that trough well, along with the 12Z ECENS/ECMWF. The WPC forecast was primarily derived from a multi-deterministic blend through Tuesday, and then gradually incorporated more of the ECENS/GEFS means for the latter half of next week. ...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 arriving Thursday and early Friday, extending farther south into central California and also affecting areas to the north. This will be 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 1-2 feet of snow for the Sierra. Elsewhere across the continental U.S., showers and thunderstorms will be exiting the East Coast region early in the week, followed by dry weather as high pressure settles into the region. Another round of organized showers and storms is likely across the central U.S. by midweek as Gulf moisture is advected northward ahead of the organizing storm system over the central Plains. Temperatures are expected to remain rather chilly from the northern Plains to the Great Lakes and Appalachians through much of the upcoming week, and these below average readings should also include much of the East Coast region through about Wednesday as the cold Canadian surface high governs the weather pattern. On the contrary, warm conditions are currently expected across much of the interior western U.S. for the majority of the forecast period, with above normal readings probable across the central and southern Plains on Wednesday ahead of the cold front. Temperatures should also moderate for the Eastern U.S. by Thursday as the surface high moves off the coast and warmer southerly flow commences. 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