Extended Forecast Discussion NWS Weather Prediction Center College Park MD 301 AM EDT Sun Mar 31 2024 Valid 12Z Wed Apr 03 2024 - 12Z Sun Apr 07 2024 ...Major New England Coastal Storm into Wednesday/Thursday with maritime hazards and high wind/coastal flooding/rainfall threats along with an inland heavy snow threat... ...Widespread precipitation/cooling pattern for the West midweek- late week to expand into the Plains next weekend... ...Guidance/Predictability Assessment... The 12 UTC ECMWF/UKMET/Canadian model, ECMWF/Canadian ensemble guidance and to a lesser extent 18 UTC GFS/GEFS Canadian ensemble solutions check-in reasonably well clustered with the mid-larger scale flow evolution and main flow embedded weather systems slated to impact the lower 48 and vicinity next week in a stormy pattern with above normal predictability despite some lingering system timing and track variances. Prefer a model and ensemble mean blend with emphasis applied to the 12 UTC ECMWF given best ensemble support. This blend tends to provide detail while reasonably mitigating these differences consistent with individual predictability. Latest 00 UTC model and ensemble solutions are generally in line into next weekend. WPC product continuity is well maintained with this plan. ...Pattern Overview and Weather/Hazards Highlights... The pattern into Wednesday will feature cyclogenesis over the eastern U.S., with New England to be most strongly impacted with development of a significant Nor'easter into Thursday. This will present a threat for coastal flooding/heavy rains and inland heavy snows as highlighted in the WPC Winter Weather Outlook. While snow will be the primary precipitation type inland, protracted fetch off the Atlantic with this deep low may keep near coastal areas warm enough near the ground for sleet and heavy rain. Given wet ambient soils, introduced a Day4/Wednesday WPC Excessive Rainfall Outlook Marginal Threat area for eastern/southeastern New England. Toward the end of next week, models show excellent agreement on a highly-amplified upper pattern across the U.S. with a ridge building over the central U.S. as the deep low slowly pulls out of the Northeast and the next upper trough digs just off the West Coast. This strongly amplifying upper trough/closed low and leading and wavy cold front/secondary Canadian cold surge digging into the West should act to cool temperatures and spread enhanced precipitation and windy/unsettled flow to include coastal rains down through California along with a prolonged period with interior and terrain/mountain snows increasingly inland across much of the West midweek into next weekend. Depicted areas of precipitation are currently on the modest to moderate side given track/moisture, but ample upper support and favored terrain lift may lead to locally heavier focus and activity to monitor. The WPC Winter Weather Outlook shows the greatest snow probabilities over Northwest to northern Intermountain/Rockies terrain/mountains. Activity will spread into the Plains later next weekend with system slow progression and cyclogenesis and frontogenesis. 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