Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Mon Apr 1 2024 Valid 12Z Thu Apr 04 2024 - 12Z Mon Apr 08 2024 ...Major New England Coastal Storm with maritime hazards and high wind/coastal flooding along with Northeast heavy snow into Thursday... ...Widespread precipitation/cooling pattern for the West into late week to work into the Central U.S. through next weekend... ...Guidance/Predictability Assessment... The 12 UTC GFS/ECMWF/UKMET model and multi-center ensemble solutions seem best clustered with the mid-larger scale flow evolution and main flow embedded weather systems slated to impact the lower 48 and vicinity this week in a stormy pattern with generally 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 into the weekend given best ensemble support and continuity. This blend tends to provide decent detail while reasonably mitigating guidance differences consistent with individual predictability. The latest 00 UTC model and ensemble solutions remain generally in line. WPC product continuity is also well maintained with this forecast plan. ...Pattern Overview and Weather/Hazards Highlights... A major Nor'easter will present a threat for eastern New England coastal flooding and significant wrap-back early spring heavy snows across the Northeast thay will persist Thursday with potent closed upper trough rotation 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 rain. The heaviest of the wet snow is expected to fall across the higher elevations of the interior Northeast, with some light snow lingering into Friday. Models and ensembles meanwhile show a highly amplified upper pattern also upstream across the U.S. later week with a ridge over the central U.S. and potent upper troughing digging down the West Coast. This strongly amplifying upper trough/closed low and leading and wavy cold front/secondary Canadian cold surge digging into the West will act to cool temperatures. This may risk record cold maximum temperatures through southern California. The spread of enhanced precipitation and windy/unsettled flow will include Pacific Northwest through California rains closer to coastal areas along with a prolonged period favorable for terrain/mountain snows increasingly inland across much of the West later week into the weekend as main upper trough energy and height falls shift robustly inland. The energy will eject northeastward over the central U.S. Sunday into Monday along with an associated lead return conduit of moisture and clouds. This will initiate and spread organized moderate precipitation across the broad region with cyclogenesis/frontogenesis as new Pacific upper trough system energies again dig back down over the West Coast. 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