Extended Forecast Discussion NWS Weather Prediction Center College Park MD 315 AM EDT Wed Apr 3 2024 Valid 12Z Sat Apr 06 2024 - 12Z Wed Apr 10 2024 ...Pattern Overview and Guidance/Predictability Assessment... Guidance has been steadfast with development of an omega style blocking pattern over the continental U.S. by later this week as highlighted by Saturday by amplified closed upper troughs over the West and the Northeast that sandwich a central nation upper ridge. However, this pattern is slowly progressive over the weekend and into next week as the Northeast low shifts eastward to off the Canadian Maritimes and the system over the West lifts northeastward into the north-central U.S., kicked out as new closed upper troughing digs down the West Coast and into the Southwest. Model and ensemble solutions remain reasonably well clustered with this overall, bolstering forecast confidence. Even so, there are still varied depictions of complicated system interactions into next week out through the central U.S. that have implications for fronts, precipitation, and cloud cover, which could affect viewing conditions for the total solar eclipse on Monday. Forecast spread is also more apparent next week with the ultimate ejection timing into the Plains of the kicker closed low set to dig into the Southwest and late period emerging convection/rainfall potential. The WPC forecast was mainly derived from a multi-model blend of the 18 UTC GFS and 12 UTC ECMWF/CMC/UKMET for maximum system detail consistent with above normal predictability this weekend into Monday. Opted to increasingly transiiton toward the ECMWF ensemble mean early-mid next week amid growing uncertainties, but with purpose to best maintain trends into evolution of an amplified west-central U.S. upper trough and east-central nation upper ridge pattern. ...Weather/Hazards Highlights... The potent closed upper low and coastal storm will shift increasingly offshore New England this weekend, slowly ending cooled/windy conditions and lingering wrapback snows with renewed maritime and Canadian Maritime focus. Meanwhile, unsettled and wintry conditions spread over the West/Southwest will gradually ease into the weekend as a leading amplified upper trough/closed low and associated/wavy surface frontal system lifts across the snowy/wet Rocky states and across the Plains to the Midwest where a slow moving axis of precipitation could foster some local heavier convective downpours. SPC also indicated a Severe Weather threat this weekend over the southern Plains with system approach/instability. Complicated and uncertain fronto/cyclo genesis transitions should act to focus a lead enhanced moisture conduit from the south-central U.S. to the north- central Rockies/Plains then Midwest. Behind the system, high winds and critical fire danger will be possible in the southern and central Plains as humidity drops and winds increase. Upstream, a renewal of mainly light to moderate precipitation is possible along the West Coast early next week as a new Pacific upper trough/closed low digs down and then into an unsettled Southwest. The focus for precipitation will then shift into the south-central U.S., perhaps into Tuesday and next Wednesday as Gulf inflow may be signifciantly re-energized with eventual system ejection to monitor. Heavy rainfall may lead to flash flooding concerns for the southern Plains and lower Mississippi Valley in this time frame to monitor. 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