Extended Forecast Discussion NWS Weather Prediction Center College Park MD 254 AM EDT Mon Apr 11 2022 Valid 12Z Thu Apr 14 2022 - 12Z Mon Apr 18 2022 ...Overview... A strong springtime low pressure system will be exiting the Upper Midwest as the period begins Thursday, as its attendant cold front slides through the East. After Thursday/day 3, the pattern finally appears to deamplify somewhat as a weaker shortwave/trough moves into the West around Friday-Saturday. Guidance shows this trough moving eastward with time eventually into the central Plains where it could induce another low pressure system across the Midwest next Monday. This could bring another round of precipitation into the northern and eastern part of the country early next week, although there's still plenty of uncertainty with respect to the details. ...Guidance Evaluation/Predictability Assessment... The latest models and ensembles finally seem to show some decent agreement on the large scale evolution of the departing deep upper low into Eastern Canada Thursday-Friday, which looks to meander/weaken there as it gets blocked by amplified western Atlantic ridging. Models show varying degrees of uncertainty regarding shortwave energy rounding the base of this through the Southeast, with secondary low pressure developing along the cold front off the Northeast Coast next Friday. The ECMWF has both been most consistent and strongest with this, which of course has implications for how much precipitation lingers across the Southeast/East Coast into next weekend. A general deterministic model blend (with slight weighting towards the ECMWF for continuity reasons) seemed to provide a good starting point for days 3-4. Out West, the models continue to show a lot of uncertainty surrounding the next trough through the region. There's good agreement on low pressure present near the coast on day 3, but after that questions begin to arise regarding strength and timing of the main trough axis through the Northwest. The ECMWF and UKMET are strongest/most amplified with this trough and also downstream ridging across the north-central U.S.. By day 6, the latest runs of the ECMWF and GFS show pretty good agreement on timing of the wave into the Central U.S., but poor run to run continuity on this feature which tempers confidence quite a bit. The CMC is entirely too weak/flat with this system and was not included in the blend after day 4. The ECMWF continues to be notably stronger with the wave into the Midwest on Monday/day 7, indicating a deep closed low and well defined low pressure system at the surface. Prefer a blend towards the better agreeable (and weaker) ensemble means for the latter periods to help mitigate the harder to resolve differences. ...Weather Highlights/Threats... Some lingering snows are possible across the Upper Midwest at the start of Thursday, but the heaviest should be rapidly coming to an end as the deep low departs into Canada. Gusty winds are likely to continue into Friday though creating blowing and drifting of snow and possible hazardous travel conditions. Moderate to locally heavy rainfall should be moving through the East ahead of the attendant cold front on Thursday into Friday, with the best chance for heavier totals across parts of the Southeast where the better moisture and instability will be present. Rainfall across the Southeast could linger into the weekend as the western edge of the boundary tries to lift north as a warm front and weaken across the Southeast. Out West, moderate to heavy rain/mountain snows are possible across parts of California/Oregon with the next low pressure system Thursday-Friday. Moisture should spread east into the Intermountain West and northern Plains next weekend. Significant uncertainty regarding low pressure into the Midwest next week, but the latest guidance suggests decent probability for another round of precipitation to affect the northern and eastern states early next week. The core of the below normal temperatures are likely across the northern High Plains into early next week, with daytime highs around 20-30 degrees below normal possible. Out West, below normal temperatures should moderate back towards normal later in the period as ridging tries to build over the region. Above normal temperatures along the Eastern Seaboard initially should trend back towards normal next weekend. Below normal temperatures will spread south and east next Sunday-Monday into the Midwest with some readings 10-20F possible. Santorelli 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