Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1135 AM EDT Sun Jun 23 2019 Valid 12Z Wed Jun 26 2019 - 12Z Sun Jun 30 2019 ...Overview and Guidance/Predictability Assessment... An anomamously amplified closed upper low/trough is forecast to slowly but steadily move into the Pacific Northwest and then lift into British Columbia later this week. In this pattern, ample height falls dig underneath through an unsettled West as upper ridging builds downstream over the High Plains into the western Great Lakes. Troughing in eastern Canada will likely also dig into the Northeast next weekend as in inverted trough develops along the central Gulf coast and as the upper high settles into AZ/NM. The latest deterministic models still offer a reasonably well-clustered starting point for the Wed-Fri period. Thereafter, switched to a blend of the 06 UTC GFS/GEFS mean and 00 UTC ECMWF/ECMWF ensemble mean which smoothed out smaller scale timing and amplitude differences for the lower 48. ...Weather Highlights/Threats... The amplified upper low/trough will favor cooler than average temperatures in most of the West (especially Pacific Northwest into the Great Basin/Intermountain West) and scattered rain/storms with some very high elevation snow. Temperatures initially 5-15 deg F below average will moderate back toward typical late-June values by next weekend as the upper low moves into Canada. Temperatures in the northern Plains/Upper Midwest will be 5-10 deg F above average (80s and some low 90s), but with a daily risk of showers/storms with locally heavy downpours/cell training as deeper moisture and instability pool in the vicinity of a warm front. The Northeast will see cooler temperatures this week as fronts slip through the region. The Southeast and lower MS Valley/Gulf Coast region will see a daily chance of showers/storms in typical summertime fashion, but that may be enhanced as the upper trough moves westward later week into the weekend over a moistened lower level fetch. Fracasso/Schichtel Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, 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/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml