Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1103 AM EDT Sun Jul 01 2018 Valid 12Z Wed Jul 04 2018 - 12Z Sun Jul 08 2018 ...Overview and weather threats/highlights... A closed upper high over the Northeast on Wednesday will head westward toward the Rockies by next weekend as upper troughing over Canada dips into New England by Saturday, bringing in cooler temperatures (back near average). Much of the west and central states will see an increase in warmth from Thursday onward. Precipitation will generally focus around the upper high from the Pacific Northwest (in conjunction with an offshore weakening upper low) across the northern tier into the Northeast as well as on the south side of the upper high across the Gulf Coast. By next weekend, precipitation should precede the front southeastward into the Mid-Atlantic and Southeast. ...Guidance evaluation/preferences... In general, the latest model/ensemble guidance remained in excellent agreement with the track of the upper high and good agreement with the features around it. Given some run-to-run shifts in timing/track of these features, a multi-model blend was utilized for days 3-5. Model spread has increased a bit by days 6-7 with respect to how quickly the upper low off the Pacific Northwest ejects eastward. The 00Z/06Z GFS runs have made a significant shift from continuity, showing this energy moving rapidly eastward, nearing Hudson Bay by Sun. Given the amplified flow pattern, and the expected extratropical transition/recurvature of Tropical Storm Prapiroon toward the Aleutians by the middle of the week, would expect increased downstream flow amplification and resultant slower motion across the western CONUS. Thus, leaned away from the GFS by days 6-7 and toward the slower 00Z ECMWF/CMC solutions, with increased weighting of ensembles by next weekend. This maintained good continuity from the previous shift. Ryan/Fracasso WPC medium range forecasts of 500 mb heights, surface systems, weather grids, quantitative precipitation, and winter weather outlook probabilities are found at: http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4