Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1200 PM EDT Tue Jul 03 2018 Valid 12Z Fri Jul 06 2018 - 12Z Tue Jul 10 2018 ...Overview and weather threats/highlights... Model guidance this morning shows excellent agreement that the strong subtropical high currently dominating much of the U.S. will temporarily give way to a cold front moving down into the East Coast Friday into the weekend. This will offer relief from the current heat wave especially for the Great Lakes and the Northeast this weekend. Meanwhile, models are unanimous in building the subtropical high will building westward into the western U.S. as a closed low just off the West Coast lifts towards British Columbia. This will keep the presence of a positively-tilted trough around the Pacific Northwest into early next week. Models are also bringing the next upper-level trough from the Northeast Pacific towards western Canada early next week with noticeable differences in speeds and amplitudes as it attempts to override the top of the subtropical high over the western U.S. Teleconnection/climatology supports a western U.S. ridge with a Northeast U.S. trough. The 00Z EC mean and the 06Z GEFS are in agreement with this scenario. Meanwhile. models are indicating tropical moisture associated with weak disturbances will move westward along the Gulf Coast this weekend into early next week. This will keep a good chance of showers and thunderstorms through the region into next Tuesday along with cooler than normal temperatures. As the subtropical high builds westward, heat is expected to intensify over the interior western U.S. where triple-digit temperatures appear likely from the Great Basin into interior California. A weak cold front should bring slightly cooler air into the northern Rockies by this weekend. ...Guidance evaluation/preferences... The morning WPC grid package is a general consensus of the 00Z ECMWF, 06Z GFS, and the 00Z NAEFS with more of their ensemble means incorporated on Days 6 and 7. The 00Z EC mean was not included due to communication problems. Kong 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