Extended Forecast Discussion NWS Weather Prediction Center College Park MD 220 AM EDT Wed Jul 31 2019 Valid 12Z Sat Aug 03 2019 - 12Z Wed Aug 07 2019 ...Overview and Guidance/Predictability Assessment... Strong upper ridging over the Gulf of Alaska favors troughing along the Pacific Northwest and through the Great Lakes with weakening ridging over the Four Corners region. The model/ensembles mostly agree on the longwave pattern and a blend of the deterministic models sufficed for the weekend period. This takes a system through central Canada with its attendant fronts astride the central northern tier into the southern Mid-Atlantic. Thereafter, the 18Z GFS and 12Z ECMWF clustered well enough with their ensemble means so that a consensus blend sufficed as a starting point Mon-Tue as the Canadian low progressed into Quebec and the cold front enters the Northeast. By next Wed, spread increases with the evolution/track of the eastern system as recent GFS runs were well north or south of the ECMWF, which was closer to the ensemble mean consensus and was the preferred location. Over Florida, a tropical wave or surface trough will lift northward along then away from the Space/Treasure Coast this weekend and into the stationary boundary to the north. ...Weather Highlights/Threats... Monsoonal moisture will focus rainfall mostly over New Mexico Saturday then into AZ/UT/CO next week. Leftover MCS (uncertain details) may sink through Arkansas early Saturday as it rounds the ridge. Elsewhere, rainfall will follow the front in the north and largely pop up in the afternoon in the Southeast, perhaps enhanced over eastern Florida into the coastal Carolinas as the tropical wave dissipates. Temperatures will be a bit cooler than average over the central states with higher chances of rainfall and clouds. Milder than average temperatures are expected over the Great Lakes and Northeast ahead of the northern tier system. Elsewhere, temperatures will be within a few degrees of typical early August values during the day and near/above average for overnight mins in much of the West. Fracasso 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