Extended Forecast Discussion NWS Weather Prediction Center College Park MD 210 AM EDT Mon Jul 29 2019 Valid 12Z Thu Aug 01 2019 - 12Z Mon Aug 05 2019 ...Overview and Guidance/Predictability Assessment... The medium range North American upper flow pattern will be driven by a closed high over the Four Corners as well as upstream over southern Alaska. This favors positively-tilted (and flattening) troughing over the northeastern Pacific into WA/OR and also downstream over the east-central U.S. underneath more dynamic eastern Canadian troughing. Models/ensembles have shown a bit of convergence with respect to incoming/evolving Pacific flow but still diverge after about Friday. Confidence remains low there but about average elsewhere. A composite blend of the GFS/ECMWF/UKMET/Canadian seemed to offer a good starting point Thu-Fri. GFS/ECMWF and their ensemble means were fairly close thereafter such that an uneven blend weighted a bit more toward the ECMWF provided a reasonable consensus base in light of uncertainty. ...Weather Highlights/Threats... Below average temperatures in AZ/UT due to monsoonal moisture (and an abundance of clouds/showers/storms) will moderate with time as the upper high drifts just enough eastward to focus rainfall over CO/NM this coming weekend into Monday. Coastal Washington may flirt with some mainly offshore rain as a cold front moves inland but most of the dynamics lift into Canada. Downstream, a wavy frontal boundary draped over the east-central states will be a focus for convective rainfall including some locally heavier downpours/runoff issues through the period. Abundant moisture and modest instability under the mean trough aloft will support less organized precipitation away from the boundary in the Southeast. East of Florida, an emerging tropical wave may bring increased rainfall to parts of the Sunshine State, the Bahamas, and perhaps into the coastal Carolinas. Finally, the High Plains/Upper Midwest will see the Canadian system pull its front eastward along with higher chances of rain/convection Sat-Mon. 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