Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1200 PM EDT Sun Jul 28 2019 Valid 12Z Wed Jul 31 2019 - 12Z Sun Aug 04 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 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 struggled with Pacific flow including the timing/track of a pair of midweek then later week systems. Confidence remains low with these systems, but about average elsewhere. A composite blend of the 06 UTC GFS and 00 UTC ECMWF/UKMET seems to offer a decent flow/system depiction Wed-Fri. opted for a blend of the compatable 06 UTC GEFS mean and 00 UTC ECMWF ensemble mean along with WPC continuity through next weekend amid growing forecast spread with embedded system amplitude, timing and local convective/MCS focus. ...Weather Highlights/Threats... Below average temperatures in AZ/UT due to monsoonal moisture (and in increase in clouds/showers/storms) will moderate a bit with time as the upper high drifts just enough eastward to focus rainfall over CO/NM next weekend. Overtop, coastal Washington may see an increased rain chance into later week on the uncertain edge of lifting Pacific energies. 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 as fueled by pooled moisture and instability under the mean trough aloft and a series of digging/passing impulses aloft. East of Florida, an emerging tropical wave may bring increased rainfall to the Bahamas and perhaps into eastern North Carolina next weekend. 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