Extended Forecast Discussion NWS Weather Prediction Center College Park MD 414 PM EDT Mon Jul 06 2020 Valid 12Z Thu Jul 09 2020 - 12Z Mon Jul 13 2020 ...Guidance/Predictability Assessment... Smaller scale differences remain with respect to an Eastern Seaboard coastal low currently being monitored by NHC. The 06z GFS was noticeably faster/more progressive with the low, but the latest 12z run this morning looked better. WPC favors a blend of the ECMWF with the CMC which are closer and more within the spread of the ensembles. The UKMET also lies within the spread, though is stronger (likely owing to a more offshore track) and while it is not out of realm of possibilities, opted to lean closer to continuity and not include in todays blend. Elsewhere across the nation, there is above average consensus on reinforced troughing across the Eastern U.S. late in the period along with troughing moving into the Western U.S.. The blend for today from WPC leaned heavily on the ECMWF days 3-5, with smaller contributions from the 00z CMC and ensemble means. For 6-7, leaned more on the ensemble means to mitigate the less predictable detail differences at the longer range time scale. This maintains very good continuity with the previous WPC forecast. ...Weather Pattern/Hazard Highlights... Upper trough energies will periodically work inland over an unsettled Northwestern U.S. and western Canada. A steady stream of ejecting impulses then progress downstream over southern Canada and the U.S. northern tier. This will force moderating fronts over the broad region and spawn some strong to severe thunderstorms. Convective rainfall potential may focus from the Northern Plains southeastward across the Midwest. Triple digits maximum temperatures (approaching/exceeding some heat records) are likely from the Desert Southwest/southern Great Basin to the south-central Plains, with heat indices making it feel closer to 115 in some places. Hot and humid weather also stretches into the Midwest and Eastern states as well. A heavy rain/weather threat is also expected to lift from the Southeast to coastal Mid-Atlantic and New England contingent on upper support/coastal low development. The best consensus at this time keeps the heaviest rainfall offshore, but this could shift closer to the coast dependent on surface low track/possible tropical development. Santorelli/Schichtel Hazards: - Heavy rain possible from eastern Kansas to western Missouri, as well as near the North Carolina coast, Thu-Fri, Jul 9-Jul 10. - Flooding possible across portions of the northern Plains. - Flooding occurring or imminent over portions of central North Dakota. - Excessive heat across portions of the southern Plains to the lower Mississippi Valley, Fri-Sun, Jul 10-Jul 12. - Much above normal temperatures across portions of the southern High Plains, Sat-Mon, Jul 11-Jul 13. - Much above normal temperatures across portions of northern New England and into the Great Lakes, Thu-Fri, Jul 9-Jul 10. 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