Extended Forecast Discussion NWS Weather Prediction Center College Park MD 346 PM EDT Thu Jul 09 2020 Valid 12Z Sun Jul 12 2020 - 12Z Thu Jul 16 2020 ...Guidance/Predictability Assessment... Significant shorter range model differences remain with an Eastern Seaboard coastal low whose potential development is being monitored by NHC. Recent GFS and to a lesser extent GEFS runs have been the most progressive with this low into the Northeast this weekend. Recent UKMET runs have been the most developed. While plausible, the WPC product suite was primarily derived instead from a blend of the 00 UTC ECMWF an ECENS/NAEFS ensemble means, which offers good continuity for this coastal low and also seems to provide a good forecast starting point and continuity for the rest of the contiguous U.S. days 3-7. ...Weather Pattern/Hazard Highlights... Wrapping heavy rains and winds will linger over northern New England Sunday as dependent on the development and track of a current coastal Carolina low being monitored by NHC. An amplified upper trough and wavy/reinforcing cold front settles over the eastern U.S. Sunday/Monday in the wake of this low. This rainfall focusing system may be kicked out Tuesday and usher in hot summertime conditions. The kicker amplified upper trough will work into an unsettled Northwestern U.S. and western Canada by Sunday. This system/height falls will progress steadily downstream over southern Canada and the U.S. northern tier Monday-next Thursday. This will force a moderating leading front over the region and pooling moisture/instability may fuel some strong to severe thunderstorms. Heavy rain potential may focus near the Upper Midwest. Uncertain upper troughing may work back into the Northwest U.S. and western Canada in a week. Meanwhile, triple digits maximum temperatures to approach or exceed heat records are likely from portions of CA and the Southwest/southern Great Basin to the south-central Plains. Schichtel/Ryan 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 Hazards: - Heavy rain across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Mon-Wed, Jul 13-Jul 15. - Flooding occurring or imminent across portions of the Southern Plains and the Northern Plains. - Excessive heat across portions of California and the Southwest, Sun-Mon, Jul 12-Jul 13. - Excessive heat across portions of the Southeast, the Middle/Lower Mississippi Valley, the Central/Southern Plains, and the Tennessee/Ohio Valley, Sun-Thu, Jul 12-Jul 16. 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