Extended Forecast Discussion NWS Weather Prediction Center College Park MD 430 PM EDT Mon Jul 15 2019 Valid 12Z Thu Jul 18 2019 - 12Z Mon Jul 22 2019 ...Tropical Depression Barry to further weaken but still fuel Northeast heavy rains Thursday as a Post-Tropical Remnant Low before exiting to Canadian Maritimes Friday... ...Guidance/Predictability Assessment... The Weather Prediction Center assumed responsibility from the National Hurricane Center to issue advisories on inland Barry until the surface circlulation has dissipated and an associated flash flooding threat diminishes. Tropical Depression Barry is expected to become a Post-Tropical Remnant Low later today and deepened moisture is expected to fuel some lingering heavy rains Thursday across the Northeast before exiting into the Canadian Maritimes Friday. The WPC medium range product suite was prmarily derived from a composite blend of well clustered guidance from the 00 UTC NAEFS/ECMWF ensemble means. The 00 UTC ECMWF and GEFS mean also cluster reasonably well with this preferred solution that offers a fairly well established larger scale pattern with much less certainty with embedded smaller scale impulses and local convective focus. This maintains good WPC continuity. This blend did not include the 00 and 06 UTC GFS that produce an outlier solution with more mid-upper level trough amplification and significantly more lower atmosheric cooling from the Rockies to the Midwest Saturday-next Monday. Downplayed this scenario given continuity and strength of the hot precursor ridge building up into this region. ...Overview and Weather Highlights/Threats... Tropical moisture from the remnants of Barry will spread across the northern Mid-Atlantic and Northeast through Thursday as the leading edge of the front tracks offshore. Areas of localized heavy rain may increase the threat for flash flooding, especially in areas of higher terrain and reduced FFG. A quasi-zonal flow pattern will develop across the northern-tier of the U.S. Throughout this coming week a series of hard to time disturbances will pass through southern Canada and through the northern states. Showers and thunderstorms capable of producing locally heavy convection/MCS activity will sporadically develop and propagate within a wavy frontal/baroclinic zone across the Northern Plains, Upper Mississippi Valley and into the Upper Great Lakes region, then into the Lower Great Lakes and Northeast. There will likely be multiple periods where rainfall amounts/or rates become locally excessive as the moisture and instability pooling frontal boundary stalls over the region. There is quite a range for QPF within the global models. With a less than average confidence on the exact timing and placement of any individual feature, opted to remain on the near the middle/lower end of the output with this issuance. The regions with the best chances for higher precipitation is the Upper Mississippi Valley and Great Lakes Saturday through Sunday. Summertime ridging over southern and central portions of the U.S. will spread over much of the Southwest and Southern and Central Rockies; keeping temperatures near or above seasonal average. Many locations are expected to be warmer and drier through this the extended period. Some locations may tie or set new daily high minimum records. Heat indices will be around 105 to 115F, which may lead to some future issuance of heat advisories. Schichtel Hazards: - Heavy rain across portions of the Upper Mississippi Valley and the Northern Plains, Sun, Jul 21. - Flooding possible across portions of the Upper Mississippi Valley. - Flooding occurring or imminent across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Ohio Valley. - Flooding likely across portions of the Central Plains, the Middle Mississippi Valley, the Lower Mississippi Valley, and the Northern Plains. - Excessive heat across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Thu-Sat, Jul 18-Jul 20. - Excessive heat across portions of the Southeast, the Mid-Atlantic, the Northeast, and the Central Appalachians, Fri-Sun, Jul 19-Jul 21. 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