Extended Forecast Discussion NWS Weather Prediction Center College Park MD 110 PM EDT Sat Jul 25 2020 Valid 12Z Tue Jul 28 2020 - 12Z Sat Aug 01 2020 ...Overview... Summer heat with a subtropical high centered over the Southern High Plains in the short term is forecast to slowly retrograde toward the Four Corners region through the medium range period. Meanwhile, an upper low in east-central Canada should spread troughing into the Midwest/Great Lakes and then into the Northeast/Mid-Atlantic by midweek, pushing a cold front through those areas. Unsettling lowering heights/frontal passages next week into the Northwest will replace short term upper ridging as troughing establishes off the West Coast. ...Weather/Hazard Highlights... Hurricane Hanna will likely have dissipated over a wet northern Mexico by the start of the medium range period, although lingering tropical moisture and instability along the Gulf Coast may result in periods of locally heavy rainfall into Wednesday. To the north, a cold front should push across the Northeast on Tuesday, while becoming stationary across the Tennessee/mid-Mississippi Valleys and back into the Central Plains through midweek. Rain and thunderstorms should focus along this boundary with locally heavy rainfall possible, aided by Southwestern U.S. monsoonal moisture. Upper level energy rounding the top of the Southern tier ridge looks to settle into the Midwest states by Thursday, with several pieces of guidance indicating the potential for additional rounds of organized rainfall and thunderstorms from the middle Mississippi Valley into the Tennessee and Ohio Valleys Wednesday into Friday. The cold front across the Northeast may become stationary along the Mid-Atlantic coast bringing a chance for moderate to locally heavy rainfall to parts of the Carolina Coasts through Friday as well. Above normal temperatures (+5 to +10 degrees above average) initially across parts of the Northwest and East Coast on Tuesday should moderate back towards normal the remainder of the week. Gulf Coast to Southern Plains states begin the period below normal with abundant cloud cover/moisture, but by the middle of the week should also warm up to near normal. ...Guidance/Predictability Assessment... Guidance shows relatively good agreement on the overall large scale pattern, but more than expected variances in the smaller scale and less predictable features including QPF. Accordingly, the WPC medium range product suite was primarily derived from a composite blend of the relatively more compatible 06 UTC GEFS mean and 00 UTC ECMWF ensemble mean along with the 13 UTC National Blend of Models and a good dose of WPC continuity. Schichtel/Santorelli 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