Extended Forecast Discussion NWS Weather Prediction Center College Park MD 249 AM EDT Tue Jun 28 2022 Valid 12Z Fri Jul 01 2022 - 12Z Tue Jul 05 2022 ...Weather Pattern Overview... A relatively flat upper level flow pattern in place over the northern tier of the nation this week may amplify over the holiday weekend as a closed low/trough develops just offshore the Pacific NW/West Coast and as a hot ridge lingering over the U.S. southern tier builds over the north-central states. This scenario may also support holiday amplification of a broad trough over the Northeast U.S. underneath a deep Hudson Bay closed vortex. NHC is also monitoring a tropical wave/disturbance over the northern Gulf of Mexico, riding underneath the ridge toward Texas. ...Guidance Evaluation/Predictability Assessment... The 12 UTC model and ensemble suite was in very good synoptic scale agreement through medium range time scales. The WPC medium range product suite was primarily derived from a composite blend of best clustered guidance from the 12 UTC GFS/ECMWF and GEFS/ECMWF ensemble means. This maintains excellent overall WPC product continuity, and individual system forecast differences remain well mitigated by the blend process. The 18 UTC GFS showed more flow amplification at longer time frames, but with less ensemble support. 00 UTC guidance trended more in line. ...Sensible Weather and Potential Hazards... A lingering stationary front along the Gulf Coast and southeast coastal U.S. will likely promote the development of scattered to numerous showers and storms for the end of the work week. There may be an enhanced area of heavier rainfall across portions of Texas based on recent Canadian/ECMWF runs, and this will likely be dependent on any organized low pressure areas that develop over the western Gulf of Mexico as per NHC. Farther north, a corridor of showers and storms is likely along and ahead of a cold front that will be slowly tracking towards the southeast across the Midwest, Ohio Valley, and Great Lakes regions going into the weekend. The trailing front could pool deep Gulf/tropical moisture from the Plains to the Mid-Atlantic over the holiday weekend as shortwaves round the northern periphery of the upper ridge. Monsoonal moisture over the Four Corners region may also result in scattered areas of heavier rainfall with impulses and moisture lifting on the western periphery of the upper ridge. , In terms of temperatures, expect readings to be running up to 10 degrees above normal ahead of the front from the Upper Midwest to the Northeast U.S. to close out the week, followed by seasonal temperatures going into the Saturday to Monday time period. Heat is likely to build again across the central and northern Plains by next Monday in response to the building upper ridge, and slightly cooler conditions for the West Coast region that may include some July rainfall over the Northwest with height falls/system approach. Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, experimental excessive rainfall outlook, 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml