Extended Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Mon Jun 27 2022 Valid 12Z Thu Jun 30 2022 - 12Z Mon Jul 04 2022 ...Weather Pattern Overview... A relatively zonal 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 near 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 monitoring a tropical wave/disturbance over the northern Gulf of Mexico, riding underneath the ridge. ...Guidance Evaluation/Predictability Assessment... The 00/06/12 UTC model and ensemble guidance suite remain in very good synoptic scale agreement through medium range time scales. The WPC medium range product suite was primarily derived from a model and supporting ensemble mean composite blend days 3-7 (Thursday-July 4th). This maintains good overall WPC product continuity, and individual system forecast differences seem well mitigated by the blend process. Potential tropical influences into Texas later this week and the subsequent deep moisture feed/QPF threat inland into several frontal systems downstream remain less certain. ...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. Hamrick/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 Hazards: - Heavy rain across portions of southern and eastern Texas, Thu-Sat, Jun 30-Jul 2. - Heavy rain across portions of the central Plains and Middle Mississippi Valley, Fri-Sat, Jul 1-Jul 2. - Heavy rain across portions of the Southern Rockies and the Southwest, Thu-Mon, Jun 30-Jul 4. - Flooding occurring or imminent across portions of the Upper Mississippi Valley and the Northern Plains. - Flooding likely across portions of the Middle Mississippi Valley and the Northern Great Basin. - Excessive heat across portions of the north-central Plains, Mon, Jul 4. 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