Extended Forecast Discussion NWS Weather Prediction Center College Park MD 252 AM EDT Sun Jul 10 2022 Valid 12Z Wed Jul 13 2022 - 12Z Sun Jul 17 2022 ...Excessive rainfall threat for the central Gulf Coast states... ...Guidance Evaluation/Predictability Assessment... The 18 UTC GFS and 12 UTC ECMWF/ECMWF ensemble mean seem to offer guidance solutions best clustered with WPC continuity across the lower 48 and also with latest NHC Gulf of Mexico and western Atlantic system monitorring details into Wednesday/Thursday. A blend seems reasonable and shows decent detail consistent with flow with above normal predictability. The 00 UTC UKMET/Canadian now better support this solution. Switched to a blend of the still compatible GFS and ECMWF ensemble mean and National Blend of Models into later week and next weekend in a period when recent ECMWF runs have seemed to offer less supported subtropical feature depictions. Latest 00 UTC guidance has also trended to prolong the central Gulf coast heavy rainfall threat through these latter time frames as the supporting system becomes more separated from the steering flow. ...Overview and Weather/Hazards Highlights... A main upper high/ridge will settle westward into Four Corners this week to support above normal temperatures across much of the West, but the most anomalous heat is forecast to spread downstream across the north-central U.S. as ridging/heights build over the region. In this pattern, monsoonal moisture flow across the Southwest into the Great Basin/Rockies may offer daily chances for showers with some locally heavier downpours. Meanwhile, a series of uncertain impulses will round the top of the ridge to periodically focus strong convection locally over the north-central Plains/Upper Midwest. Upper trough positions will sandwich the upper ridge both off the Pacific Northwest where rainfall chances are limited and also the East where fronts will focus rain and thunderstorms. Moisture will pool from the eastern Mid-Atlantic to the Southeast and Gulf Coast states near a wavy stalled lead front. Interaction with a sub-tropicical disturbance may in particular support heavy rain potential near the central Gulf Coast. This could focus slow-moving/repeat cells with very heavy downpours leading to a local runoff issues, so a "slight" risk area was added to the experimental WPC medium range Excessive Rainfall Outlook through midweek. 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