Extended Forecast Discussion NWS Weather Prediction Center College Park MD 209 PM EDT Wed Jul 13 2022 Valid 12Z Sat Jul 16 2022 - 12Z Wed Jul 20 2022 ...Heat Threat to loom over much of the Western and Central U.S.... ...Heavy Rainfall threat for the central Gulf Coast states and Southeast... ...Guidance Evaluation/Predictability Assessment... The overall synoptic pattern across the lower 48 is standard with ridging over the southern tier states and waves of low pressure swinging across the central and northern tier. A Euro-centric/Canadian blend was favored throughout the period due to disparities between the GFS and the other deterministic models. A mainly 00z EC/UK blend was utilized on day 3 due to attempts by the 00z CMC and the last several runs of the GFS to spin up a closed surface wave over the Southeast coast. A more averaged blend of the 00z EC/CMC/UK was used to capture troughing in the East without the presence of a pronounced upper-ridge which the 06z GFS signaled on days 4 and 5. The 00z suite of the ensemble means were introduced on day 6 and continued through day 7 because they captured the overall pattern very well with troughing in the Northwest and Northeast/Mid-Atlantic as well as ridging across the South. ...Overview and Weather/Hazards Highlights... A hot upper high/ridge will settle westward into the Four Corners to support above normal temperatures across much of the West, but also with widespread heat to persist downstream across the central U.S. as ridging/heights build over the region. In this pattern, modest monsoonal moisture flow across the Southwest into the Great Basin/Rockies under the upper ridge may offer daily chances for showers with some locally heavier downpours with slowed cell motions. Meanwhile, a series of uncertain impulses will round the top of the ridge to periodically focus strong but more progressive convection out from the north-central U.S./Midwest. Upper trough positions will sandwich the upper ridge, both into the Pacific Northwest where rainfall chances are limited and also the East where fronts will focus some rain and thunderstorms. Moisture will pool from the eastern Mid-Atlantic to the Southeast and Gulf Coast states. Possible sub-tropical/tropical interaction over the northern the Gulf of Mexico may support heavy rain potential into the central Gulf Coast and vicinity as any slow-moving and repeat cells with very heavy downpours would still lead to local runoff issues. Additional tropical influences also remain in play up the Atlantic coast of Florida to the coastal Carolinas this weekend as the lifting of energy and deepened moisture could act to more deeply fuel a rainfall/runoff threat across this area. Kebede/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