Extended Forecast Discussion NWS Weather Prediction Center College Park MD 308 PM EDT Tue Jul 2 2024 Valid 12Z Fri Jul 05 2024 - 12Z Tue Jul 09 2024 ...A major heatwave expected to persist for the West Coast through early next week with excessive heat likely for the interior lower elevations of California and the Desert Southwest... ...Beryl could be in the vicinity of Texas Gulf coast early next week... ...Overview... The main thing making weather headlines during this forecast period will be a prolonged heatwave encompassing much of the West Coast with the most intense heat focusing along the Central Valley of California and extending into the lower elevations of the Desert Southwest. Hot and humid conditions will also continue for much of the southern states and extending to the East Coast. A low pressure system is forecast to cross the Upper Midwest and bring a round of heavy rain and storms to the Great Lakes on Friday, with additional storms near the trailing frontal boundary across portions of the Southern Plains and extending east to the Ohio Valley and the Mid-Atlantic region. Meanwhile, the National Hurricane Center is forecasting tropical cyclone Beryl to reach southern Texas by early next week. ...Guidance/Predictability Assessment... Model guidance this morning continues to indicate good agreement that mean troughing will persist over the mid-section of the country through the medium-range period while a warm ridge will persist and nudge farther inland into the western U.S. The model consensus has been nudging the mean trough over the mid-section country southward. This has resulted in a subtle southward shift of the track of an occluded low across the Great Lakes, as well as a southward dip of the trailing cold front over the southern Plains. The southward dip of the mean trough has also lead to a slightly more amplified upper-level pattern across the U.S., as the upper ridge over the western U.S. and off the East Coast remain at similar intensity. The southward dip of the mean trough also has implication regarding how far north tropical cyclone Beryl will eventually track toward the western Gulf Coast region. Subtle mutual interaction between the mean trough and the circulation of Beryl together with the uncertain distance between the two systems would introduce a higher degree of forecast uncertainty over the vicinity of southern Texas, western Gulf Coast, and northeastern Mexico for early next week. ...Weather/Hazards Highlights... Heavy rain with embedded thunderstorms are likely to continue across northern Wisconsin and into the Upper Peninsula of Michigan going into Friday as an occluded surface low tracks across the region, and a Marginal Risk will remain there for the Day 4 period. Farther south, a corridor of heavy showers and storms is likely from northern Texas to the Tennessee River Valley ahead of a cold front. The western extent of the Marginal Risk area over the southern Plains for Friday has been trimmed off due to the aforementioned southward dip of the front. Looking ahead to Saturday, there is enough of a model signal to maintain the Marginal Risk area for portions of the Mid-Atlantic, where some strong thunderstorms with heavy rain rates could develop quickly in the vicinity of the cold front with its forward motion slowing down. Some of the outer rain bands of Beryl could be approaching southern Texas by late Saturday and into early Sunday, but the intensity and location of Beryl remain uncertain at this point. It will continue to remain hot and humid across Texas and extending eastward across the Deep South and into the Southeast for the end of the week and into next weekend, with highs in the middle to upper 90s and dewpoints well into the 70s. It will also be getting very hot for the inland lower elevations of California with widespread 105-115 degree readings likely. Readings could reach 120 degrees at the hottest locations in the Desert Southwest. Daily temperatures records may be tied or broken in many cases. The heat will likely expand across inland portions of Washington, Oregon, and much of the Intermountain West by the Sunday-Tuesday time period, with 100+ degree highs likely for the lower valley locations. Kong/Hamrick 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 forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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 https://www.wpc.ncep.noaa.gov/#page=ovw