Extended Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EDT Tue Jul 2 2024 Valid 12Z Fri Jul 5 2024 - 12Z Tue Jul 9 2024 ***Major heatwave expected for the lower elevations of California and the Desert Southwest next week, and Beryl eventually headed for the Western Gulf*** ...Overview... The main thing making weather headlines during this forecast period will the intense and prolonged heatwave encompassing much 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, and 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. The track of Hurricane Beryl is expected to enter the Bay of Campeche and the Western Gulf by Saturday with rainfall chances increasing for portions of southern Texas by the weekend. ...Guidance/Predictability Assessment... The 00Z model guidance suite indicates good overall synoptic scale agreement across the Continental U.S. to close out the work week, and better agreement on the massive upper ridge building over the West Coast, potentially reaching 600dm. The guidance suggests this ridge should slowly move east over the southern Intermountain West by next Tuesday/Wednesday. Meanwhile, a general trough axis situated over the north-central U.S. should be anchored in place by another ridge axis over the western Atlantic Ocean. A general deterministic model blend sufficed as a good starting point in the forecast process for Friday/Saturday, and then increased the ensemble means to about 40% by next Tuesday. The latest forecast from the National Hurricane Center has Hurricane Beryl reaching the Yucatan Peninsula around Friday morning, and then emerging over the Bay of Campeche by Saturday, followed by more of a northwestward turn. There has been a recent trend in the guidance for a more northward track by the time it enters the western Gulf, which could result in deteriorating weather conditions for southern Texas. The trough over the Central U.S. will be a big factor in determining the eventual track. Beryl's track will continue to be closely monitored over the next several days, and the NHC has additional information pertaining to this. ...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 the developing 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, and a Marginal Risk area is also valid here for Friday. This has trended more southward compared to yesterday's forecast. Looking ahead to Saturday, there is enough of a model signal to support a planned Marginal Risk area for portions of the Mid-Atlantic, where some slow moving thunderstorms are likely to develop in the vicinity of a slow moving frontal boundary. Some of the outer rain bands of Beryl could be approaching southern Texas by late Saturday and into early Sunday, but generally not expected to be heavy enough by that time to warrant any risk areas. This could change going into Sunday, especially if the track trends farther north in later forecast updates, so stay tuned! 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 and into the Arizona Deserts with widespread 105-115 degree readings likely, and locally higher for the normally warmer locations. Daily temperatures records may be tied or broken in many cases. The heat likely expands 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. 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