Extended Forecast Discussion NWS Weather Prediction Center College Park MD 232 PM EDT Thu Jul 4 2024 Valid 12Z Sun Jul 07 2024 - 12Z Thu Jul 11 2024 ***Dangerous and major heatwave continues for the lower elevations of California and the Desert Southwest into next week, and Beryl approaches southern Texas Sunday into Monday*** ...Overview... The dangerous and major heatwave will continue to affect much of California and extending into the lower elevations of the Desert Southwest and Intermountain West through the middle of next week. Meanwhile, attention turns to the track of Hurricane Beryl as it crosses through the Yucatan Peninsula and heads toward South Texas late Sunday into Monday. Meanwhile, a quasi-stationary front across the eastern U.S. will serve as a focusing mechanism for showers and storms south of the boundary across the Deep South and Southeast/Mid-Atlantic region, and this will be ahead of an upper level trough that is expected to build across the Northern Plains and Upper Midwest. Hot and humid conditions will also continue for much of the southern states and extending to the East Coast. ...Guidance/Predictability Assessment... For the synoptic pattern, there was relatively good agreement across the latest deterministic and ensemble guidance. The 500 mb heights are expected to feature a rather persistent and building upper ridge over the Desert Southwest through at least the middle of next week. By Day 7, there was enough model agreement to show a passing shortwave and frontal boundary into the far Pacific Northwest. Meanwhile, downstream into the Central U.S. there is good predictability for troughing over the Central Plains, Upper Midwest, and Great Lakes with a passing shortwave trough helping to reinforce the trough early to mid week next week. Finally, ridging will remain in place across the Southeast U.S., extending along the coastal areas into the Mid Atlantic. Finally, the latest NHC track for Beryl brings the storm center near the Mexico/Texas border early Monday morning. The guidance lies just to the north of model consensus as it makes landfall and then from there, uncertainty builds with the possible interaction with a digging frontal boundary into the Plains, helping to recurve the system further into Texas or alternatively, the system stays south along the Mexico/U.S. border before dissipating. For now, the official NHC track takes the center along the border. The WPC QPF favored a blend of the NBM to start, followed by increases using the latest ensemble bias corrected QPF as well as some inclusion of the ECMWF and GFS for Beryl, to help increase rainfall amounts across portions of South Texas and points westward. 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... For Beryl, WPC is maintaining Slight Risks on the Day 4 and Day 5 Excessive Rainfall Outlooks for South Texas. A lot depends on the track and speed of the system, but potential exists for several inches over the course of 2 days for far South Texas and possible future upgrades across far South Texas along the U.S. border. Further north into central/east central Texas, there is less confidence on how Beryl interacts with an approaching frontal boundary but potential exists for organized convection capable of producing heavy rainfall. Meanwhile, heavy rainfall and flash flooding will be possible on Day 4 across portions of Oklahoma and Kansas with a shortwave trough and frontal boundary drop through the region. Scattered showers and storms are likely to persist across much of the Gulf Coast, Deep South, and the East Coast states going into the middle of next week with a moist and unstable airmass remaining in place. Major heat will continue to make weather headlines for the West Coast states, with 100+ degree high temperatures extending to northern Washington for the entire forecast period. Highs will likely reach the 110s for the lower elevations of inland California, southern Nevada, and southern Arizona, with some 120s possible for the normally hotter locations. Some of this extreme heat will likely expand eastward to include much of the Intermountain West, including Utah and Idaho where some triple digits readings are expected. Numerous daily records are likely to be established during this prolonged and dangerous heat event, with major to extreme heat stress conditions. Even Wyoming and Montana get above average temperatures by next Wednesday/Thursday as the upper ridge slowly moves inland across the Rockies. Numerous daily record high temperatures are forecast across much of this region. Elsewhere, seasonal levels of heat and humidity can be expected most days for the southern and eastern parts of the country, although there will likely be some days that reach heat advisory criteria in some areas. Hamrick/Taylor 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