Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Fri Jul 5 2024 Valid 12Z Mon Jul 08 2024 - 12Z Fri Jul 12 2024 ...Beryl likely to affect Texas early next week... ...Dangerous heat wave in the West persists into next week... ...Overview... What is currently Hurricane Beryl is forecast to move into far northern Mexico or southern Texas around the time the medium range period begins on Monday, with windy conditions and heavy rainfall. Moisture from Beryl may linger in Texas into midweek as it could interact with a frontal system ahead of an upper-level trough. This trough will gradually move eastward through the period, with scattered storms across the eastern half of the U.S. at times. Meanwhile, a persistent upper ridge over the western U.S. will continue to cause a dangerous and likely record-setting heat wave in much of the West into next week. Hot and humid conditions will also continue for much of the southern states and extending to the East Coast. ...Guidance/Predictability Assessment... Early in the medium range period, model guidance is fairly agreeable with the synoptic pattern, so the main concern is Beryl's track. 12/18Z operational models generally showed Beryl's center moving inland just south of Texas into far northern Mexico early Monday. However, AI/machine learning (ML) models have been denoting a landfall point a bit north into South Texas. Now the later- arriving 00Z ECMWF and especially the 00Z GFS show a northward trend compared to the previous model cycle. Then 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. Now that the 00Z ECMWF has come in with more recurvature, the latter is looking less likely. The variety in Beryl's track creates plenty of variability in the QPF footprint as well. See NHC for the official track forecasts for Beryl. Farther north, models are agreeable with the pattern of an upper high atop California shifting gradually east into the Central Great Basin/Four Corners with time, while the troughing across the central U.S. early week lifts north while moving eastward as the week progresses. The most uncertain aspect of the northern stream is when/how shortwaves move into British Columbia mid- to late week, affecting the pattern in the northwestern U.S. and northern tier. Details for those systems will have to be refined in future cycles. The WPC forecast used a multi-model blend favoring the 18Z GFS and 12Z ECMWF and CMC early in the period. Included the GEFS and EC means in the blend from Day 5 onward, ramping up the ensemble means' percentage to half by Day 6 and more Day 7 as model spread increased. ...Weather/Hazards Highlights... Beryl is likely to produce several inches of rainfall in South Texas during the first half of next week. As such, Slight Risks are in place in the Day 4-5 EROs for Monday and Tuesday. Monday's Slight Risk is considered a higher-end Slight where Beryl tracks. On Tuesday, there is more model spread and thus lower confidence in how Beryl may interact with an approaching frontal boundary farther north into central/east-central Texas, but potential exists for organized convection capable of producing heavy rainfall. The broad Slight Risk delineated for now on Day 5 may be able to be refined with time. There is certainly potential for upgrades to Moderate Risks in future updates if placement of higher totals comes into better agreement. This front and moisture could linger into midweek. Scattered thunderstorms are likely across the Gulf Coast states through much of next week given a moist and unstable airmass in place. Farther north, the upper trough pushing one or more cold fronts through the north-central to northeastern U.S. also will lead to some storms, with the bulk of the activity moving east with time from the Midwest/Great Lakes Monday toward the eastern U.S. Tuesday-Thursday. Some focus of the convective rain and sufficient instability for heavy rain rates in much of New York and Pennsylvania have prompted a Marginal Risk in the ERO for Day 5/Tuesday. Meanwhile, by Tuesday and beyond, some moisture may feed into the Four Corners states in a monsoonal pattern, and have a Marginal Risk in place for Day 5/Tuesday mainly for New Mexico, especially considering sensitivities due to burn scars and areas that have seen ample rainfall recently. The West will continue to see a major to extreme and long-lived heat wave into next week. Highs exceeding 110F should be widespread in the Desert Southwest, with typically hotter locations exceeding 120F. Farther north, highs into the 100s are forecast into Oregon and Washington and east into the Intermountain West, as temperatures soar 10-20F above normal with locally higher anomalies. Numerous daily records are likely to be broken during this heat wave, with monthly records not out of the question. The prolonged nature of the heat wave and record warm overnight temperatures will increase heat stress. Meanwhile, warmer than average temperatures in the Northeast early in the week should moderate by midweek. The Southeast should see near normal heat for this time of year--which is still hot and humid. The south-central U.S. should see some minor heat relief with below average temperatures given the clouds and rain chances. Tate 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